I know this is an old video but it really helped me narrow down my issue. I have a misfire in the #2 cylinder in a 03 suburban 340k miles on it. I changed coils wires and plugs since I know these needed to be changed. Still a slight misfire but it runs much better. I unplugged bank 2 upstream and downstream o2 sensors. It runs a little better. I will just replace all 4 sensors. Thank you for this video. I was ready to junk the Chevy and buy a new one.
I see there is some TSB's for low fuel pressure causing a #2 misfire and some issues with G103 and wet 02 connectors dropping out banks but I guess until you get a bit more info it is hard to manufacture a hypothesis at this point. Look forward to some more data!
Seen the same TSB and definitely need more data like spark plug reading with intermittently long spark line @3 ms, no termination oscillations but that may be the inductive pickup & low kV at start of burn line...like the Pico better. I'm old school plug reader plus sounds like people already had their hands all over this one so who knows what he'll find...it's just starting to get good!
Thanks for the input, Eric! Have not seen that TSB....I should look at more TSBs haha! We will get some more data in Part 2 ;) Now tell Keith to get over here and share his thoughts! I wonder if he has seen this problem before on the Island? He did mention something about turning on the headlights and causing more misfires...crazy stuff lol
Keith is a smart cookie b/c the same ground (G104) for the 2,4,6,8 coils is also for the headlights by Mitchell for 5.3 but then their ground distribution shows G102 for all the coils & BBB shows G102 for grd distro & engine diagrams so I know it is in capable hands to figure it out if needed. It only takes a second to test...looking forward to the outcome. I'd also test the secondary of the good coils and see what you get for a waveform plus it only takes a second to pull a plug on a 5.3 I know it'll be good and there is always an important nugget your holding :D This as a low mileage Avalanche so did it just come out of storage or just driven low miles. Part II should be good. Of course these are all inconclusive conclusions from insufficient data b/c I can still list a lot more possibilities. Good suspense Ivan :D
My next step? I would assume it would be the same as anyone's... find out why it is misfiring haha. What's missing, fuel, spark, compression, timing, ability to breath? I would monitor as much as I could at the same time on the cylinder that was acting up the most. I guess at this point in the video not enough data is gathered to make an assumption. What data would I collect... hmmm If I knew 100% for sure spark was good, power, grounds good at coils I would gather injector drop and injector current along with fuel pressure just because that can be done easy enough, if fuel and spark were perfect and being delivered at the correct time and all I would go in cylinder and see if there is a valve spring or valve issue in general, like I say at this point I could make a big old list hah. WE NEED MORE DATA IVAN!!
After considering a few options I’d probably still go with “ ignition related “. First clue : severe misfire with flashing check engine light on cold start up after heavy rain,that gets better once warm. The spark line seemed low. Second clue : lean code you haven’t talked about... I would still approach this in layman’s terms and just swap coil/plug with a “ known good “. Seems pretty straight forward... Thanks for the video! 👍
I had a chevy express had steady misfires on a few cylinders at 2k rpms, crankshaft relearn took care of it... A few years ago i had a truck that had a few worn camshaft lobes made no noise and cause a steady misfire at idle and went away while driving it... Ive seen broken valve springs but not do what this is doing. and i don't know if it has active fuel management but the cylinders the shut down are 1,4,6,7. I can't wait to see what you end up with. I love seeing different faults it makes it more interesting!
i was going to say hairline crack in coil pack but this runs 8 individual coils so there goes that,maybe do a coil check to see if any sign of cracks..back to basics plugs wire and earth resistance. this DIY can't wait for part 2 now Ivan.
I was told by a 20+ year GM Master Certified Tech that it's not uncommon for the Misfire counts to sometimes count up on cylinders that are actually working fine in a dead miss situation. Especially on the cylinder that fires just before and just after the dead cylinder. But it can be on any of the other cylinders. So keep in mind the firing order whenever doing a misfire diagnosis. It could be counting up wrong cylinders. He strongly suggested to me that in a misfire diagnosis, fix the dead miss FIRST, THEN go back and watch the misfire counters. Otherwise if you only get your data while the dead miss is still happening, it can really bite you in wasted time
Hey Ivan! Hope your doing well from Pittsburgh. Spring is never coming! Haha. Question.. 04 Liberty 3.7L, got a code while cold idle still open loop for a O2 bank 2/2 low voltage a couple of weeks ago. Cleared and hasn’t come back. I did notice my LTFT is +10 Lean on both banks and fluctuating properly around zero on both STFT. Would you be concerned. How much influence does the downstream O2 sensors have on the LTFT’s? O2 sensor 2/2 does read a lower voltage thank 1/2 once warmed up. Should I throw parts cannon and buy two downstreams? No codes atm. Slightly rough idle at open loop. Can’t locate and vacuum leaks
Ok I finally watch the video burn time looks good but where is the primary switch on can't see ignition coil charge or is it just the way you have the scope setup
The low coolant is my main clue. I would try a liquid co2 tester to check for a head gasket leak. If it shows nothing, I would go with the other viewers comment about a leaking fuel injector on number 4.
It's been interesting so far. I'm most familiar with GM than anything else but even that doesn't help much here. However, my 5.7 liter had an intake gasket leak and that allowed water to get into the cylinders which fouled the spark plugs. That's all I got Ivan. Looking forward to the next video.
Best guess, someone had some plug wires off and didn’t connect them fully? LS wires can be a pain to connect and have to hear two clicks before they are fully on
I have a 2002 Chevy avalanche that dies when you drive it why is that I change my spark plugs and the wires and the coils too but it keeps die on me just want to know what I can do
Good proposals. I'll add mine to the collection: Either low coil primary voltage OR low compression in cylinder #2 (based on ignition waveform). Sticking (dirty) hydraulic lifter on #2 intake valve, leading to a tight valve and air-fuex mix leaking back to intake during compression stroke. Misfire indication on #2 due low power / no power. Extra fuel vapor in the intake MF + normal amount of fuel injection cause too rich mix to #6. Poor output -> misfire indication. Overall AFR still right -> fuel trims ok on bank 2. Repair: Oil change, lifter cleaner addtive to oil.
A few days ago I looked at A 07 escalade with a 6.2 ..very similar situation. I found a small amount of coolant getting into cylinder #2. Coolant was a bit low. Ran terrible upon cold starts but ran ok when hot but I could see some misfires on the scan tool. So is say you may have a head gasket issue...or broken valve spring. Thanks for The vid.love these cliffhangers
There are a number of comments suggesting bad ground connections. This could be eliminated with a few jumper wires to a solid ground on the engine and/or battery. This is a tough problem.
Great vid!! I’m guessing small coolant leak in head gasket between #2 and #6, on a cold start it misses more because it’s trying to burn the coolant that’s been slowly leaking in the cylinders. Sets more misfires at idle because it has less pressure blowing it out the exhaust valve then when reving it, also computer has more time to calculate somethings wrong. Funny smell might be burnt coolant in exhaust stream, flashing engine light maybe because saturated cylinder but could have also been the coil connecter that was unplugged. I also kinda think the wave looks funny, possibly coolant affecting it. That’s my theory?
Well, secondary ignition waveform shows that the energy isn't dropping down after the burn time. It's slowly trailing off. It isn't being completely dissipated showing an issue with the coil. Since this isn't Staten Island, you could compare waveform to another coil or do the old swap routine to see if it follows.
Pine Hollow Auto Diagnostics The burn time is all over the place. So, hydrocarbons are not fully being burned. That lean code could point to some unmetered air. Perhaps a ScannerDanner style soda bottle water test for a vacuum leak? But! Fuel trims looked good so, fuel injector issue perhaps.
I know this is an old video but I have a 2003 suburban and it had multiple misfires and flashing engine light. Burned fuel like crazy and I was smelling gas at the tailpipe. It shook so bad that the exhaust pipe was banging and every time I started the engine I would hear popping in the exhaust pipe. Shop told me I needed new fuel injectors. I did not do that because I’m dumping fuel. I watched this video and did some testing. I ended up changing all four O2 sensors and mass air flow. After that I was able to find I had misfires in 1,3 and 4 cylinders. Changed coils and plugs and wires and the engines runs like new. I purchased the suburban used and the engine light was on. Now no lights are on. The power is there and gas mileage is great. The shop was ready to throw parts at it. I don’t know what diagnostic tools they had but they were wrong. I am still using the injectors that came on the vehicle. Thanks for sharing this video.
If I had to guess, since I own the same engine & know it's history, I'd say busted valve spring ... but that seems to happen on the '07 and up ones more than these years, in addition to bad camshafts and stuck AFM lifters. GM sure knows how to build engines after 100+ years! It seems they're regressing in that aspect ... Need more data either way - looking forward to Part II ! :)
O2 sensor bad cause one side no fuel? I have misfires on 2,4,6. I’ve already throw a long list of parts on it. Do I replace the O2 pigtail and sensor? It’s vg30e ‘93 pathfinder.
Ivan, i doubt the spark plugs would be excessively worn out at 67k. They are iridium and should be good for 100k and in reality a lot more than that. I have an 03 silverado and changed mine at 127k and they were still working fine. My best guess is intermittent coil drivers in the ecm? Corrosion on the ecm harness?
Pull de plug! It would reveal oil/carbon shorting. Wiring harness could be shorting the injectors open intermittently. Smell the exhaust for rich mixture.
Really it's acting like a vacuum leak on the right side but fuel trim data doesn't bare that out, sometimes the simple answer fits best, poor atomization of fuel at idle, possible fouled plug. we know the truck has low miles for it's age. A stuck EGR valve would affect both sides same for lack of service; air filter, plugs, this engine is not vvt so can't be a cam phaser, you can't hear a vacuum leak or at least don't suspect one, coil voltage ramp rules out bad ground or coil, so we're left with something on the right side. looking forward to part 2
There doesn't seem to be any coil oscillations left at the end of the waveform. There should be around 3 or 4 'rings' remaining to show a healthy coil.
Odd spark plugs fitted between cylinders, or it needs a new set of plugs in general, Cold start dead miss though not sure if weak plugs would cause that, more like coolant in cylinder in that case.
If it was something bank specific ( fuel/vacume leak )you would expect the fuel trims to be countering ,my guess is spark happening outside the cylinder
I keep hearing a squeaky/ poppy noise. Is that pesky belt making that? If not possibly a leaking exhaust manifold gasket specially on cold starts would cause similar circumstances.
If you do , PLEASE FILM IT. Don't forget to ask about the Salt Eliminator & Silicone the Door Rubbers. Apparently Krown makes their own silicone spray & has more silicone in it than most.
my shout is incorrect timing chain adjustment from factory, so slight, eg one toothe at cam, so that it doesn't effect performance until now in its life a very slight MAF or O2 miss reading causes it to miss fire on that bank.
seeing that you have a bi directional scanner id try a crankshaft variation relearn to see if it makes a difference. i seen bank 1 misfiring too. free and easy for you.
My next step would be swap 2 and 4 coils with 1 and 3 to see If misfire travels. If it stays the same check injector balance test for bad injectors of course check for proper fuel pressure key forward engine off then engine on then under load.
I would do an in-cylinder compression test using a pressure wave transducer, I want to rule out valve train problems. Misfire on Cylinder 6 maybe due to the firing order, the ecm perceives a misfire on 6 due to a misfire on cylinder 2.
also, if you have one bank with misfires, do a smoke test, check the Integrity of the intake manifold gasket. Because it seems to misfire at idle when manifolf vacuum is the highest
But then why did the fuel trims not show this? I was very surprised to see the fuel trims being so steady and close to zero...no difference between Bank 1 and 2...
I would spray spark plug wires down with water and have someone power brake it. The rain in the morning is a clue, have seen a lot of GM vehicles with failing wires some times it's the easiest things. Keith
no guessing, trying to reason it out and up to now there is to less data/evidence to make an educated guess though. Observation is that firing kv seems to be LOW (even on snap) and the firing time in occasions goes up to ~3 ms with the spark line pretty flat. But the spark seems to happens in the combustion chamber....
Just going on the secondary waveform you logged, is it just me or when car starts to shudder, does the voltage after the burn time increase, i.e. indicative of a lean condition causing misfire? If it happening on just that bank, perhaps it's an inlet manifold leak as engine warms up? Would expect to see O2 sensor reporting a lean condition too once warmed up (which I think you had a code for prior to clearing them). Keep up the awesome diagnoses!
Yeah that was a crazy case study! Wish Eric would have used a PicoScope instead of the Vantage Pro so we would have seen the electrical noise at the fuel tank psi sensor!
I would do a relative compression test, just for the sake of it. And then maybe switching the coils and looking if the problem follows? And your coil waveform looks a little strange, looks much different than what I've seen on Scannerdanner videos. I guess there might be some weirdness going on with the ignition.
I'd start with what was easiest for me first, 1-making sure 12v feed to inj & coils was good, 2- making sure the common ground was good, and 3 making sure the common connection for the low Reference was good. That being said I am not a mechanic, just a diy guy.
Well I don't have access to a "O scope" so I'm stuck with nothing but a DVM and a test light. I do have an AC current clamp but that is not much good for this purpose. Would most likely try to put a small load on the the power and grounds with the test light, maybe even with the truck running just to see if there is any flicker on the bulb. Not a very good test I realize but with limited tools your limited in what you can try. I would also try to visually inspect the splices and the body connections to ground. I might even connect the DVM in series with the Power and ground circuits to monitor current flow (my meter is good for 20 amps) and compare the right and left bank?? The fuse would be an easy place to break the circuit for 12v positive maybe not as easy for the ground circuit, but shouldn't be that bad. If I was suspicious of of power or grounds I may even run a fused jumper to bypass the original wiring to see if it corrected the problem A really good visual inspection and tug test as well. Phew, that's all I got...just glad it's not my truck :)
I think your DIY testing method are already more thorough than those of %95 of the professional techs in the field!! I would go with the test light as well :)
Uses oil pressure to deactivate cylinders via the lifters. AFM lifters are known to stick closed and cause a misfire. Your symptoms could be be related to this. Possible clogged ar sticky lifters?
Bad Spark plug wire, looks like its firing in the cyl. but at times firing outside the cyl. Maybe bad plug, but I say wire! Iv been fouled with gm misfire counter 1 time, butall other times they are spot on.
My guess would be a bad injector on #4 cylinder, its the only 1 not misfiring on bank 2 which means the O2 sensor making corrections that r good enugh for cylinder #4 hance y u dont see any FT faults
In order to win PHAD t shirt, I would say bad spark plug boot, poor ground connection. As being an owner of GM vehicles. I have approached this situation before. Commonly bad ground issue. As coils don't really break.
If it has low miles then it's probably been sitting forever. I was going to say seriously bad gas had messed up the injectors but weird it would only effect one bank
Pine Hollow Auto Diagnostics Ok 👍 I will give my best giving the info gathered so far. I may be wrong 😂 first I thought ok let's have a peek at everything in common for the even cylinders 2,4,6,8 a quick glance at a schematic revealed they all 4 share power and ground. However once you started monitoring we found 2&6 were mostly effected and you mentioned it "felt" more as a single cylinder misfire. That put my initial thoughts on the side. then I started thinking what dose 2&6 have in common? Hmm firing order! 18726543 Bam. 2 then 6 at that point my mind is convinced we have a issue with cylinder #2 effects showing on 6 however feel #6 is ok "logical assumptions" my next step would be visually check #2 coil and wire. my feeling is you might see something obvious with the coil or wire. the spark plug is a little less likely but must check as well depending on finding. we just don't know. However we must not forget what's in common. The rest honestly and everything to this point are assumptions on my part. Until I got my eyes on the said. Cylinder 2 final answer 😂😂😂 for now hahaha love your content Ivan
Yeah I know haha that was mean of me. However so far I have not seen a theory that would explain ALL of the observations in Part 1 ;) Some very good guesses though! I honestly would never have guessed the actual problem on this truck myself after watching Part 1 lol
Just a shot in the dark, its not an air leak on one bank i suppose.....or something associated with the bad bank side ignition system...like water in plug or intermittent LT connection....something like that.....wonder if you can check the switching on the coils (dwell angle),,,,Fred in Uk
Definitely seemed ignition related just on Bank 2...and it was worse just at idle! The truck would spin the tires and run smooth if loaded in gear surprisingly.
I know this is an old video but it really helped me narrow down my issue. I have a misfire in the #2 cylinder in a 03 suburban 340k miles on it. I changed coils wires and plugs since I know these needed to be changed. Still a slight misfire but it runs much better. I unplugged bank 2 upstream and downstream o2 sensors. It runs a little better. I will just replace all 4 sensors. Thank you for this video. I was ready to junk the Chevy and buy a new one.
I see there is some TSB's for low fuel pressure causing a #2 misfire and some issues with G103 and wet 02 connectors dropping out banks but I guess until you get a bit more info it is hard to manufacture a hypothesis at this point. Look forward to some more data!
Seen the same TSB and definitely need more data like spark plug reading with intermittently long spark line @3 ms, no termination oscillations but that may be the inductive pickup & low kV at start of burn line...like the Pico better. I'm old school plug reader plus sounds like people already had their hands all over this one so who knows what he'll find...it's just starting to get good!
Thanks for the input, Eric! Have not seen that TSB....I should look at more TSBs haha! We will get some more data in Part 2 ;)
Now tell Keith to get over here and share his thoughts! I wonder if he has seen this problem before on the Island? He did mention something about turning on the headlights and causing more misfires...crazy stuff lol
Eric, I am curious, what would be your next step in this diag? What other data would you collect?
Keith is a smart cookie b/c the same ground (G104) for the 2,4,6,8 coils is also for the headlights by Mitchell for 5.3 but then their ground distribution shows G102 for all the coils & BBB shows G102 for grd distro & engine diagrams so I know it is in capable hands to figure it out if needed. It only takes a second to test...looking forward to the outcome. I'd also test the secondary of the good coils and see what you get for a waveform plus it only takes a second to pull a plug on a 5.3 I know it'll be good and there is always an important nugget your holding :D This as a low mileage Avalanche so did it just come out of storage or just driven low miles. Part II should be good. Of course these are all inconclusive conclusions from insufficient data b/c I can still list a lot more possibilities. Good suspense Ivan :D
My next step? I would assume it would be the same as anyone's... find out why it is misfiring haha. What's missing, fuel, spark, compression, timing, ability to breath? I would monitor as much as I could at the same time on the cylinder that was acting up the most. I guess at this point in the video not enough data is gathered to make an assumption. What data would I collect... hmmm If I knew 100% for sure spark was good, power, grounds good at coils I would gather injector drop and injector current along with fuel pressure just because that can be done easy enough, if fuel and spark were perfect and being delivered at the correct time and all I would go in cylinder and see if there is a valve spring or valve issue in general, like I say at this point I could make a big old list hah. WE NEED MORE DATA IVAN!!
interesting case study as usual,waiting for part 2
great job ivan,
cheers.....
Another great video Ivan I won't spoil it for everybody we will wait till Part 2 great video
No worries Leon, did "car whisperer" Keith already tell you what's wrong with the truck? xD
Pine Hollow Auto Diagnostics hahah no I told him
I know as well 👀
bodgit and leggit garage yea right Leon you have these trucks over there?
Joe Shearer hahahah no never even heard of it before lol
After considering a few options I’d probably still go with “ ignition related “. First clue : severe misfire with flashing check engine light on cold start up after heavy rain,that gets better once warm. The spark line seemed low.
Second clue : lean code you haven’t talked about...
I would still approach this in layman’s terms and just swap coil/plug with a “ known good “. Seems pretty straight forward...
Thanks for the video! 👍
Yes! The lean code! Could be due to the misfires...but fuel trims looked perfect so far. Part 2 will get interesting :)
Pine Hollow Auto Diagnostics Did you look at fuel trims before or after resetting the CEL?
I had a chevy express had steady misfires on a few cylinders at 2k rpms, crankshaft relearn took care of it... A few years ago i had a truck that had a few worn camshaft lobes made no noise and cause a steady misfire at idle and went away while driving it... Ive seen broken valve springs but not do what this is doing. and i don't know if it has active fuel management but the cylinders the shut down are 1,4,6,7. I can't wait to see what you end up with. I love seeing different faults it makes it more interesting!
i was going to say hairline crack in coil pack but this runs 8 individual coils so there goes that,maybe do a coil check to see if any sign of cracks..back to basics plugs wire and earth resistance. this DIY can't wait for part 2 now Ivan.
I was told by a 20+ year GM Master Certified Tech that it's not uncommon for the Misfire counts to sometimes count up on cylinders that are actually working fine in a dead miss situation. Especially on the cylinder that fires just before and just after the dead cylinder. But it can be on any of the other cylinders. So keep in mind the firing order whenever doing a misfire diagnosis. It could be counting up wrong cylinders. He strongly suggested to me that in a misfire diagnosis, fix the dead miss FIRST, THEN go back and watch the misfire counters. Otherwise if you only get your data while the dead miss is still happening, it can really bite you in wasted time
Hey Ivan! Hope your doing well from Pittsburgh. Spring is never coming! Haha. Question.. 04 Liberty 3.7L, got a code while cold idle still open loop for a O2 bank 2/2 low voltage a couple of weeks ago. Cleared and hasn’t come back. I did notice my LTFT is +10 Lean on both banks and fluctuating properly around zero on both STFT. Would you be concerned. How much influence does the downstream O2 sensors have on the LTFT’s? O2 sensor 2/2 does read a lower voltage thank 1/2 once warmed up. Should I throw parts cannon and buy two downstreams? No codes atm. Slightly rough idle at open loop. Can’t locate and vacuum leaks
Ok I finally watch the video burn time looks good but where is the primary switch on can't see ignition coil charge or is it just the way you have the scope setup
The waveform looked kinda weird, but the spark was definitely occurring inside cylinder based on the burn line...
Pine Hollow Auto Diagnostics yes but what about the switch on ignition coil charge I did not see it in the waveform
Not sure...all I know is that coil definitely fired lol
Something in the harness. Wiggle test it. Can the coils be swap around. Bank 1 to bank 2
This is super interesting. Can't wait for next part.
The low coolant is my main clue. I would try a liquid co2 tester to check for a head gasket leak. If it shows nothing, I would go with the other viewers comment about a leaking fuel injector on number 4.
It's been interesting so far. I'm most familiar with GM than anything else but even that doesn't help much here. However, my 5.7 liter had an intake gasket leak and that allowed water to get into the cylinders which fouled the spark plugs. That's all I got Ivan. Looking forward to the next video.
Actually Wyatt, your guess is closer than most in the comments...you will see what I mean in Part 2 :)
in cylinder running bank to bank comparison use pico look for pressure rise difference excellet video Ivan thanks
The ignition advance seems all over the place. I wounder if this is a crank sensor problem?
Best guess, someone had some plug wires off and didn’t connect them fully? LS wires can be a pain to connect and have to hear two clicks before they are fully on
If it passes the water test I would check for intake gasket leak? Keith
Headed to part 2, no delayed suspense for me :-)
Good video Ivan going be waiting for number 2
I would have said head gasket or some sort of air leak but would a HG issue show up on a compression test?
Michael Manley yes
I have a 2002 Chevy avalanche that dies when you drive it why is that I change my spark plugs and the wires and the coils too but it keeps die on me just want to know what I can do
Good proposals. I'll add mine to the collection: Either low coil primary voltage OR low compression in cylinder #2 (based on ignition waveform). Sticking (dirty) hydraulic lifter on #2 intake valve, leading to a tight valve and air-fuex mix leaking back to intake during compression stroke. Misfire indication on #2 due low power / no power. Extra fuel vapor in the intake MF + normal amount of fuel injection cause too rich mix to #6. Poor output -> misfire indication. Overall AFR still right -> fuel trims ok on bank 2. Repair: Oil change, lifter cleaner addtive to oil.
Great thought process. I like that you explained how the fuel trims are still OK, even with the misfires :)
A few days ago I looked at A 07 escalade with a 6.2 ..very similar situation. I found a small amount of coolant getting into cylinder #2. Coolant was a bit low. Ran terrible upon cold starts but ran ok when hot but I could see some misfires on the scan tool. So is say you may have a head gasket issue...or broken valve spring. Thanks for The vid.love these cliffhangers
GM 6.2 are nighmares lol
Pine Hollow Auto Diagnostics amen to that!😭😭😭😭😭
3.x L lower intake gaskets
Pine Hollow Auto Diagnostics Ivan you cannot have a nightmare without any 'T' 😂
Michael O LMAO...he said it Mexican style so I could understand...😂😂😂😂😂😂
Have the whole passenger bank not firing with a o2 sensor on same side had a code, could this actually stop the whole bank from firing.
There are a number of comments suggesting bad ground connections. This could be eliminated with a few jumper wires to a solid ground on the engine and/or battery.
This is a tough problem.
Great vid!! I’m guessing small coolant leak in head gasket between #2 and #6, on a cold start it misses more because it’s trying to burn the coolant that’s been slowly leaking in the cylinders. Sets more misfires at idle because it has less pressure blowing it out the exhaust valve then when reving it, also computer has more time to calculate somethings wrong. Funny smell might be burnt coolant in exhaust stream, flashing engine light maybe because saturated cylinder but could have also been the coil connecter that was unplugged. I also kinda think the wave looks funny, possibly coolant affecting it. That’s my theory?
Not bad! I like your thought process! You did explain all the data presented :)
Cracked or leaking exhaust manifold before pre cat o2??? Although fuel trims looked ok?... looking forward to next video :)
Well, secondary ignition waveform shows that the energy isn't dropping down after the burn time. It's slowly trailing off. It isn't being completely dissipated showing an issue with the coil. Since this isn't Staten Island, you could compare waveform to another coil or do the old swap routine to see if it follows.
The waveform looked kind of weird. I should have checked a cylinder on the "good" bank!
If it wasn't the coil, then that weird waveform would seem to indicate that it's something internal to the combustion chamber.
Indeed...what is weird inside?
Pine Hollow Auto Diagnostics The burn time is all over the place. So, hydrocarbons are not fully being burned. That lean code could point to some unmetered air. Perhaps a ScannerDanner style soda bottle water test for a vacuum leak? But! Fuel trims looked good so, fuel injector issue perhaps.
Curious of the history as with so few miles in 13 yrs, does vehicle sit through winters while owner vacations in the south?
I know this is an old video but I have a 2003 suburban and it had multiple misfires and flashing engine light. Burned fuel like crazy and I was smelling gas at the tailpipe. It shook so bad that the exhaust pipe was banging and every time I started the engine I would hear popping in the exhaust pipe. Shop told me I needed new fuel injectors. I did not do that because I’m dumping fuel. I watched this video and did some testing. I ended up changing all four O2 sensors and mass air flow. After that I was able to find I had misfires in 1,3 and 4 cylinders. Changed coils and plugs and wires and the engines runs like new. I purchased the suburban used and the engine light was on. Now no lights are on. The power is there and gas mileage is great. The shop was ready to throw parts at it. I don’t know what diagnostic tools they had but they were wrong. I am still using the injectors that came on the vehicle. Thanks for sharing this video.
If I had to guess, since I own the same engine & know it's history, I'd say busted valve spring ... but that seems to happen on the '07 and up ones more than these years, in addition to bad camshafts and stuck AFM lifters. GM sure knows how to build engines after 100+ years! It seems they're regressing in that aspect ...
Need more data either way - looking forward to Part II ! :)
I have a 2007 1500 with Cylinder deactivation 5.3. Kinda does the same thing misses at idle but runs perfect.
Same, any luck?
O2 sensor bad cause one side no fuel? I have misfires on 2,4,6. I’ve already throw a long list of parts on it. Do I replace the O2 pigtail and sensor? It’s vg30e ‘93 pathfinder.
Yup replace the O2 sensor. Denso or NTK only :)
Ivan, i doubt the spark plugs would be excessively worn out at 67k. They are iridium and should be good for 100k and in reality a lot more than that. I have an 03 silverado and changed mine at 127k and they were still working fine. My best guess is intermittent coil drivers in the ecm? Corrosion on the ecm harness?
Good video Ivan. I can't wait for Part 2. I hope it won't be a Pay-per-View. lol :-)
LOL November is the last moth for paid videos! Thanks for the idea ;)
Has it had new plugs installed. If it has my call is not the factory correct plugs. These ls moters don’t like anything but dubble platinum plugs
Thanks bro this video helped me a lot and each time I learn more!!!
Pull de plug! It would reveal oil/carbon shorting. Wiring harness could be shorting the injectors open intermittently. Smell the exhaust for rich mixture.
Best guess so far, William. The exhaust did smell a bit funny to me. But why did fuel trims not go negative when this happened?
Really it's acting like a vacuum leak on the right side but fuel trim data doesn't bare that out, sometimes the simple answer fits best, poor atomization of fuel at idle, possible fouled plug. we know the truck has low miles for it's age. A stuck EGR valve would affect both sides same for lack of service; air filter, plugs, this engine is not vvt so can't be a cam phaser, you can't hear a vacuum leak or at least don't suspect one, coil voltage ramp rules out bad ground or coil, so we're left with something on the right side. looking forward to part 2
There doesn't seem to be any coil oscillations left at the end of the waveform. There should be around 3 or 4 'rings' remaining to show a healthy coil.
I always check firing order when seeing 2 cylinders misfiring. On these 5.3 2 and 6 fire 1 after the other
Odd spark plugs fitted between cylinders, or it needs a new set of plugs in general,
Cold start dead miss though not sure if weak plugs would cause that, more like coolant in cylinder in that case.
If it was something bank specific ( fuel/vacume leak )you would expect the fuel trims to be countering ,my guess is spark happening outside the cylinder
I keep hearing a squeaky/ poppy noise. Is that pesky belt making that? If not possibly a leaking exhaust manifold gasket specially on cold starts would cause similar circumstances.
yeah just a squeaky belt haha
A New York State Birdy Tells me that a certain Mr.Ivan might be going to Krown Town Soon ;) EXCELLENT CHOICE!
As soon as I get a bit of free time lol
If you do , PLEASE FILM IT. Don't forget to ask about the Salt Eliminator & Silicone the Door Rubbers. Apparently Krown makes their own silicone spray & has more silicone in it than most.
I'd swap the coils and plugs between 1 and 2 & see if the problem moves with it, But my gut says it's ground related.
Need to check fuel pressure regulator diaphragm rupture possible
I would like to know because I have a 5.3 that is doing the same thing except on 3 and 7.
Exselecte diagnostic amigo nice video
my shout is incorrect timing chain adjustment from factory, so slight, eg one toothe at cam, so that it doesn't effect performance until now in its life a very slight MAF or O2 miss reading causes it to miss fire on that bank.
seeing that you have a bi directional scanner id try a crankshaft variation relearn to see if it makes a difference. i seen bank 1 misfiring too. free and easy for you.
I also thought of doing this. However, the truck was physcally shaking during the constant misfires, so I believed the counters overall.
wiring harness being pulled by engine movement. maybe coil current ramp when dead misfire occurs
its the air intake manifold gaskets. i had the same problem with my 5.3l
Good possibly be a bad block ground to the negative side of the coil packs
Interesting thought! Is it a different ground for the two banks?
Pine Hollow Auto Diagnostics Yes
This was my thought as well
Worse in park than under load
This a good suggestion. It also COULD explain why the misfires improve under load as the engine twists slightly in the mounts.
My next step would be swap 2 and 4 coils with 1 and 3 to see If misfire travels. If it stays the same check injector balance test for bad injectors of course check for proper fuel pressure key forward engine off then engine on then under load.
I would do an in-cylinder compression test using a pressure wave transducer, I want to rule out valve train problems. Misfire on Cylinder 6 maybe due to the firing order, the ecm perceives a misfire on 6 due to a misfire on cylinder 2.
also, if you have one bank with misfires, do a smoke test, check the Integrity of the intake manifold gasket. Because it seems to misfire at idle when manifolf vacuum is the highest
stanghp1 the fuel trims were fine though. Dont u think a intake leak would show up in the trims
Good theory, and follow up question :)
Intake manifold leak on passenger side, driver side starting to show same issue.
would a vacuum leak show itself in the fuel trims? The long and short terms looked the same for both banks...
oh yeah it would
not necessarily in a maf engine (if this is one) it would only adjust to the air moving over the sensor
Those engines are notorious to have problems with the intake gaskets
Could it be the Plugs? Hope your cold leaves soon. Enjoy your video's.
It could absolutely be the plugs. By why so consistently only on one bank??
Throw some plugs and wires fix your ground and call it a fix 😁 let's see what's next Ivan...
Hey ivan it will appear to maybe a vacuum leak around the intake or something effecting that bank
But then why did the fuel trims not show this? I was very surprised to see the fuel trims being so steady and close to zero...no difference between Bank 1 and 2...
Thanks bro really helpful 👌 👍 💯
I would spray spark plug wires down with water and have someone power brake it. The rain in the morning is a clue, have seen a lot of GM vehicles with failing wires some times it's the easiest things. Keith
Great first step. It would be a big coincidence for all 4 coils/wires to start failing on one bank all at the same time however...
That is a good idea keith frisell !!
no guessing, trying to reason it out and up to now there is to less data/evidence to make an educated guess though.
Observation is that firing kv seems to be LOW (even on snap) and the firing time in occasions goes up to ~3 ms with the spark line pretty flat. But the spark seems to happens in the combustion chamber....
Excellent observations. What other data and evidence would you like to see? What would you do next?
A leaking head gasket that leaks more when cold then seals when it heat expands.
And probably the primary coil codes were triggered by someone unplugging the connectors
That was my first thought. Wanted to start from a clean slate!
Just going on the secondary waveform you logged, is it just me or when car starts to shudder, does the voltage after the burn time increase, i.e. indicative of a lean condition causing misfire? If it happening on just that bank, perhaps it's an inlet manifold leak as engine warms up? Would expect to see O2 sensor reporting a lean condition too once warmed up (which I think you had a code for prior to clearing them). Keep up the awesome diagnoses!
Great observations! That P0174 Bank 2 Lean turns out to be quite important ;)
Sounds to me like it needs a new windshield wash pump... ;)~
JK...I'm still stuck on that Eric O evap code which turned out to be faulty p/s sensor...
Yeah that was a crazy case study! Wish Eric would have used a PicoScope instead of the Vantage Pro so we would have seen the electrical noise at the fuel tank psi sensor!
I think it has a cracked spark plug that is showing up more when cold
My thoughts on this were with the majority.....some kind of earth fault...but then again... Could it be...mmm...think i'll await part 2
I would do a relative compression test, just for the sake of it. And then maybe switching the coils and looking if the problem follows? And your coil waveform looks a little strange, looks much different than what I've seen on Scannerdanner videos. I guess there might be some weirdness going on with the ignition.
possible causes ignition coil,air leak
Ivan, I'll mail u a dorman hat.....
I'm going to say coil. Didn't see coil oscillations. Maybe the other coils are failing
I'd start with what was easiest for me first, 1-making sure 12v feed to inj & coils was good, 2- making sure the common ground was good, and 3 making sure the common connection for the low Reference was good. That being said I am not a mechanic, just a diy guy.
That would be a great starting point! What tools would you use to perform those initial tests?
Well I don't have access to a "O scope" so I'm stuck with nothing but a DVM and a test light. I do have an AC current clamp but that is not much good for this purpose. Would most likely try to put a small load on the the power and grounds with the test light, maybe even with the truck running just to see if there is any flicker on the bulb. Not a very good test I realize but with limited tools your limited in what you can try. I would also try to visually inspect the splices and the body connections to ground. I might even connect the DVM in series with the Power and ground circuits to monitor current flow (my meter is good for 20 amps) and compare the right and left bank?? The fuse would be an easy place to break the circuit for 12v positive maybe not as easy for the ground circuit, but shouldn't be that bad. If I was suspicious of of power or grounds I may even run a fused jumper to bypass the original wiring to see if it corrected the problem A really good visual inspection and tug test as well. Phew, that's all I got...just glad it's not my truck :)
Oh and thanks for doing this, makes it interesting! Great videos, I've learned a lot from watching.
I think your DIY testing method are already more thorough than those of %95 of the professional techs in the field!! I would go with the test light as well :)
Hey that means a lot coming from a guy with your skills, thanks! Looking forward to Part 2!
Bet it's clogged or dirty injectors. Dripping at idle but under load fuel pressure overcomes dirty nozzle and added fuel stops miss
hmmm I guess it's possible. But with leaky injectors I would also expect Bank 2 fuel trims to go significantly negative, and maybe a Rich code?
dose it have active fuel management
what is active fuel management? No fancy systems on this one...
Uses oil pressure to deactivate cylinders via the lifters. AFM lifters are known to stick closed and cause a misfire. Your symptoms could be be related to this. Possible clogged ar sticky lifters?
So what’s the problem?
Nice one! But we needed to see another cyllinder waveform before the guess game )
Yes Vladimir, I should have checked a "good" cylinder on the opposite bank. Dang it haha
Guess we just wait and hope part 2 is going to be free ))
I hope secondary ignition waveforms on the se ond part 😁😁
Writing too soon 😂😂
Low kv probably as a lot of techs said bad ground so the coils can't build enough voltage...
Can't tell. It's either missing spark, fuel or compression. Pray it's not the last one, that one's the hardest to figure out.
What would you next if you were in the diagnostics hot seat?
Well you said the fuel trims look good. I'd look at ignition first then fuel then compression/exhaust.
Plug or injector?
Please explain your guess to support data shown in video :)
Bad Spark plug wire, looks like its firing in the cyl. but at times firing outside the cyl. Maybe bad plug, but I say wire!
Iv been fouled with gm misfire counter 1 time, butall other times they are spot on.
My guess would be a bad injector on #4 cylinder, its the only 1 not misfiring on bank 2 which means the O2 sensor making corrections that r good enugh for cylinder #4 hance y u dont see any FT faults
Interesting theory. What do you mean by "bad injector" like flowing too much or too little? Would you expect negative fuel trims then?
Are you a one person / man shop?
yup just me and Diagnostic Dog haha
Ivan is a Renaissance man....he doesn't need anyone else. I mean the man fixed an eye glass cutting machine!
Diagnosis was?
Because of the age and low mileage I would think of a corroded ground connection or wire that has a bad connection.
Restricted injector/Old plug. Is what on guessing
Just one?
Pine Hollow Auto Diagnostics I'm at work. Didn't give it my full attention lol
Random wild guess, it has 14 year old plugs and wires on it
Sounds as though half of the cylinders aren’t firing. I thought gm had vehicles that shut down 4 of 8 cylinders to save on fuel.
It read "9.8mpg AVG" on the display hahaha
James Nasto The only way GM ever saved on fuel was with a crank no start.
Gm did not start using that cylinder deactivation system until like 2007 or so. This Truck is a 2004
In order to win PHAD t shirt, I would say bad spark plug boot, poor ground connection. As being an owner of GM vehicles. I have approached this situation before. Commonly bad ground issue. As coils don't really break.
Josh, you won't be disappointed in Part 2 ;)
Bad maf?
I feel like it's the intake manifold gaskets.
Seriously though, what about intake manifold issues on that bank 2, maybe smoke test is in order?..Remember this is GM...
If it has low miles then it's probably been sitting forever. I was going to say seriously bad gas had messed up the injectors but weird it would only effect one bank
just like that Ford dump truck huh :D
Look at the plug wires.
I did...they looked OK.
Oh no no , I need an in cylinder and a injector drop test to be certain sir . Scope pattern to crappy
Injector drop test? Fair enough. Part 2 coming right up ;)
Actually the waveform showed a rich fouled spark plug or carbon tracking just didn't have the detail of a Pico. Definitely needed more info though
I'm sticking to my guns on this one Ivan 🍻 so far lol I will keep zipped for the time being
Please share your thoughts with the class, Will! You might even win a free PHAD t-shirt if you are correct ;)
I want a free t-shirt but there is one problem that means I have to watch the video😝😝😝😝😝😝
There are worse ways to waste your time on the internet hahaah
Pine Hollow Auto Diagnostics Ok 👍 I will give my best giving the info gathered so far. I may be wrong 😂
first I thought ok let's have a peek at everything in common for the even cylinders 2,4,6,8 a quick glance at a schematic revealed they all 4 share power and ground. However once you started monitoring we found 2&6 were mostly effected and you mentioned it "felt" more as a single cylinder misfire. That put my initial thoughts on the side. then I started thinking what dose 2&6 have in common? Hmm firing order! 18726543 Bam. 2 then 6 at that point my mind is convinced we have a issue with cylinder #2 effects showing on 6 however feel #6 is ok "logical assumptions" my next step would be visually check #2 coil and wire. my feeling is you might see something obvious with the coil or wire. the spark plug is a little less likely but must check as well depending on finding. we just don't know. However we must not forget what's in common. The rest honestly and everything to this point are assumptions on my part. Until I got my eyes on the said. Cylinder 2 final answer 😂😂😂 for now hahaha love your content Ivan
robinsonsauto that'd be even bank if it's 2, 4, 6 & 8?!
I'd only be guessing but I'm guessing a vacuum leak. Lean codes and misfires but you haven't given us much else to go on lol
Yeah I know haha that was mean of me. However so far I have not seen a theory that would explain ALL of the observations in Part 1 ;) Some very good guesses though!
I honestly would never have guessed the actual problem on this truck myself after watching Part 1 lol
Just a shot in the dark, its not an air leak on one bank i suppose.....or something associated with the bad bank side ignition system...like water in plug or intermittent LT connection....something like that.....wonder if you can check the switching on the coils (dwell angle),,,,Fred in Uk
Definitely seemed ignition related just on Bank 2...and it was worse just at idle! The truck would spin the tires and run smooth if loaded in gear surprisingly.
My guess is intake leak but need to see snap throttle ign test first.