So far I have watched at least a dozen different videos about a PO300 misfire code on a later model Chevy Silverado and I saw a dozen different problems that have caused it. The 5.3 in my 05 Sierra is now in the metal bin and a 307 from a 1972 Chevelle, with a set of 202 heads and a camshaft from a mercruiser marine engine is sitting in its place hooked up to a 700R4 transmission. No more misfire code !!!
What a great idea... the IR detector. I have one and will be trying it on my own misfire problem. I can add that you can get those things for something like $15. I use mine for cooking. You can also check for heat leaks from your house--- if you find a portion of an exterior wall or of a ceiling below the attic, the inside of which is colder than other wall or ceiling panels, then maybe it needs better insulation.
@@moc5541 they have come down so far on pricing. There was a time when our fire department bought one $25,000 and it was a lower optioned unit. What a difference 25 years will make. Great multiple uses good suggestions. Thanks for watching
@@fastdadgarage-northsouthch4418 Well, I knew I needed a new cat when I heard it tapping and just got done putting the new one in and no more p0300 code. Thank god.
Pretty crazy the ecu isn't smart enough to determine which cylinder is misfiring, especially with injectors that clogged. The cars I usually work on can narrow it down to individual cylinders pretty accurately. P0300 should only code if they are all misfiring, but apparently chevrolet believes any number of cylinders counts as "random" 😅
I also did a compression test and it wasn’t the best. This is my friends truck he had another mechanic work on it, that guy tried several things($$$$) and then told the owner to tow it to a GM garage. Since installing the new injectors it was running good BUT the fuel pump is now losing pressure and sounds terrible.
So I did just like how you did with The digital thermometer. My truck was all running for about a minute or 2 and the exhaust manipuled. To get app to like 770°, and then got up to a 1000° But yes, having the same problem. So I'm pretty sure that is a sign of my Cadillac converters are clogged.
12 volts will open them up & a little tape around your straw will make it tight enough to see a spray pattern. You can back flush them also using this method. Be careful of sparks and flammables!
Making a wiring pig tail might make it safer, you can probably cut off a plug at the junk yard. I imagine holding it open for an extended amount of time might be hard on them as well.
My truck was running GREAT and had to replace cats due to constant code, i replaced cats and manifolds, new plugs and wires, now everything back together and now throwing p0300! Runs like shit 😢
I've used Seafoam for many years, and it seems to be paying off because my 2001 Silverado is i still going strong with over 200,000 miles. (Knock-on-wood !)
@@fastdadgarage-northsouthch4418 I've had good results cleaning injectors by blasting carb cleaner backwards through them. The spray bottle isnt enough to open them, but I clamped a piece of rubber hose to the injector nozzle, filled the hose with carb cleaner and then used my compressor to put about 60 psi and blast it through. Cleap way to back flush them. Also, those screens can often be replaced cheap.
Diagnostic trouble code (DTC) P0443 stands for Evaporative Emission System Purge Control Valve “A” Circuit. The code indicates that the PCM perceives a problem with the EVAP system purge valve or it’s control circuit 👍🏽
I have a p0300. changed spark plugs coils and cables. Coils seem to have fixed it but they are my other trucks coils the ones the truck has on seem to work they have spark etc not sure what the problem is
With that much crap in the injector, you have something in the fuel tank that is messed up. There is a filter screen on the pickup tube, and then the fuel filter. That stuff should never get to the injector. Just saying.
I have a 2004 Chevy Silverado 4.8l . I've got the same issues except my fuel pressure regulator is located in the fuel pump in the gas tank. I'm on disability and need to do it myself so I think I'm just gonna try cutting an access hole in my truck bed so I can pull the fuel pump straight out and get to the fuel pressure regulator. It's cheaper than paying a mechanic to drop the fuel tank, and it seems much easier than removing the truck bed. I dont have anyone to help me. I was wanting to do it as neatly as possible and put a hinge on it so I can open and close it. Looks aside, is this a good option for someone like me?
If memory serves it should be normally closed, it is a pressure reducer and should only open when pressure gets to high. Again if my memory is correct.
Thank you for the video. Im chasing a P0300 on my 07 Silverado 1500. Im trying the infrared “heat gun” on the exhaust manifold like you demonstrated. I notice a couple are showing 150f while the other 6 are in the 240f area. Is it safe to say the lower number i saw is where i should start?
My 2003 gmc 2500 6.0 is giving me a code of p0300 on the driver side of the motor at the very back when I unplug the coil the idle don't change but when I pull the rest of the coils one at a time the idle changes I got different wires swapped out different spark plugs and clean them can I even swap coil packs in different spots idk what to do at this point
I have a 1999 5.3 silverado. Same code and cant get it diagnosed. Really bad miss. Multiple misfires. Could it be coil packs? Ive changed plugs and wires. Unless is used the wrong gauge wires but i dont know enough about it.
I have a 2010 Silverado same p0300 code, I changed out the wires, plugs and cleaned the injectors. The vehicle cranks but it won’t fully start any tips? It’s getting fuel and spark but doesn’t have enough to turn over
Hello thanks for watching. I would check the fuel pressure(could be fuel pump). If it’s to low it wont start. You could also check the little fuel regulator, if it’s not operating correctly it will affect your fuel pressure also.
I have p0300 code, new spark plugs and wires and 2 new coils, 1 new O2 sensor 240k miles 2000 Silverado 5.3 starts great like it’s completely normal and once it warms up starts random misfiring, down on power as well as I tow every day, any ideas? It had a 02 sensor code before I changed it then everything went off ran perfect for about a day then p0300 code came back.
Have a 2001 Chevy Silverado...rough start and idle in the mornings and when cold. Changed spark plugs and wires... alternator..fuel pump and filter..air filter..and the coil packs..put on the CPU again and po300 still pops up and bank 1 sensor 1 code. Changed that 02sensor as well...still the same problem..felt like the engine was going to jump out today...but after about 20 minutes she levels off. Have no power issues while driving and acceleration. I don't know what else to do...only thing I didn't do was change injectors. When I got the feedback from the parts store it said to clean the injectors. Been using cleaners etc..please help
Have you been using injector cleaner you pour into the tank? I’ve never had good success with most of those products. You have done a lot of work! I would pull an injector or two, it’s not extremely difficult and then you could see if they are plugged.
@@fastdadgarage-northsouthch4418 yes Sir...been using the Lucas cleaner. I think I'm going to replace the IAC valve... if that doesn't solve it then I'll pull the rail and do the injectors
@@fastdadgarage-northsouthch4418 thank you for you're reply and thank you for the caption I lost my hearing from a job i use to have again thank you and you have a very good day :-)
I have a 02 chevy silverado 5.3 vortec with the p0300 code light on and I don't know what could it be I have had the spark plug wires and spark plugs replaced 6 months ago so I would doubt that's the issue any help would be greatly appreciated.
Work thru each system. Remember you need spark, fuel and air for ignition. Try to identify which cylinder is miss firing and then trouble shot each system.
@@fastdadgarage-northsouthch4418 I have not so I shall do that next! Do you think the tune could be adding to this issue? Or is that completely irrelevant?
I got an 04 2500 6.0 with 190,000 on her. I keep getting random misfires but more so when I hit high speeds around 70 mph. It recently got new plugs and wires at 170,000, new intake gasket along with knock sensors. With that many miles I'm leaning toward the injectors being clogged, a bad ignition coil, or possibly getting bad fuel pressure when it starts flashing at high speeds. Any input would be great
I’m having similar issues more so under load 2k-3200rpm it sounds restricted or something air filters clean maf is new had to replace the pigtails to the maf and just did plugs and wires about to do coils fuel filter upgraded injectors and pump
I've heard a crank position sensor relearn could solve the misfire at high speed. Look into it on other channels. I'm sure by now you've figured it out but maybe this will help someone else down the road.
Same problem with mine. Had a buddy hook up a real deal scanner and saw irregular voltage around your rpm range in the coils but under 2 it’ll never show. Had 4 random coils bad. Find someone that can do the same thing because oem coils aren’t cheap. Hope this helps you
The idea with checking temp is it gives you a quick reference of what cylinder may not be firing. If it was a plug I’d remove plug/ground and have someone turn it over and see if you have spark, be very careful doing this as you can get a jolt if you touch it while cranking.
If the transmission was installed correctly i don’t see how it could cause a misfire. damage to O2 sensor or exhaust could have occurred during installation, which possibly could be a problem. But that should be easy to see
Quick question . 02 silverado 5.3 with 223,000 miles. I keep getting a p0303 code. Never happens under load or while driving.. only occurs at idle. I have replaced plugs, wires and coil. What do you think could be the cause? Injector?
It’s so hard to say without having it in front of me. Sounds like spark side is good. Next would be fuel, check everything, pressure from fuel pump, regulator and then injectors.
I have a P0300 popping up on my 2004 Chevy Tahoe it has a 5.3 I change the spark plug spark plug wires and put new fuel injectors in it still has the same problem it also pops up air flow mass sensor but I replaced that and it still says air flow mass sensor. The truck runs rough have to keep my foot on the gas pedal so it can keep running. Any ideas on what I need to do?
Never thought to look at an injector that way. Thank you gonna try with my laser thermometer
I hope it helps, let me know. Thanks for commenting
So far I have watched at least a dozen different videos about a PO300 misfire code on a later model Chevy Silverado and I saw a dozen different problems that have caused it. The 5.3 in my 05 Sierra is now in the metal bin and a 307 from a 1972 Chevelle, with a set of 202 heads and a camshaft from a mercruiser marine engine is sitting in its place hooked up to a 700R4 transmission. No more misfire code !!!
@@arthurgay5746 that’s awesome…
What a great idea... the IR detector. I have one and will be trying it on my own misfire problem. I can add that you can get those things for something like $15. I use mine for cooking. You can also check for heat leaks from your house--- if you find a portion of an exterior wall or of a ceiling below the attic, the inside of which is colder than other wall or ceiling panels, then maybe it needs better insulation.
@@moc5541 they have come down so far on pricing. There was a time when our fire department bought one $25,000 and it was a lower optioned unit. What a difference 25 years will make. Great multiple uses good suggestions. Thanks for watching
Dude you may be a life saver. I totally spaced the catalytic converter being a problem.
It’s such a generic code, some many things possibly could be wrong.
@@fastdadgarage-northsouthch4418 Well, I knew I needed a new cat when I heard it tapping and just got done putting the new one in and no more p0300 code. Thank god.
Awesome video my man totally forgot to check manifold temp. we use to spray water on the manifold.
I never thought to use water, handy trick for when I don’t have a temp gun. Thanks
Pretty crazy the ecu isn't smart enough to determine which cylinder is misfiring, especially with injectors that clogged. The cars I usually work on can narrow it down to individual cylinders pretty accurately. P0300 should only code if they are all misfiring, but apparently chevrolet believes any number of cylinders counts as "random" 😅
Thanks for the video hope that's what's up with my 2004 5.3
Let me know what you find.
Straight to the point. Thank you very much.
Make sure the PCV system is functioning correctly. These engines are noted for Ring issues.
I also did a compression test and it wasn’t the best. This is my friends truck he had another mechanic work on it, that guy tried several things($$$$) and then told the owner to tow it to a GM garage. Since installing the new injectors it was running good BUT the fuel pump is now losing pressure and sounds terrible.
These engines are also known to go over 300k miles...
Good process , but I've learned to avoid crap Chinese aftermarket parts whenever possible. They seem to get worse every year.
I hope this helps someone. Sorry I called the Temperature Gun a heat gun, hope that wasn’t confusing. How do you start your diagnosis?
So I did just like how you did with The digital thermometer. My truck was all running for about a minute or 2 and the exhaust manipuled. To get app to like 770°, and then got up to a 1000° But yes, having the same problem. So I'm pretty sure that is a sign of my Cadillac converters are clogged.
Can you put a test pipe in place of the cat?
12 volts will open them up & a little tape around your straw will make it tight enough to see a spray pattern. You can back flush them also using this method. Be careful of sparks and flammables!
Making a wiring pig tail might make it safer, you can probably cut off a plug at the junk yard. I imagine holding it open for an extended amount of time might be hard on them as well.
I believe they run at a lower voltage, maybe around 5vdc.
That goo looks like excessive fuel stabilizer. If you use that make sure you mix per manufacturer instructions.
The current owner says he has not used any fuel additives. But he’s only owned it about 1.5 years can’t say what was used before that.
Great video! Thanks, tons of info in a short time!🌈
Hope it helped
The build up in the injector is a wax like film the gas leaves after sitting in the cold to long I think
Wow that was a lot of gunk! Way to track it down 👍
Mine just started doing this once it started getting cold . Once I need a smog of course
Thing is it runs perfect once it reaches temp
It does need cats replaced though 😢
@@kevinbennett2565 it’s tough when you have to get smog testing.
Thanks ! That is a clever way of diagnosing the P0300.
Thanks for watching, hoped it helped
My truck was running GREAT and had to replace cats due to constant code, i replaced cats and manifolds, new plugs and wires, now everything back together and now throwing p0300! Runs like shit 😢
@@mtnbkr265 that’s a bummer… wow
@@fastdadgarage-northsouthch4418 it ended up being a cracked spark plug, must have hit it by accident when installing the new manifold. Runs great now
@@mtnbkr265 that’s great. Glad you found it
Great video thanks for sharing 👍👍
Seafoam to clean injectors? Also fuel air spark and timing in a box
Sea foam is about the only additive I use, thanks for watching. Do you have good success using the ones you mention?
I've used Seafoam for many years, and it seems to be paying off because my 2001 Silverado is i still going strong with over 200,000 miles. (Knock-on-wood !)
Did you have issues with it going in to reduced engine power by any chance
Yes when I picked up the truck it would barely drive on the trailer
The injectors you linked are very cheap chinesium knockoffs. Better have a balance test done on them prior to installing.
Yes, this was a cheap “get the truck back on the road” solution.
@@fastdadgarage-northsouthch4418 I've had good results cleaning injectors by blasting carb cleaner backwards through them. The spray bottle isnt enough to open them, but I clamped a piece of rubber hose to the injector nozzle, filled the hose with carb cleaner and then used my compressor to put about 60 psi and blast it through. Cleap way to back flush them. Also, those screens can often be replaced cheap.
@@LSDale 12 volts will open them up & a little tape around your straw will make it tight enough to see a spray pattern.
Chinesium. Killing me. 😂
Would a bad purge valve thrw a misfire code aswell with the evap code cause that’s my problem right now
Not sure if it would throw same code. Sorry
Diagnostic trouble code (DTC) P0443 stands for Evaporative Emission System Purge Control Valve “A” Circuit. The code indicates that the PCM perceives a problem with the EVAP system purge valve or it’s control circuit 👍🏽
Mine says"p0300 misfire#3 cylinder, replaced the plug,wire and coil, and it still says misfire, so it's got to be the injector.
I can’t guarantee it, but it seems like you’ve worked through the options
i did injector on the codeing cylinder, also coils, plug, wires look good, intake manifold gasket, map sensor, still cranks wont start
Mine was driving me nuts with the po300 haunting, it was leaking intake gaskets
@@roltyd22 i got down to no codes, with a CEL, checked fluids, then ordered a new vortec. 5.3l Milkshake
You didn’t cycle the injector when you shot brake cleaner it that’s why It didn’t clean
Yup that is the correct way to do it.
I didnt have a 5 volt power supply to cycle them and if you use 12 volts it could burn up the coil inside.
I have a p0300. changed spark plugs coils and cables. Coils seem to have fixed it but they are my other trucks coils the ones the truck has on seem to work they have spark etc not sure what the problem is
You could try to replace with the originals one at a time and see if your problem returns.
With that much crap in the injector, you have something in the fuel tank that is messed up. There is a filter screen on the pickup tube, and then the fuel filter. That stuff should never get to the injector. Just saying.
That’s a good point, eventually I did change the fuel pump
I have a 2004 Chevy Silverado 4.8l . I've got the same issues except my fuel pressure regulator is located in the fuel pump in the gas tank. I'm on disability and need to do it myself so I think I'm just gonna try cutting an access hole in my truck bed so I can pull the fuel pump straight out and get to the fuel pressure regulator. It's cheaper than paying a mechanic to drop the fuel tank, and it seems much easier than removing the truck bed. I dont have anyone to help me. I was wanting to do it as neatly as possible and put a hinge on it so I can open and close it. Looks aside, is this a good option for someone like me?
Yes this can be a great option. Make sure you cut the hole large enough to work in. If you cut it to small you may have to do a second cut
@@fastdadgarage-northsouthch4418 Thank you
@Dave Roberts Thanks
On passenger side of fuel rail, the small black bleeder valve, is that suppose to be fully closed, slightly open, or completely open?
Thanks.
If memory serves it should be normally closed, it is a pressure reducer and should only open when pressure gets to high. Again if my memory is correct.
Thank you for the video. Im chasing a P0300 on my 07 Silverado 1500. Im trying the infrared “heat gun” on the exhaust manifold like you demonstrated. I notice a couple are showing 150f while the other 6 are in the 240f area. Is it safe to say the lower number i saw is where i should start?
That would be the direction I would go. Check the plug next see what they look like
I’ve seen the same material in a carburetor that’s been sitting about 3 months with fuel stabilizer added
Fuel additives can be nasty!
My 2003 gmc 2500 6.0 is giving me a code of p0300 on the driver side of the motor at the very back when I unplug the coil the idle don't change but when I pull the rest of the coils one at a time the idle changes I got different wires swapped out different spark plugs and clean them can I even swap coil packs in different spots idk what to do at this point
@@sonyagirl51 if you have coil packs, I would swap the coils around and see if the misfire follows the coil.
I have a 1999 5.3 silverado. Same code and cant get it diagnosed. Really bad miss. Multiple misfires. Could it be coil packs? Ive changed plugs and wires. Unless is used the wrong gauge wires but i dont know enough about it.
I hope you can help me and see this
Yes a coil pack could give you a misfire. You could move the coil you think it is and see if the misfire follows it.
I would move from one side of motor to the other so it’s obvious.
I have a 2010 Silverado same p0300 code, I changed out the wires, plugs and cleaned the injectors. The vehicle cranks but it won’t fully start any tips? It’s getting fuel and spark but doesn’t have enough to turn over
Hello thanks for watching. I would check the fuel pressure(could be fuel pump). If it’s to low it wont start. You could also check the little fuel regulator, if it’s not operating correctly it will affect your fuel pressure also.
I have p0300 code, new spark plugs and wires and 2 new coils, 1 new O2 sensor 240k miles 2000 Silverado 5.3 starts great like it’s completely normal and once it warms up starts random misfiring, down on power as well as I tow every day, any ideas? It had a 02 sensor code before I changed it then everything went off ran perfect for about a day then p0300 code came back.
Have you checked your fuel pressure?
@@fastdadgarage-northsouthch4418 not yet, I did replace all of the fuel system except for the lines about 2 years ago
@@chefvanzandt6375 some of the new fuel pumps don’t last very long. If you have a gauge to check it out it would be good.
@@fastdadgarage-northsouthch4418 ok I will thank you!
Have a 2001 Chevy Silverado...rough start and idle in the mornings and when cold. Changed spark plugs and wires... alternator..fuel pump and filter..air filter..and the coil packs..put on the CPU again and po300 still pops up and bank 1 sensor 1 code. Changed that 02sensor as well...still the same problem..felt like the engine was going to jump out today...but after about 20 minutes she levels off. Have no power issues while driving and acceleration. I don't know what else to do...only thing I didn't do was change injectors. When I got the feedback from the parts store it said to clean the injectors. Been using cleaners etc..please help
Have you been using injector cleaner you pour into the tank? I’ve never had good success with most of those products. You have done a lot of work! I would pull an injector or two, it’s not extremely difficult and then you could see if they are plugged.
@@fastdadgarage-northsouthch4418 yes Sir...been using the Lucas cleaner. I think I'm going to replace the IAC valve... if that doesn't solve it then I'll pull the rail and do the injectors
@@maradosmalls7590 sorry can’t be more helpful. There are some videos on how to clean dirty injectors once removed. I haven’t tried but worth a look
Marado did you get the issue resolved thank you
Sure haven't. Even changed the IAC valve... Now about to change the EGR valve and see what it does. After that I don't know what else to do!!!!
What we’re all the problems you were having with it having the code and stuff?
Did you have a lot of white smoke like excessive smoke coming from exhaust?
Yes I had some smoke but also it would barely stay running.
Hi fast Dad caption please and let me know when you have the caption working and I will come back to watch thank you :-)
They should be working. Enjoy the video hope it’s helpful
@@fastdadgarage-northsouthch4418 thank you for you're reply and thank you for the caption I lost my hearing from a job i use to have again thank you and you have a very good day :-)
Nicely explained!
Thanks
Wait wha the cost of them are low there over $100 bucks a peice and you have 8.
@@gamefadayz4121 I bought a complete set online, they weren’t that much. Under $100, checkout Amazon
I have a 02 chevy silverado 5.3 vortec with the p0300 code light on and I don't know what could it be I have had the spark plug wires and spark plugs replaced 6 months ago so I would doubt that's the issue any help would be greatly appreciated.
Work thru each system. Remember you need spark, fuel and air for ignition. Try to identify which cylinder is miss firing and then trouble shot each system.
@@fastdadgarage-northsouthch4418 oh ok thank you
I have an 04 Sierra with Longtube headers and a tune, I have a P0300 code, replaced my plugs but still have the code, any ideas what it could be?
Have you checked fuel pressure? Next you could see if all the coil packs are firing?
@@fastdadgarage-northsouthch4418 I have not so I shall do that next!
Do you think the tune could be adding to this issue? Or is that completely irrelevant?
@@J-Dawg99 can you easily remove the tune? Add it back after it’s running correctly
Crank sensor relearn and o2 sensors dealing wit this shit now also sMh
I got an 04 2500 6.0 with 190,000 on her. I keep getting random misfires but more so when I hit high speeds around 70 mph. It recently got new plugs and wires at 170,000, new intake gasket along with knock sensors. With that many miles I'm leaning toward the injectors being clogged, a bad ignition coil, or possibly getting bad fuel pressure when it starts flashing at high speeds. Any input would be great
Get a fuel pressure gauge, hook it up and take it for a drive. You’ll be able to see if your loosing pressure.
I’m having similar issues more so under load 2k-3200rpm it sounds restricted or something air filters clean maf is new had to replace the pigtails to the maf and just did plugs and wires about to do coils fuel filter upgraded injectors and pump
I've heard a crank position sensor relearn could solve the misfire at high speed. Look into it on other channels. I'm sure by now you've figured it out but maybe this will help someone else down the road.
Same problem with mine. Had a buddy hook up a real deal scanner and saw irregular voltage around your rpm range in the coils but under 2 it’ll never show. Had 4 random coils bad. Find someone that can do the same thing because oem coils aren’t cheap. Hope this helps you
Bit he's glowing
What about finding misfire on one of your plugs??
The idea with checking temp is it gives you a quick reference of what cylinder may not be firing. If it was a plug I’d remove plug/ground and have someone turn it over and see if you have spark, be very careful doing this as you can get a jolt if you touch it while cranking.
Can this happen after a transmission is replaced ?
If the transmission was installed correctly i don’t see how it could cause a misfire. damage to O2 sensor or exhaust could have occurred during installation, which possibly could be a problem. But that should be easy to see
Might need a crank shaft re learn, that will cause a miss fire
Quick question . 02 silverado 5.3 with 223,000 miles. I keep getting a p0303 code. Never happens under load or while driving.. only occurs at idle. I have replaced plugs, wires and coil. What do you think could be the cause? Injector?
It’s so hard to say without having it in front of me. Sounds like spark side is good. Next would be fuel, check everything, pressure from fuel pump, regulator and then injectors.
Now I’m gonna do this but I called the shop and he said that the valves can get sticker sometimes and cause a misfires or something similar to that
I have heard these engine have some valve problems. You could try a compression test, that may give you some info on valve train
I have a P0300 popping up on my 2004 Chevy Tahoe it has a 5.3 I change the spark plug spark plug wires and put new fuel injectors in it still has the same problem it also pops up air flow mass sensor but I replaced that and it still says air flow mass sensor. The truck runs rough have to keep my foot on the gas pedal so it can keep running. Any ideas on what I need to do?
Have you checked your fuel pressure?
Same thing happening to mine what did you do?
Whay did you guys come up with
@fastdadgarage-northsouthch4418 did you figure ypurs out
Hey guys just had this problem on my 2005 5.3 1500 pick up. Ended up being the upstream 02 sensors. ..
I had a p0300 was a coil.
Miss Fire can be from several different things. I think GM uses the po300 as a blanket warning.