Finding a faulty GDI Injector - Experiment
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- เผยแพร่เมื่อ 7 ก.พ. 2025
- I unlike a lot of technicians have access to some expensive specialty tools that the dealerships use to quickly find faulty Fuel Injectors so I wanted to try and prove a bad injector with tools easily available to techs in the aftermarket world.
Wow that O2 sensor responds fast on the scope! Very neat test! For these codes sometimes the color of the spark plugs can be a big clue/low tech confirmation method as well 👍
Jake, hold your head high, you are a smart man, excellent teacher, and you are on your way to being the next big automotive You Tube channel, Awesome, Awesome, Awesome channel
Brother I can see you’re on your way to being the next big channel on this TH-cam for sure! No substitute for hard work and you know that because you are successful in what you do before you got on TH-cam. I definitely enjoyed the video and I am working to be a better tech. You definitely taught me some new things in this video. I have a total of 30 years under hood experience. But I was not the diagnostic person. I’m working to change that for the last four years and we appreciate the hard work that you put in these videos! God bless you
I'm sure you and everyone else in the comments has seen this but my favorite way is using an injector pulse tester. Just hook up to the injectors one by one, hook up a pressure gauge and just watch pressure drop from each injector. I've had very good luck with this. Obviously these injectors require some disassembly to get to or you can just unplug the pcm and test them that way. Clearly a tad bit more invasive but my favorite way to check fuel flow. Unfortunately I was just on amazon and noticed the Otc tester has gone up a fair amount in the past few years. Picked mine up for $60 quite some time ago and even though its used seldomly, its paid itself over multiple times.
@@autodiagyt Ahh i see. Thats a great point. Thanks for the reply!
Nice to see that AFIT and the Balance test pointed to the same injector. In SI, GM will have you do some maths and use a 20 Percent rule with the pressure drops. You first GDS data when calculated showed the injector under 20 Percent!!!!!!!! But, it was still the culprit. Makes me wonder if the tolerance should be 10 to 15 Percent!!!💁. The O2 change was great evidence for the case. Nice Job!!!!
Thank you for sharing different ways of figuring out which injecting has different pressure than the rest...
This is an incredibly valuable video. This gives the aftermarket a competitive edge for injector diagnostic.
Good for you, to show various methods with different software. That's a trademark of the best teachers, Paul Danner comes to mind.
If you take the raw numbers from the aftermarket scanners and find the average then divide the average by each cylinder’s raw number it will show you how close to “1” each cylinder is. With Snapon, I get 1.11, .87, .96,.93,1.01 and 1.05. - - showing cylinders 1 and 2 both being more than 0.1 from mean. With the Autel, I get 1.12, .84, 1.02, 1.01, 1.03 and .99. - - again showing both cylinders 1 and 2 being more than 0.1 from mean. If you only had the aftermarket scanners you’d probably replace 1 and 2 injector. I find this very interesting. Thanks for doing these experiments and sharing your thoughts and methods.
P219b on a 2011 Silverado 4.3 liter. Might have been a lil older or newer don’t remember. Shop replaced injectors but didn’t fix it. It was random bank 1 trims would go way positive intermittently but only front o2 showed lean swapped o2 sensors from bank to bank no improvement. Turned out pcm intermittently quit supplying bias voltage to o2.
What we use on common rail diesels ; scope injector control (for sync/firingorder) vs fuel rail pressure (ac coupled), if your scope is sensitive enough you should be able too see a faulty injector (higher pressure drop)
Awesome video! Thanks for taking the time to compare different tools.
The thermostat can be replaced without removing the fuel rails. We take the coolant pipe loose on the drives side of the engine and transfer the new thermostat and o-ring to the old pipe.
You gonna be one of the best youtune channels that's for sure. Remember that your are becoming whoever inspired you to make videos and teach other technicians or wanna be techs (like me lol). Before u realize you will be the person others look up to. I've followed you for 3 weeks and I've seen and you have doubled ur number of subscribers. Once I get out of the Navy I want to fix cars for a living. Maybe go to school too. What would be your advise? I know u don't got time to reply everybody so maybe touch up on next videos. I like your new intros and logo btw. Still waiting on the punch line at the end though lol. Once again thank you for sharing your knowledge! Greetings from San Diego, CA
I've seen several cases of this happening after a t-stat replacement on this motor. One on a car I worked on. I was as careful as possible, but it came back a couple days later. Horrible design. I'm at the point where I'm selling injectors with the job. Honestly didn't notice that the injector was bent. Also- ran injector flow test several times, different results every time. My understanding of the GDI injectors is they should flow exactly the same. Even a one PSI diff is out of spec. Great info, I'll know going forward to look for the bend!!!
Nice breakdown
That was interesting making the correlation with the o2 sensor and the over-fueling injector.
There is another guy on you tube In which made a video showing usable dynamic test for GDI. He uses the rail pressure sensor that is on the SENT protocol. He uses an arduino to decode the data and convert to a an analog out put for the scope. Then he monitors current for all injectors, the current for the spill valve and the decoded rail pressure data. I was amazed how well the correlation could be made between the pressure drop on the rail When the injector opened and pressure rise when the spill valve was commanded to replenish the rail.
Great video from both you guys. GDI is definitely its own challenges
Either way homie your content is amazing
You have skill. I’m around guys whom have become complacent and if it’s not a pattern failure or something they’ve seen before the cringe and steer clear clear.
Do you think the this could have been seen with current as well?
First time I've seen a Pico used like that. Very cool Jake.
great video , i think the gdi system works better with the pilot injector aswell in the manifold , which helps to keep the valves clean , great test with pico
This was nice! Really like that you tested different tools and methods before and after.
This is another great video, thanks for taking the time to show the differences between scan tools. I was wondering did you get those larger scope leads from AESwave? I bought a set from them a few years ago but they weren't the thicker leads like that. Those are sweet.
Thank you Jake. Good job again. Have a great week.
Great video, thanks for sharing. I am really enjoying your channel, all the best.
Great idea comparing the injector with o2
Got to watch Jake. Will be trying this. Thanks for the heads up buddy.
Really interesting diagnosis, thanks.
I wonder what a pressure transducer hooked to fuel pressure and triggered by #1 coil if the waveforms would show a pattern that could be used to determine flow differences. Their should be a corresponding slight pressure drop on each opening that may show irregularities if flow was increased on a single injector.
Really cool, i like your way in analyzing issues.keep going bro
Excellent video! I like the technique you used with the O2 sensor. I am wandering if we would be able to see it with a wide band O2 sensor? I have not had problems with GDI injectors, but I've been practicing in known good GDI injectors! Looks like is going to be fun since many of them don't have easy access to. Thanks for sharing.
Really cool! The most surprising thing is that a 2019 car still has old school 02 sensors!
Nice work! Thanks for sharing.
That scope capture is awesome
@@autodiagyt that was really cool.. I’m going to use that!! Ty
wonderful video i haven't had to work on but direct injected vehicle and it wasn't a injector issue but will happen sooner or later this really is good info to have
Maybe hard to tell sometimes based on scan tool injector drop test because sometimes they're super low like the 270 kPa and you may think its not flowing enough fuel. Great video
Great video this helped me a lot!
Great job brother your a great teacher.thanks
I had one stuck open was easy to find.. lol and was wife’s car did all 6 oe injectors.. love that tool!!
great video .. did the customer ever approve the vale cleaning job?
@@autodiagyt I hope the customer understands its his come back in the future.
Curious what were the fuel trims before you replaced the injector and was that cylinder showing misfires? Very cool experiment scoping the O2 sensors synced to the coils. Nice work BTW!
am i correct in seeing that at 11:40, you didn't use anything to protect the scope while reading coils on the scope (I.E. potentiometer or otherwise)? Forgive me if that isn't the correct term but im still learning scopes. 8 years as a dealer tech and ive seen this entire time that no one knows how, or uses, scopes so it will set me apart big time. TIA
Bro love the content. Keep it up
Did you do the walnut cleaning? If so could that also be the reason for such a drastic change with the pico results?
@@autodiagyt good to know. I probably don’t use my pico as much as some. I do use my Uscope more than the pico. I tend to do “Most” of my diagnostics through pids and graphing. I do enjoy your videos especially the ones that get into rewriting EEPROMS. But unfortunately for me not something I get to do very often. Keep up the great work!
i like that test
Is that tester specifically for GM products or can it be used with other manufacturers. I liked that you tried other units in your testing.
@@autodiagyt Thanks for the info, I'm always looking for ways to sharpen my diagnostic skills and be more accurate.
Separate the long pipe from thermostat housing reuse the long pipe and replace only the thermostat housing
Hello Jake,
Curious which J2534 box you are using with GDS? Cardaq 3 Plus?
ooh I am a little late to the show this time lol I thought modern cars were more reliable than older ones.. seems the quality aint great just lately.. 👍👍
Grasias
I had to look back at this video to see if you covered it, I got a 2020 Chevy 1500 5.3 That came In from another shop, That has a strange very weak miss fire at idle And underload, Has a p 0300 with misfire counting up on number 1 And the other shop done the usual Spark plug ,wires and coil. When I do injector balance test it shows Bank two drop all cylinders about 35lbs, And bank one cylinders 27 lbs, Number one cylinder at 19lbs It seems as though Number one injector. Is restricted, Have you seen this problem and do you think TSB #16-NA-383 About carbon build up what have anything to do with this.
Hope you enjoy vacation and get back to Alabama.
If you are using a scan tool for those readings only go off one bank to get averages. Fuel trims will effect the readings. So if bank 1 is -10% and bank 2 is +10%, you will see different pressure drops from bank to bank. But honestly the only method I trust is cold engine with AFIT tester. You have a high pressure fuel system but it's giving you pressure drops on the low side while the engine is running, I can't wrap my head around how it's getting these numbers. So try to make friends with the local dealer and try to borrow their AFIT lol. I usually drop the vehicle off the night before and test it first thing in the morning before they get going.
@@autodiagyt short fuel trim on both sides of zero, and long fuel trim is 0 and 2. So that might be the discrepancy between right and Left bank, The closest dealer is 40 minutes from here and customer rather not fool with them again if he can prevent it, The truck has barely over 60,000 miles, and paid for the work that was already done and was told more testing would be needed, The dealer also told him they don't know if any problems problems that GM is having with a 5.3 as per recalls or service bulletins, That's how I end up with it, I appreciate your help and I'll keep doing a few more test and this service bulletin to see if it might help the situation, I asked you before but I lost it what does RLS stand for that shaun was talking about on his podcast, I can't find RPO codes on this truck I don't know where they hid it
@@KANDiagnostics repairlinkshop
Just seen you make my day.. you have comfort face.. I dont know ur culture.. But please please remove the rings from ur ears..
👍🏻👍🏻
I take the oxygen sensor is just a normal zirconia and not a wide band then
Amazing work and results, new subscriber and fan here 😎