2010 VW GTI 2.0 TSI Injector
01 Engine ECM
00768 Random Cyl Misfire Detected (Status Active)
00772 Cyl 4 Detected (Status Active)
08213 Intake Manifold Runner Position Sensor/ Switch Circuit Range Performance (Status Active)
00770 Cyl 2 Misfire Detected (Status Active)
00771 Cyl 3 Misfire Detected (Status Passive)
I was contacted by my wife's boss's son about a misfire on his GTI. He had told me that he started having a slight misfire under load. He supposedly replaced spark plugs and coils, but still noticed a misfire only on cyl 4 so he took it to a Euro specialty shop in the area. The shop wrote it up for a couple oil leaks, tail light out, stated the timing chain does not have the updated tensioner and just performed a fault scan and said the vehicle will need to go to another shop that has the factory tooling to run a diagnostic test plan. This is where I may have diverted from keeping it simple and assumed to look at Fuel/Mechanical. I get to the vehicle and run Fault scan and following DTCs were found and saved. I delete the codes because I don't know if these codes have occurred because of others messing around. Measuring block 015 was observed for misfire counters and right as the vehicle is started number 4 counter increases. My first two tests are to use the Escope RC test and Misfire tool. The procedure for RC test is performed as well as the misfire tool, RC tests green with no noticeable differences, misfire tool determines that cyl 4 is our missing cylinder. I should also note that FRP actual and desired were observed and both very closely matched one another. After I went through RC test and identify the missing cylinder I found that the intake manifold code had set right away and cylinder 4 misfire. Of course putting full trust in this owner that the plugs have been replaced, and seeing the coils are new red top Bosch coils I don't even think about ignition. I go right to looking at the current of the injectors. Now I've been studying the scope pattern of GDI injectors and really have only scoped a piezo off a N63 engine and one solenoid type off a GM 3.6, but I know I should see 3 stages a boost stage, pickup stage and hold or modulation stage. After checking all 4 I don't see anything that really concerns me, but I am somewhat concerned about one particular capture of injector 4 I got once and you will see the photo of what I'll ask you all about after I wrap this up. So after looking at these injectors I decided to just examine these plugs and I can see that these bad boys look old, they are NGKs, they have the brownish orange discoloration that you see around the base of the porcelain of the plug that hasn't been changed. I decide to swap number 4 coil and plug to number 2 and let the engine run. Right away number 2 misfire codes. I erase the faults and started it again and right away number 2 misfire and the intake runner fault set. I swap just the coil back to 4 and of course the misfire moves. I ask him to grab one of the original coils and of course the engine is no longer misfiring. The codes are erased and adaptation reset.
Now to my question for you all, in these photos of the injectors do you see an issue with them? I'm especially curious about #4 where it looks to have good amperage on boost stage and waveform looks decent till you get to the hold or modulation phase. The “text book example” waveform is from #2.
To better compare all 4 injector's current draws, tie rap all of the 4 injector B+ wires together or all 4 injector ground wires together, then put your amp clamp around the wire bundle and you'll see all 4 injector current draws. On another channel, scope the injector one B+ wire voltage, as your sync. Your capture will look similar to this GDI waveform.
Thank you ray, I was thinking would it be possible to do that with GDI injecors As it is with traditional port style. I went right to the connector for them at the intake manifold and I found it difficult to cut open what little I was able to In order to just get my amp clamp in there.
Where the access to the GDI wires is difficult, I would tie rap the suspect GDI B+ or the ground wire along with one of the other injector wires, to compare the current draws of the 2 injectors. You still need to use another channel to probe one of the injector's B+ or the ground wire's voltage as a sync.