Troubleshooters unite! Few issues since engine build, input appreciated

[Quebster]

DMM - Does that stand for digital multi meter? If so, I do have one. All great suggestions, thanks so much everyone for the ideas so far.


So, should I hold off on replacing the injectors you think? In my research a botched injector(s) could cause all of the issues I'm having as well. HPFP does make sense also. did anyone watch that video I linked?

 

[Wrath And Tears]

Yup that's exactly what I meant. You will need some back probes (needles that plug into the DMM more or less, you insert them into the back of the electrical connector to prevent any issues (although I've put them into the front of an electrical connection with out damaging the prongs).

Watching the video now. If you already have the injectors (and can't or don't plan on returning them), there is no harm in replacing them. Otherwise let me find some diag steps for the injectors for you to follow.

Stupid question, have you done a throttle body adaptation? After watching your video, it has similar issues.

Edit: So you have no misfire faults? Can you log misfires for us and see what cylinders are missing?

2nd Edit: Sorry for not starting with the basics, that was stupid of me.

 

[Quebster]

I believe I’ve read that the throttle body adaptation takes place pretty much each time you turn the key on the Mk7’s


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[Wrath And Tears]

I believe I’ve read that the throttle body adaptation takes place pretty much each time you turn the key on the Mk7’s


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Yes but that is not an actual TBA, that is just it mimicking the last movements it did. Sometimes if you are having issues, you need to manually do it. It is suggested to clean the throttle body before doing the adaptation. That is assuming it can be done. UDS (the ECU... language) that was implemented with the MK7 has brought a lot of changes, and how you do things are different. ECU -> Basic settings -> scroll box -> TBA.... I think.

Did you see the edit about misfires?

 

[Quebster]

I have tried the actual TBA once a while back, but I can try it again.

No, I don’t have any misfire faults. Though I can log misfires if you’d like


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[Quebster]

The SAI fault could very well be the cause. False or un-requested lean mixture could make it dump extra fuel and run rough/stall. But I’m not 100% sure where the extra SAI air is injected honestly so this is just speculation

Btw had a thought this morning that I could always just unplug the wire to the SAI valve and see what happens driving around like that.


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[Quebster]

What if we focus on the one consistency I had at the track on Tuesday... every single time I came off the track, parked and was letting the engine cool, I would start to get the rough idle and ultimately the engine would die.

What would cause the engine to do that after every session of driving really hard?

Re-posting the vid for reference:

https://youtu.be/QtF-Tc0wQOQ


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[ChrisMk77]

I would service and ultrasonic wash the DI injectors.

 

[donefor]

Rodents are the number one cause of strange electrical issues.

Quoted for posterity and truthiness.


Interested to see what turns up to be the origin of this problem, it's gotta be a special kind of frustrating after the build.

 

[sprout703]

Any updates? I hope you got it sorted out.

 

[Quebster]

By the way, in case anyone comes back across this... My aftermarket fuel pressure regulator was at fault here. Well, actually, I was at fault, for not adjusting it. This is the one that comes with the Precision Raceworks Stage 4 kit, with dual Walbro 450's. I had to increase pressure because it wasn't keeping it up properly at idle. All there was to it!

Fortunately it was only during idle that pressure was low. During WOT pulls we had plenty of pressure.

 

[Gvazquez]

By the way, in case anyone comes back across this... My aftermarket fuel pressure regulator was at fault here. Well, actually, I was at fault, for not adjusting it. This is the one that comes with the Precision Raceworks Stage 4 kit, with dual Walbro 450's. I had to increase pressure because it wasn't keeping it up properly at idle. All there was to it!

Fortunately it was only during idle that pressure was low. During WOT pulls we had plenty of pressure.

What would cause the cylinder pressure too high code from that?

 

[Quebster]

What would cause the cylinder pressure too high code from that?

That is still an unknown, even know. My best understanding is it has something to do with the Mahle pistons. They do change the compression ratio a tad and I'm betting the ECU just freaks out a little every now and then and it's a non-issue. I've only had it happen once recently so it's not too common for me anymore.

 

[JerseyDrew77]

That is still an unknown, even know. My best understanding is it has something to do with the Mahle pistons. They do change the compression ratio a tad and I'm betting the ECU just freaks out a little every now and then and it's a non-issue. I've only had it happen once recently so it's not too common for me anymore.

Did you go with the standard size of 82.5 mm or did you go up in size to the 83 mm pistons?

 

[Quebster]

Did you go with the standard size of 82.5 mm or did you go up in size to the 83 mm pistons?

I stuck with 82.5mm, I didn't have any damage to justify boring them out. We just honed the cylinder walls for a fresh mating surface.