Falling on its face

[theLuiS4]

Wanting to see if I can get some help. My 2010 S4 6MT intermittently falls on its face above 6k rpms. Feels like misfires. Power just randomly goes away and comes back. Far worse when downshifting from 3rd to 2nd. I don't get any codes but I just check using my cheap code reader. Here goes my datalogs if anyone has some time to check them out. I have a 3rd to 2nd downshift and just 3rd gear from 2k to redline.

https://datazap.me/u/luis6827/log-1605224527

TIA!

[bajan01]

What tune, pulley ratio, fuel, clutch, plugs, plug gap, sc belt brand?

STFTs are waaay low.

[theLuiS4]

IE DP, 93 octane, not sure what clutch tbh. Gates SC belt. 179/57 ratio. Autotech hpfp. S4 Matty ported TB. .026 spark plugs that I just recently replaced.

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[bajan01]

You spraying methanol? She’s running super rich.

[theLuiS4]

No. But I just upgraded the HPFP. You sent me yours that you had. Lol. I also got p2404 pop up twice. I thought maybe it was the cam follower so I replaced it. It's still doing it though just no p2404 yet.

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[theLuiS4]

Also I should note that around the time I upgraded the hpfp I also started losing a bunch of coolant. No external leak and doesn't seem to be going into the oil. So I'm assuming intercoolers although I'm still unsure if this is fuel related or not.

[bajan01]

Issue with evap system (P2404) needs addressing.

Coolant loss could be intercooler cores or water pump.

[wes8398]

#1 - I'm no pro at log reviews, but I've been teaching myself along the way for the last year or so.
#2 - Very quick review on my tiny cell screen shows that your bypass valve is starting to open at 6700rpm as your "actual" boost is creeping up to your "commanded" boost. By the time you let off at 7150rpm, the bypass is almost 12% open.
This appears to me to be an issue of your tune not requesting enough boost to keep the bypass valve closed all the way to redline.
I don't see any huge issue with the rest of your readings; including any other reason that your bypass valve would be opening. Spark advance is maybe a little lower than ideal, but that could be a fuel thing, or a tune thing... Or a mix of both.

Now, why it feels like it's "falling on its face" at 6,000rpm... I don't see an explanation for that here. Unless I'm missing something on this little screen, I think everything looks good at and around the 6k rpm mark.

[theLuiS4]

I believe it has been addressed when I replaced the Cam follower. It hasn't come back since. But I guess it might idk. I may need to do another log.

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[wes8398]

You spraying methanol? She’s running super rich.

I thought at or near .8 wasn't uncommon under WOT/redline conditions on the 3.0t...?

[wes8398]

#1 - I'm no pro at log reviews, but I've been teaching myself along the way for the last year or so.
#2 - Very quick review on my tiny cell screen shows that your bypass valve is starting to open at 6700rpm as your "actual" boost is creeping up to your "commanded" boost. By the time you let off at 7150rpm, the bypass is almost 12% open.
This appears to me to be an issue of your tune not requesting enough boost to keep the bypass valve closed all the way to redline.
I don't see any huge issue with the rest of your readings; including any other reason that your bypass valve would be opening. Spark advance is maybe a little lower than ideal, but that could be a fuel thing, or a tune thing... Or a mix of both.

Now, why it feels like it's "falling on its face" at 6,000rpm... I don't see an explanation for that here. Unless I'm missing something on this little screen, I think everything looks good at and around the 6k rpm mark.

Further to ^

Now that I see you're running an IE DP file on a pretty conservative pulley ratio, I'm even more surprised that you were reaching their commanded boost...

[theLuiS4]

Issue with evap system (P2404) needs addressing.

Coolant loss could be intercooler cores or water pump.

It could be the water pump even if it's not leaking externally? I'm hoping it's the intercoolers creating problems if they're leaking onto the plugs.

[theLuiS4]

Further to ^

Now that I see you're running an IE DP file on a pretty conservative pulley ratio, I'm even more surprised that you were reaching their commanded boost...

Thanks for the reply. Another thing I'll do is remove the tune and see if it does it without it. I did flash back to stock but then I flashed back to DP without checking to see if the problem remained.

[theLuiS4]

Just a quick update-->

So I removed the tune and went for a drive. Idle is still somewhat lopey. And the stumble is still there downshifting from 3rd to 2nd. Got home and checked oil. Noticed that the level is actually going up. Suspecting a leaking hpfp (again) i pulled it out and took it apart. The autotech piston was seized to the autotech lower sleeve. I got them to come apart by tapping the piston out with a hammer. I'll be lubricating everything and trying it again. I attached pictures of the parts. They look like they weren't getting lubricated whatsoever.

[wes8398]

I don't have any experience messing with a HPFP, but it looks like you're on the right track, anyway. Curious to see how this goes.

[theLuiS4]

I don't have any experience messing with a HPFP, but it looks like you're on the right track, anyway. Curious to see how this goes.

Yeah I'll update this as I've seen guys post about similar issues. I find the lack of lube strange since I lubricated everything with a light film of engine oil. If anyone with experience replacing their internals can chime in and let me know what you used for lube that would be awesome. Someone said to use fuel in another post I was in. Will try it this time and hopefully this can finally be done.

[bajan01]

Yeah I'll update this as I've seen guys post about similar issues. I find the lack of lube strange since I lubricated everything with a light film of engine oil. If anyone with experience replacing their internals can chime in and let me know what you used for lube that would be awesome. Someone said to use fuel in another post I was in. Will try it this time and hopefully this can finally be done.

When I did mine I lubed with oil on the oil side and fuel on the fuel side.

I have since installed a new, fully assembled pump from Autotech on my SQ5...wanted to go with a new one as the factory pump had 60k miles on it and seemed to be losing pressure up top on WOT pulls. I will say that the person that I gave that pump to (not you as you got the one from my S4) told me that it works just fine for his slightly lower pulley ratio application...so at least I know that I assembled it correctly.

It seems like the part common to your problems is the piston itself. Perhaps you got a bad one, one out of tolerance.

[djn876]

Talk to autotech and they may send you a new one based on what you are seeing. But yes, should be lubricated with fuel.

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