Engine Cut Off?

[jasqi]

I’ll state first that last night I hit about 95 on the freeway and the car was hitting boost and running perfectly normal. This morning was pretty foggy and I warmed the car up for the 15 mins I typically do and drove conservatively for the next 5. After I hit operating temp I did a small pull, nothing crazy probably like 10-12 psi. Out of nowhere it felt like the engine power cut off or something, it felt like somebody full locked my brakes and the car almost threw my face into the steering wheel. Then it drives fine, did another small pull to make sure I wasn’t crazy and it did it again. I have literally no idea what this could be, I just finished fixing a blown out intercooler and the symptoms are nothing like what that huge vaccum leak caused me. It doesn’t present itself at low boost. Only codes are the Cat code and an EGT sensor malfunction, but I’ve been getting those for awhile and it always drove fine with them on. Any advice or ideas would be greatly appreciated. I’m hesitant to replicate the problem and blow my engine or something so I can’t really provide much more info.

[VespaGTS]

I’m curious why you haven’t fixed the EGT code and O2 sensor code? Do they not add to the problem?

 

 

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[jasqi]

I’m curious why you haven’t fixed the EGT code and O2 sensor code? Do they not add to the problem?

 

 

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No it’s just side effects of having a catless downpipe and constant highway driving, I’ve got the resistors to do it just gotta find the day. It doesn’t send it into limp mode or anything like that though, or affect anything for that matter actually.

[jasqi]

Update: Drove it this morning and didn’t even enter boost and it did it once or twice, except a lot less harsh. Noticed my MAF reading hit 300g/s and that’s without even entering boost. Bad or dirty MAF?

 

 

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[whitexc]

Did a boosted connection come apart by chance? Vacuum line to something? Maybe your little test session on the highway was enough to pop something.

 

That will give you all sorts of grief. Ask how I know.

 

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[jasqi]

I can definitely check, but I had a fully blown intercooler and it was bad enough to stall the car out sometimes. Even when I hit boost with that it wouldn’t full on stop out of nowhere. With this the car starts up fine and drives mostly fine up until I give it a little more throttle. When I watched my MAF reading when it’d almost enter positive boost the MAF reading would jump to a bunch of different spots and hit 300 g/s out of nowhere.

[whitexc]

I would check for boost leaks and vacuum lines that may have been moved around. You just installed this new TMIC correct? How many miles since ?

 

Any other codes popping up?

 

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Edited March 3, 2022 by whitexc

[jasqi]

No I installed it probably a month or two ago, all was well after it was installed. Checked the end tanks today and everything looks good, looked over the vaccum lines and everything looks connected. Also yeah no other codes and I reset the ecu today and there isn’t a check engine light at all anymore, but it still continues to do this. I notice every drive it happens the MAF will cap out at 300 out of nowhere.

[jasqi]

Could not find any vaccum leaks, it warmed up the past 2 days and it fixed itself. This morning it snowed and on my 2nd drive today it started doing the same symptoms. No boost, maxed out MAF at slight throttle, and cut off. Also an especially rough idle. Took some datalogs I might be able to share. I’m thinking dirty MAF as my CAI reaches down below the fender, and I have no bumper or fender liners on right now, and we’ve had some nasty road grime lately. Let me know what y’all think. If not MAF maybe plugs or coils?

[jasqi]

Could not find any vaccum leaks, it warmed up the past 2 days and it fixed itself. This morning it snowed and on my 2nd drive today it started doing the same symptoms. No boost, maxed out MAF at slight throttle, and cut off. Also an especially rough idle. Took some datalogs I might be able to share. I’m thinking dirty MAF as my CAI reaches down below the fender, and I have no bumper or fender liners on right now, and we’ve had some nasty road grime lately. Let me know what y’all think. If not MAF maybe plugs or coils?

 

 

Just rechecked codes and I got a P0171 (System Too Lean “Extreme Fuel Trims”) so I’m thinking MAF.

 

 

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[whitexc]

Yeah, see we are chasing our tails here. This is the first I have heard of the open air filter in the fenderwell.....without liners?! That's not good IMO. Clean that MAF for sure but I would ditch whatever setup that is and go stock air box. They work.

 

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[ttnio]

i wager a boost leak...

[Pleides]

Just rechecked codes and I got a P0171 (System Too Lean “Extreme Fuel Trims”) so I’m thinking MAF.

 

 

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I had a massive vacuum leak when I got this code. Turns out I forgot to connect the vacuum line to the BPV when taking stuff apart.

[jasqi]

I’m almost completely ruling out boost leak as the intercooler one I fixed forever ago ran fine. The car also seems to run normal when it warms up outside and the only times it appeared was a cold foggy day, and a cold day today in which it snowed. Also I have the fender liners and bumper and what not, I’ve just had them off for a minute to sort out some body work, I plan on keeping the CAI, I figure I’ll just give the filter and MAF a good clean and reinstall the fender liners and what not. Also boost leak wise, I’ve inspected the intercooler, all BPV lines, throttle body hose, turbo to intercooler connection, T connector, almost every single one and all look good. I’m also still pulling a good vaccum at idle, unlike when my intercooler blew out.