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Engine acting funky

N

Nchristopherson

New member
This is a problem I have been having for a while, and I have tried a lot of things with no luck, but hopefully having more information may help solving it.

When my car is at idle and cold start, it does it's usual thing just fine, no weird idling or anything like that. Once it gets hot though, it is a different story. It will stay running fine because it's in closed loop. But if I turn the car off and turn it back on, it idles very lopey for the first minute of running. It feels like it has a big cam in it. My guess is because the PCM is in open loop. My wideband shows such a high AFR, it doesn't even register on the gauge. After a minute, it steadies out and the AFR comes back down to around stoich, and does its dithering. The effect is that my LTFTs shoot up to 16.4. If I command the car back into open loop again, it will keep loping and the AFR will shoot up again. If I turn the AC on, it will come down to about 17:1.

Also, if I am at a stop and press the pedal quickly, it will almost stall the car.

Could this be anything other than a vacuum leak? I am not sure what type of vac I should be pulling at idle, but I typically see between 17-18 inHg.
 


Sealed off the throttle body inlet and blew smoke into a vacuum hose.. No leaks anywhere, holds pressure very well. When running at idle, MAP reads 33kPa like my mom's impala. I'm shocked that it's not a vacuum leak, but I think after that, it's safe to say it isn't.

I did put 60# injectors on my car and used ZZP's tune, could that be causing an issue? I just spliced the EV1 connectors where the EV6 were and just color matched the wires, which I think is fine. I just don't understand why it is running so bad.

Other things I noticed:
- Open loop, LTFTs at 4.7%
- Closed loop, pegged at 16.4%
- The IAC position on my car is 20 lower than on my mom's impala (20 vs 40).
- Everything else seems to run fine except the O2 sensor dithers a lot slower on my car, but idk if that is because of a tune.

Also, this is getting to the point where I'll pay good money, a case of beer, food, whatever, for someone to come help. Name your price! Located in northern IL / southern WI.
 
ZZP canned tunes, yeaaaaaaaaaaaaaaaa! another happy customer for the books.

i say put your stock injectors back in and the stock pcm, lord i hope you have it still, then see whats going on after it all learns again.


whats your mod list? i dont see it.
 
I keep everything fortunately :) and when I asked them about that, they seemed to dodge my questions and shift the blame to me.

Mods list:
- 02 Grand Prix GT
- 60# Siemens Deka injectors
- ZZP Z3 Turbo kit (Intercooled)
- Front Plog
- PRM
- AEM Boost controller, AEM Wideband
- Stock wastegate setup (8PSI I Believe?)
- AEM high flow fuel pump (For e85 switch later on)
- Blocked off EGR, Catless, Breather, 180Tstat, etc. etc..
- HPTuners also.
 


ok, thats a list of goodies. you cant run it on the stock pcm at all.

the best advice your gonna get is to get it in car tuned. or better yet, buy a tuner and learn how to tune. its not that hard really. 300 bucks more to do your own tuning is nothing after what that turbo ran ya already im sure.

we got another member here with a turbo and a zzp canned tune, and his ltft's are all f ed up as well.

same for a local near me, zzp 1.0 and his lifts went +16.
 
Unbelievable. I put the stock injectors and stock tune back on the car and it runs beautiful. I definitely think the injectors are fine, they were brand new. So that leaves the tune. Wtf ZZP...
 
dont leave it like that, the timing is way to high in the gt files and boost.

the injectors need to be fine tuned is all. if you have hp tuners you can do that.
 


Talking with ZZP to get the tune straightened out and the guy believes something is funky, so he said to try doing a VE tune by unplugging the MAF and recording without getting into boost (since GT MAP is limited to 100kPa). However, the car doesn't start with the MAF unplugged. Is this tell tale of another problem, or is it tell tale of a bad tune? Lol
 
try starting it maf unplugged when its cold. if its warmed up it will want the maf to run. when cold it runs off the pcm's settings.
 
Ok. Also, I apologize I never followed up on the heads cause I was in the middle of moving out to school and haven't had a chance for play time until now. They got out here quick and look great, thanks much!
 


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