lean spike at cruise

[Crowhater]

I have a 2008 C6 Corvette W/auto. 416CI ls3, 3800rpm stall, 102 intake, full exhaust, injectors, etc.

The car has a len spike at cruise and I just cant find what is causing it. I have checked all my ground wires and attached another ground from the battery to the engine block. Under acceleration the car is perfect. I have attached a scan and the tune.

[Crowhater]

anyone have any ideas?

[Ben Charles]

Yea both your LTFT's and STFT's are both lean, turn off the LTFT's in the tune and then your STFT's will be way off. Dial in the STFT's and you will be good again on AFR.

[Crowhater]

Yea both your LTFT's and STFT's are both lean, turn off the LTFT's in the tune and then your STFT's will be way off. Dial in the STFT's and you will be good again on AFR.

Like this? Is this what is causing the lean spike/miss?

[ingsteve]

1) do not use the cruise for this type of verification
2) the maf is around 3400hz, try to increase in that range the maf of half% to ltft and see if you note some improvements

[Crowhater]

Last night I went through the wiring with a meter and checked everything. I also made the suggested tune corrections but the lean spike was still there. It was not as bad but it was 40* this morning and it seems to be worse when it is hot.

[DSteck]

Try cutting your Closed Loop Proportional or whatever it's called in half. Closed loop will swing wildly on some setups, and it can be exacerbated by poor quality injectors. Reducing the proportional gain can deaden how hard they try to swing.

[Crowhater]

Try cutting your Closed Loop Proportional or whatever it's called in half. Closed loop will swing wildly on some setups, and it can be exacerbated by poor quality injectors. Reducing the proportional gain can deaden how hard they try to swing.

Love the Clutch! We just received the first tripple disc for the ZL1 Camaro. The factory clutch lasted 6 passes before it went up in smoke. They have sent out one other clutch to some guys in FL but they still don't have it working right. It took some machine work to get it to work for us but we did it and it works great.

[Crowhater]

The shop worked on the car all day yesterday and they are telling me they think it might be an injector. They want me to send all the injectors off to be tested. The injectors are only a year old and they are ZR1 injectors. Does this sound right to you guys? The car does drive better and the spike/miss is much better but still there.

[Ben Charles]

Did you ever adjust the MAF curve?

[Crowhater]

Sorry I did not download the current tune. It was very late when I got home and I had to take the airboat with me to work today because I am leaving for the coast.

What did you see in the MAF curve that looks wrong?

[ingsteve]

is the maf curve stock? You need to tune it right according to ltft (not at wot) or wideband

[DSteck]

Run the car in open loop and see if it goes away completely.

[Crowhater]

I have people telling me that my miss is caused by airflow into my cold air intake???? I did install a small plate trans cooler in the bottom opening of my front bumper. The cooler takes up about half of the opening.

[Crowhater]

Ok here is where I am at right now. Last night I cleaned the Maf and my cold start issue went away. The car did not miss that bad on the way home yesterday when it was 78* outside but this morning when it was 50* outside it missed all over the place when I was at light throttle. it does it real bad in 6th gear 60-80mph and it is random.

[DSteck]

Run the car in open loop and see if it goes away completely.

Give it a shot.

[Crowhater]

Give it a shot.

Tried it and the surge/miss/buck, what ever you want to call it did not go away.

[DSteck]

Do you have a log while in open loop?

[Crowhater]

Do you have a log while in open loop?

No