What can cause very lean condition on both sides at very light part throttle? When cursing around 1500-2000ish rpm my car leans out too 20:1 AFR according to my AF gauge! When the happens, car stumbles and bucks. I logged it with datamaster and both o2 sensors sit a 057-090 when that happens with injectors pretty much not firing. Give it more throttle, everything clears up, 02s start moving AFR goes to 14.7.....
i flashed my PCM with another file i had just incase and still does exact same thing, so its nothing in the program itself.......other than that car runs great...i am puzzled?! MAP, MAF etc looks fine...il post the datamaster file here in little bit...


P.S

It's not PCM either...put a spare PCM in...problem is still there.....VersaFueler going bad?

 

here is the datamaster file...just look for 02s to be at 0xx-0xx...thats when the car is stumbling and AFR is pretty lean.......

http://www.lt1ultraz.com/miss.uni

 

Sounds like cam reversion.

 

so how do i go about correcting that...readjust the valve lash?!

The car ran great for over 6 months

 

Well you could run it rich in open loop to see if it stops the lean condition and bucking. This might help you narrow the problem down. If it is cam reversion then there is nothing you can do about it other than run the car rich or get a smaller cam.

 

so this just shows up out of nowhere after 6 months? i dont think so

car ran smooth for 6 months.....running open loop / closed loop has 0 effect on the leaning out....it leans out randomly at light throttle and goes back to normal after u blip the throttle.....it doesnt run LEAN constantly

 

What plugs are you running?

 

AD delco FR1LS...there is nothing wrong with them

 

well the stumble is gone...there are 2 things that could have fixed it...il let u know guys know for sure later today

 

THE PROBLEM WAS THE SCREEN ON THE BRANd NEW MAF i have installed.....CAR RUNS FINE WITH THE SCREEN OFF....once the screen is back on the MAF, the car leans out and stumbles right around 1500-2000 rpms...

 

Wow that sucks. I bought a brand new MAF from the same place and its working like a champ. Didn't you just have your old MAF die on you? Any connection?

 

i am goin to try to get another MAF and see how it runs with the screen on it....doesnt seem like the MAF is deffective as the car runs fine with the screen with the blower belt off...