Inconsistent AFR

[tucknuts]

I have done a few hours of Maf tuning and have been recently been working on PW. Yesterday after a few logs and small corrections in pw, in the middle of the log(at least 20 min into the log) I started going really lean (18.xx). Since then I have cleaned the maf, recalibrated the AFR sensor, tried multiple tunes w/ different maf and pw values and I still can't get this thing to settle down. To compare, before this happened I stayed in between 14.5 and 15.2 at idle, now I'm in the 12.xx's and sometimes 16.xx's. Also, for some reason I command values other than what I should be commanding. Sometimes I will command 14.1 and even as low as 10.2! My stoich is set at 14.7 and my pe at 11.7. I've never seen it do this before, it doesn't make sense.

[Ryze]

I have done a few hours of Maf tuning and have been recently been working on PW. Yesterday after a few logs and small corrections in pw, in the middle of the log(at least 20 min into the log) I started going really lean (18.xx). Since then I have cleaned the maf, recalibrated the AFR sensor, tried multiple tunes w/ different maf and pw values and I still can't get this thing to settle down. To compare, before this happened I stayed in between 14.5 and 15.2 at idle, now I'm in the 12.xx's and sometimes 16.xx's. Also, for some reason I command values other than what I should be commanding. Sometimes I will command 14.1 and even as low as 10.2! My stoich is set at 14.7 and my pe at 11.7. I've never seen it do this before, it doesn't make sense.

what vehicle is this for? engine?



how much gas is left in your tank when this happens?

[Bill@HPTuners]

Car is probably in open loop & running on your open loop tables, impossible to tell without a scanner log while logging open/closed loop fueling & commanded afr.

[tucknuts]

Vehicle is a 2005 Cobalt ss/sc

[tucknuts]

Hey guys, I"m still having this problem. Any insight?

[Bill@HPTuners]

Log looks fine to me, what am I supposed to be looking for

I mean the beginning of the log you are in open loop startup which is normal.

There are a couple points where you go into pe but those appear fine as well.

[tucknuts]

Here is another log. During the begining of the log I go into OL-fault. What is causeing this? Also should my injector duty cycle ever be at 0%

[my_bd]

post a tune.
almost looks like you are in permanent pe mode or something like that.
add the pe status bit to your logs too.

[Bill@HPTuners]

Its not in any permenent pe mode when hes at 14.7:1 commanded afr for 2300 of 2450 frames.

Also did anyone notice his B1S1 o2 sensor is dead? I don't think I see it switch once in the entire log. Also his trims are pegged positive the entire log.

There are more issues with this vehicle then the tune

[tucknuts]

Also, i didn't mention i regularly get P0135. Is my O2 sensor going out, making my computer go crazy?

[Bill@HPTuners]

If your O2 sensor is not reading properly it will make you go into & out of closed loop fueling so yes if your o2 sensor is on its way out or making a bad reading it can cause all kind of issues.

[tucknuts]

problem solved, thanks for the help.

[tucknuts]

New problem
When I turn the car on and I reach 900rpm, which is my idle, it goes really lean and bucks and surges for 10 to 15 sec then somehow corrects it self. Why is it doing this?