I just had a new exhaust put on and after resetting the battery it feels like my car just forgot the reflash. It leans out as soon as I go into boost and misfires occasionally. I replaced the pre cat o2 sensor and spark plugs and nothing.
If I drive it for long enough it will start dumping gas and leave my wideband at a solid 10 and will even flood out from all the gas.
At idle my vacuum and A/F are pretty normal, the engine just has a bit of a shake to it.
Anyone heard or seen anything like this?
Exhaust leak before the O2 sensor. Unplug the O2 sensor electrically and observe whether it runs smooth.
Another extremely probable cause is a coincidental vacuum leak.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Checked for exhaust leaks at the header and replaced the gasket with a brand new one and replaced the o2 sensor. Uplugged the sensor but still ran the same.
Vacuum gauge is good.
In park or neutral the car runs okay at idle, but when I'm in drive or reverse it misfires and bogs worse than ever. The wideband goes pretty crazy, bouncing from 13-17. When I rev the car in park the wideband stays at 14-15 even at 3500rpms.
I'm beginning to think it's a fuel problem. Car has a new fuel filter and racetronix pump.
Anyone know the signs of a bad ignition control module?
Update: fuel pressure and regulator are good. Solid 60psi and a solid 47psi at idle.
When you disconnect the battery it resets the long term fuel trim and short term fuel trims it takes a while to re adjust them correctly.
SLO CAV (the autoxing one) wrote:When you disconnect the battery it resets the long term fuel trim and short term fuel trims it takes a while to re adjust them correctly.
Please... the STFTs update instantly and very quickly (have you ever used HPTuners or any other tuning software and monitored a vehicle?), and undoing the battery will make no noticeable difference like this.
Andrew Steen wrote:Vacuum gauge is good.
Doesn't matter, boost leak test it. I've encountered every type of vacuum/boost leak there is, and the only definitive guarantee check is pressurization.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
Curious.....why did you "reset" the battery after changing your exhaust?
GMR has got nothing on this
The STFT updates instantly, all the time, unless in power enrichment. If the STFT is over/under 10% for more than 10 cycles of the motor (milliseconds), changes will be made to the LTFT. When the battery is disconnected, the LTFT is reset (back at 0 if it isn't already).
I unhooked the battery to get rid of a check engine light I had from driving with bad o2 sensor on the way to the exhaust shop.
I got the car to be drivable now. I will misfire under boost still and I can't figure out why. I tried new plugs and regapped them down to .032
I also did a compression test and tested for any vacuum leaks and both are good.
I'm thinking maybe my injectors are clogged because of how lean the A/F gets when I start getting into it.
Andrew Steen wrote: II'm thinking maybe my injectors are clogged because of how lean the A/F gets when I start getting into it.
I doubt it.. I bet your tune is off and needs some work.....
P&P Tuning
420.5whp / 359.8wtq
It's tuned with the GM reflash and has the stock pulley.
Andrew Steen wrote:It's tuned with the GM reflash and has the stock pulley.
So i was right... The Reflash sucks.....
P&P Tuning
420.5whp / 359.8wtq
