2 weeks ago my car threw a code and i used my scanner to see what it was. came up as "System too lean-bank 1" and it also read another code but it just said 'pending' so i erased both codes thinking nothing of them as the car ran fine.
last night the same codes came back up with the CEL. i erased them both again...
wtf is going on here? my first instinct was possibly a clogged injector, i have yet to try some injector cleaner (rc 270cc's) to see if that helps-i wil ltry that soon. i checked all the vaccum lines as well thinking maybe there's a leak somewhere causing to much air going in or something, but everything was nice n tight. also checked all the intake mani. bolts and the gasket, all were kosher.
now, i removed my EGR and had the the VCM tuned w/ hpt to illiminate the CEL for it, could this possibly be the cause, maybe its not seeing the exhaust gases in the 02 readings it should cuz the EGR is no longer hooked up??
or could it possibly be just a bad 02 sensor, or one on the way out perhaps? the rear is the stocker, 96,000 miles, the front i have no idea, it was on my other z for the life it ran for ME that i know of which was 15,000 miles but the car had 85,000 on it, has been on my car now for about 4,000.
My 96 Turbo Z would throw this code. Even thou it was spitting black smoke at the same time. I wondered if it was O2 sensor, but not sure. I had found there was a GM reflash update for 96 year for this issue.
FU Tuning
I have the same code and still have it after O2 change. Was this reflash part of a recall?"
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Call the dealer with your VIN and ask if there are any outstanding recalls on your car. Otherwise, I would replace the O2 sensor and see if that fixes it.
The reflash was not part of a recall. There is a GM site somewhere that you can put your VIN in and it will show any updates for your car.
FU Tuning
mygmlink.com, forgot about that one.
I just changed the PCM in my car and will see how it does... If it still does it I am going to check my fuel pump/fuel filter.. I know the PCM can increase the pulse width of the injectors to cominsate for the Lean bieng picked up by the O2S. This inturn causes the engine to load up on fuel and can cause the car to hesitate.
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hey z yaaa, what was the code number? P0171 or P0172?
I have changed the O2S twice, Fuel Rail, Injectors, and PCM ( I have extras laying around). I still have issue.. I am doing fuel filter Tonight. Then fuel pump this weekend. I'll let ya know if this helps... My fuel pump and filter are OEM, Old I'll let ya know...
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I called in to GM awhile ago on my 98 and luckily no recalls,but had the same issues and replaced the o2 and that was the problem,just pull it out and check it first.
15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
I replaced the Fuel filter just cause it was old. I stil had this isue, i replaced my TPS and i no longer am loading up on fuel and bucking real bad at sustained speeds ie:70mph. I do still have a loss of power an d slight hesitation. I also have to prime the pump up to 3 times if the car sets a while, before it will start. I am replacing the fuel pump thiss weekend.
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If the ECU says you're running lean, but there's black smoke, that reeks of an injector mismatch or no spark.
One cylinder is dumping air and or unburned fuel into the exhaust because either it's not getting fuel or it's not igniting it. As a result, the other three cylinders get more fuel that causes the black smoke, but that one cylinder keeps pumping air into the exhaust. This also tends to make your cat fry.
A vacuum leak will not cause this problem.
A bad 02 sensor will usually report "insufficient switching" if it's getting old. This doesn't sound like a bad 02 sensor.
If your fuel pressure is at fault, your injector pulse widths will be very high.
Does the problem go away in open loop mode (flooring it)?
Are there any exhaust leaks before the O2 sensor?
2002 Cavalier 2200 5spd
I found a bad ground n my car. This ground eyelet has 4 grounds to it. The ground is located on the engine block on the driver front side of the car. There is the battery ground and others here, 8 total i believe. Give these a look and check for breaks. This fixed mine right up.
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have you guys ever thought of a small exhaust leak? if none of the solutions above worked then my guess would be an exhuast leak either in your manifold gasket, or the O2 sensor bung itself, it might even be that your header or manifold might be cracked and a little more air then necessary is hitting the o2 sensor
