O.K. here's the scenario. My car has been down for about a month now and I have tried everything I can think of to fix it. It idles up and down and runs very rich. It also gives me a lean O2 code. here is what i have done or replaced:

O2 sensor is 1 month old
New Wells MAF
Complete tune-up
Fuel pressure at 48psi
No apparent vacuum leaks.
Distrbutor pickup is good

The only things I haven't checked are EGR(no code) and IAC.

Please help. I'M GOING MAD!!!!!!!!

 

Can anyone help?

 

Do you have any scan tool data?

 

Where in Nor-Cal are you ?

Whats the TPS Voltage look like ?

 

I will have scan data tomarrow. I ran it again last night and it still runs SUPER rich, but I couldn't get it to throw a code. i don't think it's going into closed loop. The scanner will show that tomarrow. TPS is right at .54V
i'm in Santa Rosa

 

Well I finally got some scan data. The car runs in closed loop now and is still rich(o2 doesn't switch rich/lean). Also there are no codes. I can't get it tyo give a SES light. Here's the scan data:

Air Divert: ON
Air Flow: 9-10 G/S
Air Switch:OFF
Batt. V:13.9
BLM Cell: 4
BLM:108
Collant temp: 92C
EGR pos.:ON
EGR DC(%):0
IAC:9
Idle RPM:75
Injector P/W: 1.5-1.6
Integrator:100
Knk. Ret.:0
Knk. Sig.:NO
Loop: Closed
LV8:60-64 (switches)
MAF:9 G/S
MAT: 34C
o2 cross: 0
o2 state: Rich
o2 V: .81 (doesn't switch)
PPSW: 13.0
Prom ID: 2391
RPM: 800
Spark Adv: 24*
TPS: .48

All these were taken with the car at operating temp. I also checked the injector wires with noid lights, and they all are fine.

I am completely baffled by this problem, and I am running out of solutions real fast. Any help I can get would be greatly appreciated. Thank you.

 

Can anyone see anything wrong with the scan data?

 

That Data was taken at idle ?

 

Yes, all that data was taken at idle with the car at operating temp.

 

Are you sure it gave you a lean O2 code?
Did you mean to say rich O2 code?
A lean code is set when the O2 signal voltage remains below .2 volts for 50 seconds. Your scan data reads 0.81. I'll assume that
it is running rich...rich exhaust indicated by greater than .7 volts for 50 seconds, and in closed loop.

Try lowering your fuel pressure.
Have you had your injectors balanced and cleaned?...especially if the engine is a high mileage one. I would do that next. This way your injectors will be balanced, and a possible leaking injector will be fixed.
Does your tachometer read higher than normal while driving?
Your canister purge could be saturated.
Check your TPS signal for varying output.

There are other possible solutions...such as ECM. YOU check that I believe by disconnecting the O2 sensor, then grounding it. If O2 volts drop below .35 volts, then ECM is ok.

 

Can you Tell us a little more about the car ?

Your Dead rich at idle.

Santa Rosa I sorta far from here, Was going to offer to come By and Have a Look.

We really need to know about the car, year, Any changes, ect.

You didn't put bigger injectors in did you ?

 

It was giving a lean code, now it won't give any code. And the SES light works. The injectors were cleaned and flow tested back in March when I rebuilt the motor. I was given a flow sheet, from the place that did it, and they were all flowing very close at the time. The injectors have about 105,000 mile on them total.
The car is an 88 IROC TPI 5 speed. Edelbrock TES, Crane Cam(208/214, 438/452-112LSA), Holley AFPR, New MSD cap,rotor,coil,wires, Spintech exhaust, high flow cat, k&n, pulleys, ported plenum. I think that covers the majority of mods.
Bort, I appreciate you wanting to come out, where are you from?

 

Anything else I should check?

 

Check your IAC...clean it.
What was wrong with your old MAF? If it's fine, put it back on.
Do some searches for Wells MAF. I think I have read others having some slightly similar problems using Wells MAF sensor.
Did you readjust your fuel pressure? What happened once you did that?
Is your O2 sensor a GM replacement? Should be
Recheck for vacuum leaks. Check PCV valve. That shoul be a GM piece, too.
Do you have a vacuum guage? What is vacuum at idle?

 

IAC is brand new, also cleaned the housing when it was replaced, as well as reset minimum air setting. Wells MAF gave the same results as the factory Bosch style one that I have. Lowering the feul pressure seemed to have no affect whatsoever. I have a Bosch and Napa o2 which work the same in the car. PCV allows me to blow through it(in correct direction only) and vacuum is at 18-20 with fluctuating idle.

I'm about to take the car somewhere to get fixed because I'm gonna shoot it here soon. I feel as though i've exhausted every possibility available.

 

Did you reset your ECM after making some of the changes (disconnecting battery cable)?

How have you checked for vacuum leaks?
Do you have a new battery?
Alternator charging properly?

Maybe someone else will jump in and help you out.

I'm not sure how this would afftect idle...but if your o2 sensor code is a lean code:
Make sure o2 sensor wire, pigtail isn't touching exhaust manifold...
Exhaust leak can pull air from outside in past the sensor.
Vacuum or crankcase leaks can cause lean condition.

But that doesn't make sense to me to have a lean code, but be running rich as you are.

Have you checked out the ECM?

Maybe someone else will jump in and help out.
Hope you get it fixed...welcome to the 3rd gen world

Edit:
I'd try another O2 sensor, too.

 

TTT
Curious if you have gotten this figured out...