95 GT running VERY rich

[tmacie]

I have a 95 GT that is running VERY rich. Its been tuned up, timing is set to stock, maf cleaned then replaced, TPS set to .98, Vacuum lines replaced, PCV changed along with grommet and screen, intake charge sensor changed, Coolant temp sender changed. Fuel pressure is at 32. EGR removed.
KoEr test shows codes 136,171,172.
The rich condition is right from initial startup on a cold or warm engine. The car also idles very rough. It has a "hanging" idle issue as well. This issue is worse when the IACV is plugged in. IACV is new and I've tried a restrictor on it.


Thanks,
Travis

 

[HISSIN50]

Why was the FP set at 32? One generally sets the simulated WOT pressure (generally at 38+ PSI).

You're tossing lean codes. Are the O2's reading properly?

 

[tmacie]

FP is 32 @ idle. Its up around 35 at WOT. I don't have access to know if the O2's are reading proper.

 

[HISSIN50]

The stock WOT setting is ~ 37-38 PSI. You might want to change the setting.

A DMM is all that's needed to check O2 function.

 

[tmacie]

Just curious why id want to raise FP if the car is running rich?
I'll look up the procedure for testing the O2s. Thanks.

Travis

 

[Adam95GT]

Because that is a lean code not rich....

 

[tmacie]

Heh....those codes will get ya. Any more ideas anyone?

Travis

 

[fordtech28]

since its fuel related have you changed your fuel filter? Also check the pressure with and without the vacuum house attached to the fuel pressure regulator it should be around 38-40 with the hose off and 32-35 when its on adjust as needed

 

[tmacie]

Filter is brand new. Pressure with hose on is exactly 32-35. I have not measured with the hose off yet.

 

[toyman]

What exactly do you mean by "tune up"? There is nothing mentioned that would indicate that a tuning chip is necessary or did you just mean a basic tune-up, plugs, wires, cap, filters and rotor? TPS are not adjustable on the SN95's unless there is a different TB installed. What was the TB volt reading before the adjustment? O2 sensors don't last forever, the car is 15 years old, just change them.

 

[tmacie]

not a tune....but a tune up. plugs wires, cap etc. TPS can be slotted to move a little on a stock TB. Before adjustment was 1.16, after is .98.

Travis

 

[tmacie]

Also as far as I know, when the car starts up from cold the computer ignores the o2 sensors until the engine is warm. So in that case if it really were the o2 sensors the car shouldnt run extremely rich until it was warm.

Travis

 

[HISSIN50]

The O2's can be ignored. Fuel trims are learned over time (including OL trim, which is then applied to other OL occasions, like start-up) and if the O2's are bad, the learned trims would be off.

You noted your car is running rich. What kind of A/F ratio is your WB showing? That's the way to know - one's nose is not an accurate A/F gauge.

Testing the O2's will take about 5 minutes if you choose to check them over.

 

[Chythar]

Just curious on removing the EGR. Did you have a blocker plate where the EGR was? Is the passenger header sealed properly (after removing the EGR pipe)? Is it possible you have a vacuum leak there?

And just to re-state what toyman said, the TPS on the 94-95 cars is not supposed to be adjustable. The computer will read the TPS setting at start-up, and use that as the baseline. If the TPS is too far from .99V at idle, it's time to replace the TPS. Now, something that can throw the TPS off is if your idle isn't adjusted properly. Most folks adjust the idle stop screw to up the idle, which opens the throttle a bit more and also changes the TPS value. This can throw off the computer, which presumes the throttle is closed at idle. Try adjusting the idle according to these instructions and see if that helps your rough idle. You may have to re-adjust the idle after fixing the other issues.

http://www.stangnet.com/mustang-for...laggin-spuuter-problems-help.html#post8237206

I take no credit for the idle adjustment instructions, I just re-posted them after removing the TPS adjustment procedure.