Enriching circuit

1990 SC 5 spd

Registered User
Is there an enrich circuit? The car won't idle, or run under 1500 rpm without working the throttle. It spits and hesitates. The exhaust is black. It will start but as it warms the fuel stays too rich. Any ideas?
 
At boost and under WOT the computer is programmed to supply a generous quantity of fuel, to prevent ping. If the oxygen sensors are bad the car will run rich. It could also be very dirty fuel injectors running rich.
 
Yah check the O2 sensors, Know of a guy that had the same problem, all he did was remove the O2 sensors and cleaned them, depending on the milage/age of them, may be worth replacing..

Also check the FPR the hose may of come off or something... that combined with some what fouled O2 sensors....
 
I sealed the Supercharger adapter and intake adaper with silicone. Have heard not to use silicone spray on things like the throttle body shaft as it may seep in an contaminate the O2 sensors. I wonder if fumes could. It does seem like O2s. They are new and it drove for about 20 miles before the problem. Would a muffed up EGR system cause richness?
 
AsScLoWn said:
check fuel pressure and check codes, you need a fuel pressure tester and code reader

I have a hard code 82. Air diverter valve or supercharger bypass circuit. There is no air diverter valve and the bypass valve opens when I apply vacuum. Does your bypass valve open when your car is running? Mine is open and as I rev the motor is closes, there are no electrical hookups.
 
91 XR7 said:
Yah check the O2 sensors, Know of a guy that had the same problem, all he did was remove the O2 sensors and cleaned them, depending on the milage/age of them, may be worth replacing..

Also check the FPR the hose may of come off or something... that combined with some what fouled O2 sensors....

Will throttle body cleaner work, whats inside the slits? I've got 1 out its dusty with black soot.
 
Hmmm. I would verify the fuel pressure regulator is intact and isn't dumping fuel down the vacume line. If the fpr fails it can often dump fuel down the signal line which dumps right into the intake, thus a rich mixture. Fuel usage should also be through the roof.

Black smoke is WAY too much fuel. I would think the oxy sensor would have to fail bad enough to throw a code if the car blindly throws that kind of pulse width at the injectors. Instead I would expect it to "guess" using internal tables and thus run rich, but I wouldn't expect black smoke rich.

Did you try pulling any codes?

You could test the OXY sensor theory by taking the Oxygen sensor out of the loop. Disconnect it, you should get a check engine code, but no black smoke. Car will use tables based on engine temp, throttle position, and MAF readings.

Black smoke quantities of fuel sound like failed pressure regulator, and or bad injector. If it wasn't so difficult I'd say pull the plugs and see if you can isolate the issue to a particular cylinder.

Using Garage Logic.
 
to clean them, use a propane torch to burn off the carbon, but make shure you don't let it get red <glowing> hot..

it worked for me many a time, Also with the other guy, his car never threw a code, it just did it.. and after cleaning the O2 Sensors, hasn't done it since <that i know of>
 
I've just rebuilt the engine and suspension. Got to drive it 18.7 miles. After driving the van for 26 months, I'd forgotten how nice these cars are and why I continue on. I appreciate the tips. I've got to get a fuel pressure guage, and propane torch.
 
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