New;

Mass air flow sensor, coolant temp sensor(hard to reach one), oxygen sensor, throttle position sensor, fuel pressure regulator, all fuses cleaned, new air filter, plugs, wires, cap and rotor. All injectors work fine and don't leak, cold start injector working ok also not leaks, idle air control functioning properly, no vacuum leaks. Car runs rich, all plugs are black, "check engine" light is on, I believe code 3-1-2, computer compensating for extremely rich or extremely lean mixture. I reset the computer numerous times and after each part replacement, takes about 5 to 6 miles of driving to turn on "check engine" light.

Took out computer, found a grey looking piece on computer board burnt out, replaced with same piece out of a Renault Aliance computer. Still no luck. Now locating a used computer to troubleshoot with. Any ideas. After computer changeout is wiring harness replacement.

Car is 1989 with approx 100k on it.

Frustrated but not giving up,

I see that you have replaced about everything but the computer.

I have only one suggestion that follows the thought that the wiring harness could be a problem.

Check the connections on the computer again but back probe the one from the computers coolant sensor, not he gauge one. You said you change the hard one which probably was the computer one.

When you back probe the sensor at the computer connection, (engine off and connector off) with the engine cold, it should read about 2000 ohms. Then after the engine is warm it should be less. About 100 ohms.

If the computer is being told 2000 ohms, or even higher if there is a bad or no connection, the engine will run richer.

Just a thought, maybe you have been there and done that?

Neil,

I think I've solved my problem........Intake Air Control......inside where hoses connect was extremely gunked up,cleaned

this up with gumout throttle cleaner & sprayed real good with WD40.I also broke the factory seal (8 tabs)and cleaned the brushes and magnets and magnets with emerycloth.I just figured I had nothing to lose. I wondered about this yesterday when the key was turned on

without engine running,this thing would just buzz away. Anyways after this it started right up.....no black smoke!!! The idle

droped back to 750 rpm's and no surge.Was also having problems running ruff between 45-50mph......Gone!!! Will also hold a

steady speed without sputtering and surgeing.Gas mileage has improved greatly, as we were only getting about 10 feet to the

gallon.I also changed the oil & filter now that this problem has cleared up.....oil smelled like gas & thinned out after only

a 150 miles.I was trouble shooting without the help of scan tool,just a Haynes auto manual and a lawn chair to plop my

rearend in to sit and wonder.......Good Luck!

Have you looked into a possible intake Manifold Air Pressure (MAP) Sensor fault? Clogged Cat? Intake leak between AMM and throttle body?

Neil,

It seems were suffering the same problems and have replaced many of the same things.I don't have an answer just a question

how do you reset the computer? I just swapped engines last weekend,88740GLE 127k blown motor (kids) to 87 w/102k.

This problem is driving me nuts.

The computer reset is very simple, just disconnect the battery for 10 15 seconds. I tried disconnecting it for 2 or 3 seconds and the computer remembered the codes. If you really want to be sure, disconnect it for a minute or so and all of the memory should be wiped out. It may run a little rough for a minute or two until the computer relearns all the values.

Is your check engine light coming on?

Did you scan the codes?

If so, what is coming up?

E-mail correction neil.gyuris@am.apbiotech.com