I really need some ideas here.
My 89 started running extremely rich. It is giving me no codes out of the computer.
Everything I look at checks out fine. I pulled out all 8 plugs and they are very black.
The scanner picks up nothing and the fuel pressure regulator is working fine.
(If I disconnect a sensor the computer spits out the proper code so I am pretty sure it is reporting accurately. The scanner is a brand new Snap On Modis)
A couple of weeks ago I replaced the diaphragm in the fuel pressure regulator (it was leaking) and the coolant temp sensor. (It was picked up by my scanner) They seem to be working fine. This problem started about 2 weeks later.
This car is a daily driver and has about 95000 miles on her. It is stock except for a stainless exhaust and a K&N air filter.
Has anyone out there experienced anything similar?
I don’t want to buy a new ECM and find out that it is not the problem and after hours of looking at this I am running out of ideas.
Thanks for you time.

Glen.


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Had a similiar problem on my 92 which caused it to dramatically fail an emissions test. The ECM actually would throw a lean condition code(causing the computer to richen the mixture) which led me to replacing both O2 sensors. Once replaced, everything returned to normal (including much better gas mileage). The O2 sensors are pretty inexpensive but are a pain to replace if they have never been replaced.

-John

 

One thing you might try is unplug your MAF and see if the performace increases. By unplugging Mass Air Flow, you are putting it in a back up mode with preprogrammed responses to throttle position. What grams per second air flow are you getting @ idle? You can also test your O2 to see if it will lean out by unplugging vacuum hose to brake booster and see if O2 voltage goes lean , > .2 v, which indicate the O2 is responding to engine conditions. Get back on your readings. [8D]

 

My friend on another forum is having a rich problem. He had 24 lb injectors in his car from Accel. He hasnt figured out if that was his problem yet. He is selling the Accels and is having is stock injectors rebuilt right now. Ill ask him once he gets it worked out. Maybe a injector is leaking....Are your cats glowing?

 

Thanks for the replys. I replaced the ECM and it is running OK again.