Engine Economy

[deerejohn606]

Try not to laugh, My "92 xploder with 223,000 started to run rich about a month ago, with about a 33% reduction in mileage. I ran the engine codes and pulled 1)02sensor faulty 2) egr valve faulty 3) rich mixture. Thinking I could have missed something with my 5 year old $50. scan tool, I went to see the the local fuel & electronics guru. After 2 1/2 hours@$ 45. per hr, with his $25,000 analizer, he told me the same thing my scan tool did. However he did say my engine doesn't have an egr valve. Also he told me that it seems to be locked into a cold running mode even though the computer sees 193 degrees. At the time the whole thing started a noise developed in the rear of the engine that sounds like a faint windshield washer pump cycling on and off intermittantly. You can only hear it from the front seats, and it is too faint to hear under the hood. My first thought was vacuum, but I don't find anything. I did change the O2 sensor with an OEM replacement. And the Guru cleaned the MAF sensor, and checked fuel pressures. Any other suggestions???

 

[mdrut]

Did he check to see if the fuel was returning to the tank?
Sounds like the fuel pressure regulator is "STUCK" in the closed position..
SYMPTOMS
poor mileage
poor acceleration
smell of rich mixture from exhast
smokes when under heavy acceleration

Codes will point to rich mixture, O2 problem.

 

[Opera House]

Maybe it's the vacuum line

running to the fuel pressure regulator which is off or has a hole in it. That would cause it to run rich or the diaphragm is leaking gas into the manifold. Frankly, I wouldn't touch this car till you put a new FPR in. I had problems on my 92 that drove me nuts. After that I don't trust a FPR with a lot of miles on it. If you change it, you must disconnect the battery to reset the computer.

 

[Apten]

my guess, ECT sensor. If it doesn't see the engine reach a certain temperature, it will run on a "base fuel table" that will command the EEC to run WAY rich.

also, check your thermostat.

 

[deerejohn606]

Many thanks for the suggestions, I'll concentrate my efforts in those directions!