Hello, I've spent the last hour or so, once again doing the search thing. my story: My 97 Z' s Opti was replaced this last summer--the winter before that in cold wet weather it would be real hard to start, chugg,buck and the flashing ses would come on--run ok after you got it going. About 2 weeks after opti replacement, the ses light for a bad driver side cat came on-(replaced the post o2 sensor that side)-it still stays on a few days-goes out and repeats later on--I thought i had my flashing ses fixed until it got cold and wet again--same story again--with the cat problem new this year--Seems like I read if there was gas in the vacuum line from the fpr to the manifold, it could be bad--I took that plastic line off-no liquid came out, but i could smell gas AS dumb as that may sound--I was thinking maybe no gas smell or liquid gas was suppose to be there and it was only a vacuum line to the manifold--car does burn rich even in the summer,( hate to pull into a drive thru bank teller window),but cranks up good until it got wet and cold --Thanks Dwayne

 

The low cat efficiency code isn't affecting anything, but you should have checked to see whether it was due to a faulty O2 sensor or a dead cat, before you replaced the sensor. The fact that the sensor didn't fix the problem would seem to indicate it may be the cat.

Wet weather means moisture/condensation on the igntion wiring. Have you checked the wiring by running the engine in a dark area, and lightly spraying a mist of water on the wires and other ignition components. Might produce some sparking, indicating weak insulation, corroded terminals, etc.

Also need to check the coolant temp sensor. May not be giving the PCM the correct info in cold weather.

Need to run down the cause for running rich. Misfires will make it run rich, as will a fualty coolant temp sensor, excessive fuel pressure, exhaust leaks before the O2 sensors and faulty O2 sensors/wiring.

Have you ever done a data log, and looked at the long term fuel corrections? That may point out the source of the excessive rich condition.

 

Thanks for the reply, I dont have anything to do a data log with,but i will spray a light mist over my wires(away from the opti) to check for sparks. Dont know why I got a bad fpr in my head--Is it suppose to have a gas smell in the tube from the fpr to the right side manifold?? Like in my first post i thought maybe it was only a vacuum line with no gas smell in it Thanks again Dwayne

 

The smell may indicate a leak. Run the engine without the vacuum line connected to the FPR, and look for fuel leaking out of the nipple on the regulator. Need a mirror to do that. You could also check your fuel pressure with a gauge. A leaking diaphragm is not going to provide the correct fuel pressure.