The Oxygen Sensor "Puzzler"

[nascar24jd]

Re: The Oxygen Sensor "Puzzler"

Did you check too see if the light bulb for the SES is good?

Yes, the light is good. It comes on when I turn the key on and goes out after the engine is running.

It also loves to come on after a long highway run, which I have been told is a common EGR issue with the 3.4 EGR system.

It appears that for whatever reason the PCM is stuck in open loop.

[bigbrian442]

Re: The Oxygen Sensor "Puzzler"

You need to plug in a scanner that can access the data stream to verify what code it's setting on highway cruise and that's it's not entering closed loop.

[nascar24jd]

Re: The Oxygen Sensor "Puzzler"

Update...

After running out of ideas, I disconnected the car battery overnight to reset the computer. After driving the car the next day I scanned it and this time the SES light did flash and it indicated no codes stored.

I drove the car for a few days and filled the tank. The average was 15.5mpg local driving. Not bad.

Today I had to take a quick run up North, 80 miles round trip. I filled the car before and after the trip to get a true highway mileage calculation. The mpg was 18.8 after the highway run. Very good for this car.

Overall I am very pleased with the results. Keep in mind that I run with the a/c on all the time and I do not baby this car.

After getting home I scanned the car again and the SES light flashed indicating no codes stored.

:banana: :rock:

[tkoforpresident]

Re: The Oxygen Sensor "Puzzler"

glad to hear.

[nascar24jd]

Re: The Oxygen Sensor "Puzzler"

The person that can answer these questions is clearly the smartest person on our fine board...

I will call it a tie between bigbrian442 and tkoforpresident. Thanks guys.

[auto666]

Re: The Oxygen Sensor "Puzzler"

check your fuel pressure low pressure will kill your milage
i have a 94 3.4 m5 i had an issue with the crank sensor it wasnt reading but it also wasnt throwing any code i just noticed it one day when i was playing with the genisis in between changing the crank sensor and fixing my exhaust leak my performance and fuel milage became much more consistint.
i live in a small small small town, car only gets fully warmed up a couple times a week now and im still at 21mpg and im always in it atleast to the city wide speed limit of 35(yeah gotta love small towns.)

[tkoforpresident]

Re: The Oxygen Sensor "Puzzler"

I will call it a tie between bigbrian442 and tkoforpresident. Thanks guys.

:banana::banana::banana:

[nascar24jd]

Re: The Oxygen Sensor "Puzzler"

:banana::banana::banana:

Yes my friend. I am just glad that I can spend a little less on fuel.