when i go to my weekly strip cruising up in Worcester MA, the car always hits 220 and after a while of running at that temp i begin to smell gas...most likely the car is running rich. why is this happening or what could it be? anything bad?

 

Specs on the car help. Most likely it's a bad or lazy O2 sensor. And they don't always throw a code. Went through the same thing with my 89, was smelling gas after closed loop. Replaced the O2 and it's been fine. After about 25-30k they get slow in responding. How's the gas mileage, notice any change lately.

 

91 Z28 350 TPI, gas mileage seems no different, this only happens during heavy traffic where its stop and go for about 60ft every red light and the car stays at 220 degrees if not a little higher. i also got rid of my cats if that affects anything....

 

what o2 sensors are good to get, bosch? any others?i have an 84 lg4 i think its the one wire sensor, can it be changed to a better kind, heated? three wire? i dont know what they are/do?

thanks for any explanation

 

I use the AC Delco replacements. Some aftermarkets don't come with the plug they give you a butt connector and you splice the wire. The heated ones can be used, you need additional wiring and they cost about double. That's up to you.

 

If you have access to a scan tool I would check to see what the O2 sensor is doing first, it should be changing back and forth between high voltage and low voltage as well as rich and lean somewhat rapidly . I'd also check to see if it was going into closed loop or staying in open loop. After you change out the O2 I'd recheck to verify that the problem is fixed.

The O2 sensor measures the amount of unburned Hydro-Carbons in the exhaust system. It feeds this info back to the ECM/PCM which inturn uses the data to determine fuel useage. I'm really not sure why they're called O2 Sensors, its misleading. The O2 sensor is designed to operate at a very high temp. If your running headers it wont get hot enough to work correctly. Therefore a heated sensor is required.

Here is a link that tells how to do the conversion

http://sethirdgen.org/HO2S.htm


Bill

 

You can do the same thing by placing the ECM in the field service mode. Jump the ALDL connector when it's running. If it's in closed loop the SES light flashes once per/sec. Lean the lamp will stay off for most of the one sec cycle, if it's rich it will stay lit most of the one sec cycle. Don't start the car with ALDL jumped, only insert the jumper after it's running.

 

This is something I hadn't heard. I've been to training sessions on GM driveability, and nothing has ever been stated about this. I know you can pull codes using a special key, but this is new to me. I'm not trying to doubt what your saying. I guess since we're tech's, they expect us to use scan tools. Maybe you could do a technical article and explain exactly how to go about the field service mode.

 

How much are the o2 senser.

:rockon: :rockon:

 

i went to orileys last night for a new o2 sensor, i got a stock bosch sensor it was 24.99$
i asked about the three wire sensor and i gave a acdelco part # and he gave me a borg warner part, he said it would have to be ordered, but he gave a price like 62$ or so, i think he had a different brand prolly bosch for just a bit cheaper, in the 50's$
thats all i found, i want the ac delco three wire sensor, where to i go the dealer? i can get a good bit of ac delco at orileys for my tune ups...