Hey everyone,
i have a 1988 formula with a 355 TPI, and lately my engine light has been commin on just out of nowhere, then it goes off like 2 min later..i scanned it with 2 different types of computers, and each one says, o2 sensor failure, or incomplete o2 circuit, i replaced the o2 sensor and still getting the same codes.. which is a 13 if anyone is wondering... but what should i check next?? im so stumped, my car is acting like it has PMS, and its pissin me off, i wanna see if i could fix it so i dont have to buy all the carb set up. haha....but any help would be appreciated so much, thanks

drew

 

The first thing I would check is the connector from the O2 sensor wire to the wiring harness, clean the metal on the wiring harness end with some fine sandpaper. If that doesn't solve the problem I would follow the wire looking for damage.

 

Is the light still actively coming on while the car is running? If not, be sure you disconnect the battery for 30-60 seconds to clear the codes.

If you can scan it, start the car, let it warm up for a few minutes (5 or so), and drive it around (have a friend do it) while watching the scanner (watching the 02 and/or the O2 cross counts). During normal driving under normal loads, the cross counts should be consistently incrementing and you should see the O2 fluctuate above and below 550mv or so.

If this isn't happening, your car won't go into closed loop. You can tell if your car is in closed loop on your scanner as well. If this is the case, check to make sure the O2 is properly connected and that you have the correct one for the car.

Did you re-seal your intake recently? Did you use sensor-safe sealant? Any other silicone around the engine compartment (even if you dress it up with silicone-based tire-shine, cleaner, etc)? If so, this will destroy an O2 instantly.

 

yea the light comes on when im driving for about 10-15 min ya know just enough to warm it up, then the light will come on for about 2-5min and then go off for a couple hours. the o2 sensor is brand new, just put it in like a week ago, and i double make sured it was the right one. ill trace the wire, and drive around with the computer hooked, see what happens, anything else it might be?

drew

 

Try adjusting the Throttle position sensor, if it is incorrectly set, it will often give you a malfunction code for the O2 sensor.

The Trickster!!!!!!!!!!!!

 

thats good i had that tested too

 

Hello Drew,

I have just e-mailed you a troubleshooting chart for the O2 sensor. Hope it helps you!!!!!!!

The Trickster!!!!!!!!!!!!!

 

thanks for all the help, it was 2 ground wires that disconnected from teh back of the engine, a pain to get to but i got it, runs like a champ now, thanks again..

drew