With oxygen sensor harness plugged in, bucks sputters and back fires.

[cardudeusa]

I just replaced the motor in my 87 GT a few weeks ago. It runs great, when the oxygen sensor harness is unplugged. As soon as I plug it in it bucks and back fires and doesn't want to go. The oxygen sensors did sit out side in the weather for about 2 weeks still pluged in the old H pipe. Do you think the oxygen sensors are bad or is it something else???

 

[Michael Yount]

Pull the codes first...

 

[bradranger]

o2 sensor

more likely its the o2 sensor or sensors, I would replace both. But I would pull the codes just to make sure.

 

[jrichker]

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

 

[cardudeusa]

Ok, looks like I will be pulling the codes Sunday.

 

[cardudeusa]

Well I decided to say screw it and not check the codes and just buy some new O2 sensors and put them in. Fixed my problem. Car runs great now, just needs body work and rims, and I'll be happy.

 

[bradranger]

o2 sensor

Great, glad to hear that you fixed the problem! I had the same problem about a month ago, and I replaced my o2's and then it ran fine.

 

[cardudeusa]

Yep, I'm surprised it ran that bad just off those stinkin sensors!

 

[Michael Yount]

Mine were completely unplugged for 6 years/18,000 miles; you couldn't tell that anything wasn't completely as it should be. Perhaps a screwed up signal causes more problems than no signal at all.

 

[cardudeusa]

Mine were completely unplugged for 6 years/18,000 miles; you couldn't tell that anything wasn't completely as it should be. Perhaps a screwed up signal causes more problems than no signal at all.

Yeah, it ran fine without them in, but I didn't want to get bad gas mileage.