I recently bought this 91 gt, and since buying it, I have given it a tune up and put a complete exhaust system on it, including the converters. I had to buy one new oxygen sensor, since all the threads stripped out of one when taking it out of the old exhaust. The car had no power at first, and the cats were making that rattling sound so I figured they might be clogged. The check engine light always came on when I first bought it. Now, after doing all this stuff, the car runs great, power seems ok. I am getting 17-18 mpg averaging 65-75 on the highway. The problem is how do I reset the check enging light? I had the battery disconnected when I did the starter. Is it possible I still have a problem with something?</P>

 

it more than likely is there , leaving the batt off for a good amount of time should clear kam , get a code puller from a parts store , autozone for fords , you can also do it via a multi meter , pull codes then go from there dont be guessing , plus it will erase them for you too

 

put the other 02 sensor on

 

if I get a code scanner, will it tell me if the other 02 sensor is bad? I hate to run out and spend another $40-50 on one of those things if that is not the problem. Also, what do stock 5.0 mustangs usually get for mileage. My girl used to have an 88 gt convertible, and I think I remember that getting in the 20mpg range. Does this sound right?

 

YES.....on both

 

yah you should be gettin around 24mpg in town and better on the highway......on the highway with 2.73's i get 30mpg...cant compain about that,,

 

Deffenlty go with new O2 sensors.

 

If an 02 sensor is bad would that hurt the mileage? Can it cause the converters to clog?

 

yes it will hurt mileage
gorbs..*L* maybe in a 4 banger...24-25 is about it and 18-20 in the city if you don't get on it<edited><editID>vfast</editID><editDate>37995.7239814815</editDate></edited>

 

I have the same problem..the check engine light won't go away after I replaced both O2 sensors and EGR valve. If I leave the battery disconnected will this go away?