I have a 1988 GMC 3500 with a 454 tbi the problem im having is small but very annoying. I'm getting the 44 code 02 senses lean fuel which is probley right cause sometimes when its cold it has a little knock then goes away. I have done mods to the truck, smog and a/c delete, headers, 3" exhaust with flowmasters and a carb style air cleaner. The truck starts up great and idles fine, if you put it to the floor it has no hesitation what so ever. Sometimes going done the road mostly when its cold taking off at normal pedal it will seem like it has dead spots in the throttle like its cutting out and every once in a while it will throw the 44 code and run like crap down the road and the light will either shut off and start running fine again or i'll just shut it off and restart it and will run fine, no matter what it seems even when warm it will cut out a little on easy take off if i floor it though its perfect and also once in a great while the volts will go from around 15 and drop to 9 and start fluctuating kinda weird ive checked the connections and everything seems to be fine any ideas?

 

If its running lean, check for vacum leaks around the carb and intake.

 

Well got rid of the 44 code I just ended up clearing the code then disconnecting the map sensor and drove it 10 miles or so then rechecked what codes were stored and the 44 wasnt so i knew right there the map sensor was senseing higher vacuum creating a lean fuel mixture so replaced that and now im getting code 13 which my 02 sensor is new and the ses light goes on and off so im thinking its either a bad connection or having headers, 3" exhaust with no h-pipe might be the problem if not the ecm is just screwed up.

 

OHHHHH! That may be why my friend. The headers. Unless you are getting really poor mileage, I wouldn't worry bout it.

 

i dont know whats wrong now that 13 code is making it run like crap everytime it comes on the truck just hesitates and stumbles its running like **** and i want to just beat it with a sledge hammer!

 

Just a thought, but also check or replace the throttle position sensor. http://www.freeautomechanic.com/diag...blecodes5.html