Hey guys, I haven't been on the forums in a while but it's good to see it's going strong! Anyway, here's a problem my 91 GT devoloped yesterday.
First the car:
It had parked for about 3 years until about 3 weeks ago. I just got it back on the road and have ran about 3 or 4 tanks of gas through it with no problems at all. As I said, it's a 91 GT AOD. Stock motor, headers, h-pipe, catback. It has an onld ball bearing drive paxton supercharger (SN2000 I think) and an aftermarket MAF, don't remember the brand off hand but it's calibrated for the stock injectors and suck thru supercharger setup, and a 255 (I think) fuel pump. Sorry for so many "I thinks", its been about 6 or 7 years since I really worked on the stang so my memory is fuzzy.
Now the problem:
The car had been running like a champ. I filled the car up saturday from about empty and drove home, about 20 miles. Yesterday (sunday) evening my girlfriend and I drove about 15 miles to eat and then I was going to take her home. Almost as soon as we started toward her house the car started running slugish. At first it wasn't too bad, just seemed underpowered. Within about 15 miles it had a noticable miss above 3500rpm at 3/4 throttle or more. I could put the car in first from a stop and slowly add throttle and it would build to about 4500rpm then start cutting out and not get any higher. While I was driving (about 40mph) I could go to WOT and she would just sputter and miss. I could hear popping from the exhaust and smelled rich.
I dropped the girlfriend off at her house and started home (about 40 miles since the first problems) and the problem just got worse, more noticable above 3500rmp and now sluggish below 3500rpm. At one point she doesn't even have enough power to move, almost stops in the road. I pull over, look under the hood, start her back up and shes moving again, still very sluggish.
This morn I start her up, and she runs very rough at idle, doesn't want to run at all. I pulled a couple spark plugs (#3 and #6) and they were light tan and very clean. So then I decide to try unplugging the MAF, and she starts up and idles great. Revs up to redline smooth, seems to be good. Plug the MAF back in and she idles rough and dies. Unplug it again and she runs fine. I figured it was a bad MAF and the EEC swithced to fuel tables when I unplugged it, problem figured out... not! I give her a little test drive (being very gentle w/o the MAF plugged in) and she still has a miss above 1/2 throttle. By time I had driven 20 miles round trip she was back to being very sluggish above 3000rpm, would not take anything above 1/2 throttle, and did not want to idle. I could pull out slowly as long as I was very slow with the throttle.
The final leg of the test drive is a 1/4 block long fairly steep hill to my house. About half way up the hill the car loses all power. She's still running a very low and rough idle but will not move up the hill. I have to shif to neutral and slowly give her some throttle to get the rpms up and smooth then drop her into drive and she just does make the hill. As I pull into my driveway (also a little steep) same thing. Not enough power to move. It takes three 2500rpm neutral drops to get 10 feet up the driveway. Then as I level out to the parking spot, she dies and will not start back up.
A recap of what I tried/checked:
Cleaned dizzy cap and rotor contacts
Checked all plug wires
Pulled #3 and #6 plugs (clean and light tan)
Topped off fuel (about 4 gallons)
Checked Fuel Pressure while parked and revving to about 5000rmp (stayed about 30psi)
Listened to fuel pump, sounded ok/normal
Visual inspection of all wires, plugs, sensors
Unplugged MAF, helped at idle at first but problem returned within a couple miles.
I hope that is enough info, sorry for such a long post. If you have any suggestions please let me know. I at least need a place to start. I'm kinda leaning towards fuel problem, filter? pickup? injector? anyway, please help if ya can! Thanks...
James
First the car:
It had parked for about 3 years until about 3 weeks ago. I just got it back on the road and have ran about 3 or 4 tanks of gas through it with no problems at all. As I said, it's a 91 GT AOD. Stock motor, headers, h-pipe, catback. It has an onld ball bearing drive paxton supercharger (SN2000 I think) and an aftermarket MAF, don't remember the brand off hand but it's calibrated for the stock injectors and suck thru supercharger setup, and a 255 (I think) fuel pump. Sorry for so many "I thinks", its been about 6 or 7 years since I really worked on the stang so my memory is fuzzy.
Now the problem:
The car had been running like a champ. I filled the car up saturday from about empty and drove home, about 20 miles. Yesterday (sunday) evening my girlfriend and I drove about 15 miles to eat and then I was going to take her home. Almost as soon as we started toward her house the car started running slugish. At first it wasn't too bad, just seemed underpowered. Within about 15 miles it had a noticable miss above 3500rpm at 3/4 throttle or more. I could put the car in first from a stop and slowly add throttle and it would build to about 4500rpm then start cutting out and not get any higher. While I was driving (about 40mph) I could go to WOT and she would just sputter and miss. I could hear popping from the exhaust and smelled rich.
I dropped the girlfriend off at her house and started home (about 40 miles since the first problems) and the problem just got worse, more noticable above 3500rmp and now sluggish below 3500rpm. At one point she doesn't even have enough power to move, almost stops in the road. I pull over, look under the hood, start her back up and shes moving again, still very sluggish.
This morn I start her up, and she runs very rough at idle, doesn't want to run at all. I pulled a couple spark plugs (#3 and #6) and they were light tan and very clean. So then I decide to try unplugging the MAF, and she starts up and idles great. Revs up to redline smooth, seems to be good. Plug the MAF back in and she idles rough and dies. Unplug it again and she runs fine. I figured it was a bad MAF and the EEC swithced to fuel tables when I unplugged it, problem figured out... not! I give her a little test drive (being very gentle w/o the MAF plugged in) and she still has a miss above 1/2 throttle. By time I had driven 20 miles round trip she was back to being very sluggish above 3000rpm, would not take anything above 1/2 throttle, and did not want to idle. I could pull out slowly as long as I was very slow with the throttle.
The final leg of the test drive is a 1/4 block long fairly steep hill to my house. About half way up the hill the car loses all power. She's still running a very low and rough idle but will not move up the hill. I have to shif to neutral and slowly give her some throttle to get the rpms up and smooth then drop her into drive and she just does make the hill. As I pull into my driveway (also a little steep) same thing. Not enough power to move. It takes three 2500rpm neutral drops to get 10 feet up the driveway. Then as I level out to the parking spot, she dies and will not start back up.
A recap of what I tried/checked:
Cleaned dizzy cap and rotor contacts
Checked all plug wires
Pulled #3 and #6 plugs (clean and light tan)
Topped off fuel (about 4 gallons)
Checked Fuel Pressure while parked and revving to about 5000rmp (stayed about 30psi)
Listened to fuel pump, sounded ok/normal
Visual inspection of all wires, plugs, sensors
Unplugged MAF, helped at idle at first but problem returned within a couple miles.
I hope that is enough info, sorry for such a long post. If you have any suggestions please let me know. I at least need a place to start. I'm kinda leaning towards fuel problem, filter? pickup? injector? anyway, please help if ya can! Thanks...
James