2002 Mustang GT 5spd hesitation issues

trlps_

New Member
Feb 25, 2020
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Hello, so i recently just changed my spark plugs in my 02 mustang gt 5speed, which from that changed a sputtering problem that i had for a while, after changing the plugs with new ones car ran great, changed them out about a day ago. Took the wife to work earlier today and car ran fine as well, WOT felt great and the car ran good per usual but a few hours ago i go to leave and i did notice a idle problem. the idle would dip down and nearly die but would catch back up and go back to the normal 750-800rpm range that it idles at. Tried driving around the block to see if it was an idle issue or something else, but going around the block it would sputter and nearly shut off despite giving plenty of gas, car didnt sound healthy at all but once it would get past about 2-2500 rpms it sounded like it would catch back and sound back to normal and healthy again. Just took it back apart to check the IAC and throttle body as well as the plugs to make sure everything was okay, everything checked out aside from some carbon build up in the IAC and throttle body. Put everything back together and drove it around the block again, hesitation and sputtering was not as bad but it was there. Drove it to the highway to see how it would act, giving it throttle it would go but it also sounded like it was hesitating more than usual. Easing into throttle it sounded fine but as far as WOT or even more than easing into it, it would just sound and feel terrible. Anybody have any ideas? I'm thinking maybe it could be the fuel filter or pump but not 100% sure before i go and start taking it apart and it being something else. Any suggestions would help, thanks in advance!
 
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PSKSAM2

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Feb 13, 2002
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My fuel pump went on my 02 last year. Started with some hesitation, rough running, then trouble starting. I dropped the tank and replaced it myself.

I was also thinking coil packs, but I'd think you'd have a misfire and throw a code. I had that too, if I was going up a hill in a high gear, it started to notice a miss. Did plugs and coil packs and it resolved.
 
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trlps_

New Member
Feb 25, 2020
26
0
1
22
Houston
My fuel pump went on my 02 last year. Started with some hesitation, rough running, then trouble starting. I dropped the tank and replaced it myself.

I was also thinking coil packs, but I'd think you'd have a misfire and throw a code. I had that too, if I was going up a hill in a high gear, it started to notice a miss. Did plugs and coil packs and it resolved.
someway somehow i didnt plug back in the injector to cylinder 4, plugged it back in and solved my issue. Still leaning towards fuel pump & filter just due to a little hesitation that its still giving me.
 

wmburns

SN Certified Technician
Aug 14, 2009
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Anybody have any ideas? I'm thinking maybe it could be the fuel filter or pump but not 100% sure before i go and start taking it apart and it being something else. Any suggestions would help, thanks in advance!
Why guess? Test!

Use an ODB2 scanner to data log data PID's such as:
  • RPM's
  • MAF flow
  • Short term fuel trims
  • long term fuel trims
  • fuel pressure
  • ECT
  • IAT
Also look at the ODB2 mode6 misfire data while driving.

IF you do have a fuel delivery problem this will show up in the STFT's and LTFT's as well as the fuel pressure.

The $30 cost of the ODB2 adapter could pay for itself with the first good part not changed.

ForScan ODB2 scanner w ELM327 USB