surging problem finally fixed (long)

shelby2 · 09-08-2001, 01:28 AM

i have finally found out why my mustang won't idle smoothly and surges. i had some bad wiring in my harness that goes to the tps sensor. what i did is i checked the voltage on the sensor and wiggled the wires to see if there was any change. at some points the voltage went from .95 to over 5. so what i did is i cut the wires coming out of the computer harness plug-in and the wires on an old tps sensor and ran new wires in between the cuts. set the voltage to .95 once again before starting it and trying it out. for the first time since i put on the fuel injection it actually ran smooth by itself, without being above 1300 rpm. i have it idling at 850 now, and with a 292 duration cam, it sounds mean. so monday i am going to go buy a new main and injector harness from ford and replace them all. it's amazing how one little bad connector can make your car run like crap.

i just thought that i would share this with everyone because i know a lot of you also have idle problems and this could be one place to start. i also have a friend who is a mechanic and he told me that once you disconnect a reconnect harness plugs 3 or 4 times, they don't fit like they should and could cause improper voltage readings for the sensors.

now onto the bodywork

------------------
shawn hill
1967 ford mustang coupe, red w/white stripes, hood scoop, front and rear spoiler, sefi and c4, trickflow intake, 70mm mac tb/egr, billet fpr, 24# inj, c&l maf, heavy duty c4 w/transgo shiftkit, msd 6a box w/tfi blaster coil, flowtech longtubes w/turbo mufflers, t-rex inline pump, ported and polished E7TE heads w/1.94,1.60 valves, lunati 292 cam, harland sharp 1.6 rollers, conventional 8" with 2.79 gears (soon will be gone)

PKRWUD · 09-08-2001, 12:39 PM

That, my friend, is why doing diagnostic work over the internet can be so difficult. Congratulations on figuring it out! Keep up the good work!

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

09-08-2001, 01:28 AM	#1
shelby2 Registered Member Join Date: Nov 1999 Location: O Fallon, IL Posts: 87	surging problem finally fixed (long) i have finally found out why my mustang won't idle smoothly and surges. i had some bad wiring in my harness that goes to the tps sensor. what i did is i checked the voltage on the sensor and wiggled the wires to see if there was any change. at some points the voltage went from .95 to over 5. so what i did is i cut the wires coming out of the computer harness plug-in and the wires on an old tps sensor and ran new wires in between the cuts. set the voltage to .95 once again before starting it and trying it out. for the first time since i put on the fuel injection it actually ran smooth by itself, without being above 1300 rpm. i have it idling at 850 now, and with a 292 duration cam, it sounds mean. so monday i am going to go buy a new main and injector harness from ford and replace them all. it's amazing how one little bad connector can make your car run like crap. i just thought that i would share this with everyone because i know a lot of you also have idle problems and this could be one place to start. i also have a friend who is a mechanic and he told me that once you disconnect a reconnect harness plugs 3 or 4 times, they don't fit like they should and could cause improper voltage readings for the sensors. now onto the bodywork ------------------ shawn hill 1967 ford mustang coupe, red w/white stripes, hood scoop, front and rear spoiler, sefi and c4, trickflow intake, 70mm mac tb/egr, billet fpr, 24# inj, c&l maf, heavy duty c4 w/transgo shiftkit, msd 6a box w/tfi blaster coil, flowtech longtubes w/turbo mufflers, t-rex inline pump, ported and polished E7TE heads w/1.94,1.60 valves, lunati 292 cam, harland sharp 1.6 rollers, conventional 8" with 2.79 gears (soon will be gone)

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09-08-2001, 12:39 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	That, my friend, is why doing diagnostic work over the internet can be so difficult. Congratulations on figuring it out! Keep up the good work! Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!