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5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

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Old 07-20-2006, 04:03 AM   #1
95DkGrnGt
 
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Default low rough idle

Hi everyone this is my first post. I didn't find any threads that helped me with my problem. hope someone here might have some insight.
The other day i went to start my car and the fuel pump was dead(over 160K on the stocker) so i ordered a 155 LPH from SUMMIT. I bought their SUMMIT pump(made by walbro) and installed it. my car starts faster and has smoother acceleration but i now have a very low stumbling idle. nothing else was done to the car at the time. For along time i've had an idle issue running A/C at an idle to the point of dying and figure the IAC is the culprit, but i've never had an unloaded idle problem. Could it possibly be a pressure problem and i need an adjustable regulator? OK thats all i can think of right now. Thanks for any help.
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Old 07-20-2006, 04:43 AM   #2
FiveLiterRiceEater
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Default RE: low rough idle

pressure is probably fine. it sounds like you might have a dirty or plugged up iac passage. pop it off and clean it out real good. you can also do a koeo test and see if you get any codes.
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Old 07-20-2006, 04:51 AM   #3
nacanitihs
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Vehicle: 1989, Mustang GT
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Default RE: low rough idle

Quote:
ORIGINAL: FiveLiterRiceEater
i like ur name btw.
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13.024 @ 105.8mph w/ 1.914 60' getting closer to 12s..

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Old 07-20-2006, 10:41 AM   #4
RacquetballRyan
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Default RE: low rough idle

I had a really rough idle, it was because the pump wasn't giving the engine enough gas.
If you still have the time or still up to it, try moving up to a 190lph or 255lph...it depends on everything you have on the engine.
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Old 07-20-2006, 02:14 PM   #5
88stangaruu
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Default RE: low rough idle

My 255 bumbed out and i just stuck a stocker in because its all i got till i get paid, im very curious about how much this is actually hurting my performance. It definatly is dragging *** on the top end now, only ran it up to there once, i worried about running lean at those higher rpms. I was watching my fuel pressure as i accelerated and it went from the 40's to near 10psi before i finally let off.

I also think its your IAC, as fiveliterriceeater said, get some carb and choke cleaner and spray it all in there and let it sit for a few min's. Then get scrub it really nice. Even get some compressed air and blow it out really nice.
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Old 07-21-2006, 03:16 AM   #6
95DkGrnGt
 
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Default RE: low rough idle

Thanks for the fast responses. I took off the IAC and cleaned it out with brake clean, it was all i had here, and it seems to be OK now. I have an idle of about 600-650 RPM and no surge with the A/C either.
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Old 07-21-2006, 03:16 AM
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