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1989 Mustang LX 5.0 engine problem

  • Thread starter Thread starter mus89tang
  • Start date Start date Jun 12, 2019
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mus89tang

Member
Jun 12, 2019
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Minnesota
Jun 19, 2019
#21
  • Jun 19, 2019
  • #21
As you will see by the picture, the pump took care of the problem and I was able to move my Mustang with ease...mostly. It has plenty of power and no hesitation/stuttering. The only problem remaining is it doesn't idle at all and we found early on in the troubleshooting that the throttle air bypass valve wouldn't actuate at all. It was tested while still attached to the wiring with the car running and completely removed and running 12v directly to it, no movement at all. I suspect this is the problem with my idle, agreed?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,248
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Massachusetts
Jun 19, 2019
#22
  • Jun 19, 2019
  • #22
If you remove the iac off the engine but leave it powered, it won't move. It's designed to use engine vacuum to help move the piston. Bench testing it off the engine can sometimes give false results.

It's very possible it's bad, but I wouldn't rely on your test just yet.

Have you run the codes yet?
 
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mus89tang

Member
Jun 12, 2019
12
2
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Minnesota
Jun 20, 2019
#23
  • Jun 20, 2019
  • #23
I bought a new ICV yesterday, installed it and it now idles perfectly. Thanks to everyone for their input!
 
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