HIGH IDLE HELP

zackmatias

Member
Jul 27, 2021
4
3
13
23
Canada
Hey everyone, I have an 89 GT. When I have it idling with the clutch out (pedal not pushed in) it will always rev up to like 3000 and stay however when it idles with the clutch pushed in it idles fine. I know the mods don’t have anything to do with it because it was doing this last year before I re did the engine. I have checked for vacuum leaks and checked the throttle cable. The only thing that fixed it was adjusting the timing and keeping the spout unplugged but I noticed a drop in performance so I plugged the spout back in. Can someone please give me any suggestions?
 
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Dan02gt

10 Year Member
Mar 2, 2003
759
328
113
Greenville, NC
Sounds like the neutral sensing switch on your trans isn’t working correctly so the computer thinks your car is in gear and moving and it’s trying to prevent a stall. The switch is on the driver’s side top of the trans.
 
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zackmatias

Member
Jul 27, 2021
4
3
13
23
Canada
Sounds like the neutral sensing switch on your trans isn’t working correctly so the computer thinks your car is in gear and moving and it’s trying to prevent a stall. The switch is on the driver’s side top of the trans.
Okay I’ll give that a try! Thanks!
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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Massachusetts
Dump the codes and see if there is a code 67.


3K, however, is pretty high. So you might want to perform a smoke test (or use some carb cleaner) and see if you have any vaccum leaks? When my car had a NSS (code 67) issue, the idle would rise to maybe 1200-1500RPM tops.