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HIGH IDLE HELP

  • Thread starter Thread starter zackmatias
  • Start date Start date Jul 27, 2021
  • Tags Tags
    5.0 foxbody high idle

zackmatias

Member
Jul 27, 2021
5
3
13
Canada
Jul 27, 2021
#1
  • Jul 27, 2021
  • #1
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?
 

Dan02gt

mazing how much gas smell came from that tiny hole
20+ Year Stangneter
Mar 2, 2003
909
415
113
Greenville, NC
Jul 27, 2021
#2
  • Jul 27, 2021
  • #2
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.
 
Reactions: zackmatias

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
Jul 27, 2021
#3
  • Jul 27, 2021
  • #3
Check for codes?
 

zackmatias

Member
Jul 27, 2021
5
3
13
Canada
Jul 27, 2021
#4
  • Jul 27, 2021
  • #4
Dan02gt said:
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.
Click to expand...
Okay I’ll give that a try! Thanks!
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,160
17,854
224
Massachusetts
Jul 29, 2021
#5
  • Jul 29, 2021
  • #5
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.
 
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