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Coming to an idle problem

  • Thread starter Thread starter green_drop
  • Start date Start date Aug 12, 2004
G

green_drop

New Member
May 29, 2003
43
0
0
Aug 12, 2004
#1
  • Aug 12, 2004
  • #1
When i rev up my car the rpms drop quick to 1500 and then slowly makes its way to an idle takes (5sec) I counted this is the most annoyning thing in the world and I thought it was my jacobs ignition box but it wasn't. I have no idea how to make it drop quick like it used to and how it does on all my other buddies mustangs.
 

mo_dingo

20+ Year Stangneter
Aug 26, 2003
3,031
2
58
Tucson, AZ
Aug 12, 2004
#2
  • Aug 12, 2004
  • #2
Have you played with the idle settings on the car???? What mods do you have?

If your idle settings are good, then my guess would be you IAC valve has a lot of buildup, and needs cleaning. Or, you will need a completely new one. If you don't know if the idle settings are good, you need to check. Do a search for "hanging idle". You will find out how.

I went through a fiasco w/ this sensor, so trust me on this. If you decide it's the problem and want to replace it, get it at Pep Boys. The autozone one did not work for me and someone else I know. Once they got the Pep Boys part, everything was well!
Scott
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 13, 2004
#3
  • Aug 13, 2004
  • #3
does it do it always or just when coming to a stop light? if the latter, dont over look that a function of the VSS is to hold the idle at 1500 RPM or so, when moving.

have you checked for vac leaks? a leak can create a hanging idle (any speed). a stockish motor should pull 15-20" at idle.

good luck.
 
G

green_drop

New Member
May 29, 2003
43
0
0
Aug 13, 2004
#4
  • Aug 13, 2004
  • #4
it does it coming to a stop light which i understand that is fine. But when i am completely stopped and just rev up it still takes forever to come down
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 13, 2004
#5
  • Aug 13, 2004
  • #5
pull codes, check for vac leak and clean IAC (amongst other things, but id do those first). my two cents.
good luck.
 

GTJake

Founding Member
Oct 28, 2002
3,049
0
56
Ann Arbor, MI
Aug 14, 2004
#6
  • Aug 14, 2004
  • #6
New TPS fixed the hanging idle on my car.

Jake
 
T

topdri

Founding Member
Jun 13, 2000
70
0
0
Durham, NC
Aug 14, 2004
#7
  • Aug 14, 2004
  • #7
I have an 89 mustang and I have replaced the tps, iac, maf, and coolant sensor - I still have an issue with a hanging idle. It jumps up to as high as 2200 RPMs. I turn the car off and that may fix it for a bit. I have my mechanic stumped now, of which is very hard to do.

Any ideas?
 
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