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  • SN95 4.6L Mustang Tech

Probles With IDLE !

  • Thread starter Thread starter DanmMh
  • Start date Start date Jul 24, 2011
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DanmMh

New Member
Jul 20, 2011
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Jul 24, 2011
#1
  • Jul 24, 2011
  • #1
what zup, so i have the same problem, when i have the car on, the RPM goes down to 800 and i dont know why it goes alittle bit up around 1000 and then down, or goes down to 500, and sometimes a feels like it wants to turn off, I Clean the MAF, Throttle Body and the IAC, and still the sameeeee GRR ! you guys think it could be the TPS ? ? or a VACUUM leak ? ? Im in san diego and i need a good mechanic to help me find this problem, does any body knows one ?

THANKS
 

wmburns

SN Certified Technician
Aug 14, 2009
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Houston Texas
Jul 24, 2011
#2
  • Jul 24, 2011
  • #2
When was the last time the PCV value was replaced? Are all of the vacuum line leak free and in good shape? No rot, dry or brittle?

For more information on how to trouble shoot IAC issues, check out:
Is your mustang stumbling, dieing at idle or idling rough? - Page 14 - Ford Mustang Forums
 
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DanmMh

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Jul 20, 2011
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Jul 24, 2011
#3
  • Jul 24, 2011
  • #3
The Hoses look on a Ok condition, I inspect them all and they seems to be ok, and the PCV valve i bought it but i could not find it hehehe so i did not replaced it, can somebody show me how to replace it ? or where is it located ? or a link on how to change it ? so, you dont think it would be the TPS ?
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
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Houston Texas
Jul 24, 2011
#4
  • Jul 24, 2011
  • #4
Might be handy to know the model year of your car.

Did you read the information in the link? If so, you would know that this problem could be a vacuum leak, bad TPS, bad IAC, loose or worn TB linkage, bad or missing throttle return spring. The post gives information on how to narrow it down.

Seems very silly to me to have a PCV valve of unknown age and not replace it.

The TPS question is easily answered by monitoring the TP-MODE PID for a value of "C/T" whenever the throttle is closed. The TP-MODE should go to "P/T" whenever the throttle is depressed. If not, suspect a TPS problem.

The attached picture is from the V6 97 MY. For the V8 SOHC, the PCV valve is on the top center right hand valve cover. The 2001+ uses a high interference fit that has a 90 degree turn to remove.
 

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DanmMh

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Jul 20, 2011
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Jul 24, 2011
#5
  • Jul 24, 2011
  • #5
yeah i Red it , its a 2000 Mustang GT, Manual with 96K , i dont know this it a small issue but hard to troubleshoot, it could be a lot of things !i was reading on the link that you gave me that It could be the coil packs , ii started it doing the basic and ill have to keep moving foward until i find the probleM! ! ! GRRRRRRRR..... =(
 
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DanmMh

New Member
Jul 20, 2011
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Jul 24, 2011
#6
  • Jul 24, 2011
  • #6
I did the test, i Disconected the Electrical cable of the IAC and the engine shut down, i guess it will be a vacuum leak, ill take it tomorrow to do a vacuum test and ill see what the results are... or ill change the TPS sensor and see if it gets better. Thanks =D
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Jul 25, 2011
#7
  • Jul 25, 2011
  • #7
If you are going to revert to "parts changing", IMO it makes far more sense to replace the IAC. Since you stated the IAC was cleaned and the 2000 GT has a black vented IAC, there is one possible issue.

The black vented IAC has internal valves that need to close off the vent when the motor runs. Cleaning damages these vents which trades one problem for another.

A bad TPS is usually associated with a high idle.

Your reported symptom is idle "hunting". This is usually associated with a bad IAC, bad PCV valve, or loose TB linkage. The basic IAC functionally test indicates the IAC is working at some level.

Just to be sure, confirm that the cooling fans work on both speeds.

But the facts are that IAC's fail at a fairly high rate. So if the other usual causes have been partially ruled out, changing the IAC is not a bad plan of attack.
 
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Doomedfailure

Member
Jul 1, 2009
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Jul 26, 2011
#8
  • Jul 26, 2011
  • #8
I had a similar issue with my stang about 3 months ago I figured it was a vacuum leak. Anyways I did not find anything but I recently did a tune up new plugs wires and coils since they were old. And the problem was gone.
 
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DanmMh

New Member
Jul 20, 2011
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Jul 26, 2011
#9
  • Jul 26, 2011
  • #9
How much did you pay for all the parts for the tune up ? ? and did you buy only the coil wires and plugs ? or something else ?
 
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BraggStang

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Jul 2, 2006
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Jul 28, 2011
#10
  • Jul 28, 2011
  • #10
Seems like your IAC Is bad. I had the same problem. My car would idle normal with the AC off and when I put a load when the AC was turned on it would die. I replaced the IAC and it corrected the problem. Go to Auto Zone and order one for 63 bucks.
 
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