2004 Idle revving/dying issue
09-15-2011, 07:12 PM
#1
Thread Starter
Join Date: Aug 2010
Location: Missouri
Posts: 11
2004 Idle revving/dying issue
Hi there.
I have a 2004 mustang GT. About a week ago i started experiencing the issue with my car pertaining to the idle, I think. Every time I would start slowing down and come to a stop, the car would die; sometimes while I was still rolling, or other times when I was just sitting at the stop light. It didn't happen every time, but on about a 5 miles drive home from class 9/12 stop lights it did die. When I purchased the car I had also purchased the extra car package with it, in case something like this were to happen. After taking my car out there and them determining that my Idle Air Control Valve had gone bad, I found to my amazement that its not covered under warranty and that its a $500 fix. So I picked my car up(payed my $80 diagnostic fee, when it was still not conclusive) and decided to go a different route. Ordered the part it, got it in, relatively easy change. Here is where my next issue starts;
Start the car up. Idle's up, sounds like its running better. Great! Then realize after about 3 minutes that the idle is resting at around 2500RPM's. I figure maybe its just relearning the idle and so I drive around for about 20 minutes. Everything is going okay, until I go to stop. I push in the clutch and the idle jumps up from about 1,000RPM's from breaking, back to around 2500RPM's. I'm sitting at the stop light and the car is roaring, I'm looking embarrassed, and then my car's tack drops drastically fast and the car dies. I start my car up, the idle is screaming again, the light turns green, I can finally start going again and the car drives fine. It follows this pattern several times. I tried tapping the gas to get it to fall back down, and then it just gets stuck even higher around 3000RPM's. Sometimes it falls down, but hovers around 400-500RPM's and the lights dim, but the car doesn't completely die. I need some direction here. I'm not sure if the TPS needs replaced, or I need to adjust the IAC. I have no lights that come on, and for the diagnostic I ended up paying for at ford, it came back with no errors or anything. It's scary driving down the road and not knowing if I am going to be able to stop.
Thank you,
Skyler
I have a 2004 mustang GT. About a week ago i started experiencing the issue with my car pertaining to the idle, I think. Every time I would start slowing down and come to a stop, the car would die; sometimes while I was still rolling, or other times when I was just sitting at the stop light. It didn't happen every time, but on about a 5 miles drive home from class 9/12 stop lights it did die. When I purchased the car I had also purchased the extra car package with it, in case something like this were to happen. After taking my car out there and them determining that my Idle Air Control Valve had gone bad, I found to my amazement that its not covered under warranty and that its a $500 fix. So I picked my car up(payed my $80 diagnostic fee, when it was still not conclusive) and decided to go a different route. Ordered the part it, got it in, relatively easy change. Here is where my next issue starts;
Start the car up. Idle's up, sounds like its running better. Great! Then realize after about 3 minutes that the idle is resting at around 2500RPM's. I figure maybe its just relearning the idle and so I drive around for about 20 minutes. Everything is going okay, until I go to stop. I push in the clutch and the idle jumps up from about 1,000RPM's from breaking, back to around 2500RPM's. I'm sitting at the stop light and the car is roaring, I'm looking embarrassed, and then my car's tack drops drastically fast and the car dies. I start my car up, the idle is screaming again, the light turns green, I can finally start going again and the car drives fine. It follows this pattern several times. I tried tapping the gas to get it to fall back down, and then it just gets stuck even higher around 3000RPM's. Sometimes it falls down, but hovers around 400-500RPM's and the lights dim, but the car doesn't completely die. I need some direction here. I'm not sure if the TPS needs replaced, or I need to adjust the IAC. I have no lights that come on, and for the diagnostic I ended up paying for at ford, it came back with no errors or anything. It's scary driving down the road and not knowing if I am going to be able to stop.
Thank you,
Skyler
09-16-2011, 10:44 PM
#3
Thread Starter
Join Date: Aug 2010
Location: Missouri
Posts: 11
Thanks. I actually had replaced my IAC valve. Which ended up causing the second problem. Guess I got a bad one. I bought an aftermarket one, instead of giving Ford $350 dollars for the what they wanted.
09-17-2011, 06:36 AM
#4
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Make sure there are no air leaks after the MAF, also did you use a new gasket on the IAC?
Disconnect the battery for 5-7 minutes to clear the KAM and force the PCM to relearn the idle air trims.
With the engine idling disconnect the IAC electrical connector, the engine rpm should drop significantly or even stall.
You can check the IAC with a multi-meter, unplug the electrical connector and measure the resistance between the two terminals, it should be 6Ω to 13Ω.
Neither the IAC or TPS are adjustable, is the throttle stop screw has been mucked about with it will need to be reset--here is the procedure for doing that.
Disconnect the battery for 5-7 minutes to clear the KAM and force the PCM to relearn the idle air trims.
With the engine idling disconnect the IAC electrical connector, the engine rpm should drop significantly or even stall.
You can check the IAC with a multi-meter, unplug the electrical connector and measure the resistance between the two terminals, it should be 6Ω to 13Ω.
Neither the IAC or TPS are adjustable, is the throttle stop screw has been mucked about with it will need to be reset--here is the procedure for doing that.
09-17-2011, 04:58 PM
#5
Join Date: Jan 2007
Location: Texas
Posts: 35
Do as said earlier. Disconnect the battery for 25 minutes or so.
Also check the TPS. Check the air intake for leaks.
09-18-2011, 12:10 AM
#8
Thread Starter
Join Date: Aug 2010
Location: Missouri
Posts: 11
Thanks for all the help guys! I found out the first one I had put on it was junk, and ****ed up to begin with. Got a new another new one, and now everything is running fine! It was super frustrating this last week. Yes Ford wanted to charge me $350 for the part, and another $150 for the labour to put it on. Right around the $500 mark, for a 4 minute job. Outrageous! 50k in 2 1/2 years? I have put 14,000 miles on mine...that I purchased 2 1/2 years ago! haha. But seriously, thanks again for all the timely answers. I appreciate it. Love these forums!
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