I've had my 99 GT for roughly six or seven weeks now and since I've had it I've been having idle issues on and off. I've replaced the IACV with a brand new motorcraft part and it didn't fix the issue. I've even put on a Plenum and TB and I've replaced the TPS. There aren't any disconnected vacuum lines and nothing appears to be ruptured or cracked. Sometimes the car idles fine and other times it wont idle at all. I have XE262AH cams and a factory tune and im curious if that may be some of the cause of my idle issues. I just recently installed a catted X-pipe and the idle issues are more common (my guess is from unplugging the battery and resetting the ecu). Any help and/or advice would be greatly appreciated. Im stumped and frustrated. I've searched and searched and can't find anything to fix my issues.
Intermittent Idle Issues
StangAddiction
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I've had my 99 GT for roughly six or seven weeks now and since I've had it I've been having idle issues on and off. I've replaced the IACV with a brand new motorcraft part and it didn't fix the issue. I've even put on a Plenum and TB and I've replaced the TPS. There aren't any disconnected vacuum lines and nothing appears to be ruptured or cracked. Sometimes the car idles fine and other times it wont idle at all. I have XE262AH cams and a factory tune and im curious if that may be some of the cause of my idle issues. I just recently installed a catted X-pipe and the idle issues are more common (my guess is from unplugging the battery and resetting the ecu). Any help and/or advice would be greatly appreciated. Im stumped and frustrated. I've searched and searched and can't find anything to fix my issues.
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Well, you've done the obvious things already.
Did the idle issue start after installing the cams? After the tb and plenum?
What I would do regardless, is get it professionally tuned. There's a shop in Auburn that does great work. $150 and they'll spend hours on your car to get peak power. That might fix your idle as well.
Did the idle issue start after installing the cams? After the tb and plenum?
What I would do regardless, is get it professionally tuned. There's a shop in Auburn that does great work. $150 and they'll spend hours on your car to get peak power. That might fix your idle as well.
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I bought the car with cams already in it. It has always had intermittent idle issues from day one. It just seems to always get much worse when I disconnect the battery. I've been to that shop. Its called the Mustang Shop. They actually quoted me $300 for a tune if I have a programmer. A programmer is $380. There's always the possibility that it wont fix the issue, then im almost $700 out and still have the same problem...
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$300? Damn, that's double what mine was...
But that's true. Someone with more idle knowledge should chime in soon.
Hope you get it figured out soon!
But that's true. Someone with more idle knowledge should chime in soon.
Hope you get it figured out soon!
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They're also primarily open during the week. Im military, I don't have time off during the week to drive way out there before they close. I really don't believe its the tune though. It was just a thought. EGR maybe? I dunno.
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Is the idle surging? What exactly is it doing? Usually, idle issues are related to the iac or vacuum leaks. You can try cleaning the maf, but I'd doubt that's the problem. I would think if it were a tune issue it would be far less random than you're indicating, but if you're running aftermarket cams on a factory tune, it certainly could be a part of the issue. If you have a brand new Motorcraft iac, then I would start searching for a vacuum leak.
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I had a similar issue with mine when the a/c cycled at idle the rpms would drop 3-500 rpms.
I had noticed that looking under the hood with the car running the belt tensioner was moving all over the place. I replaced it with one from rockauto.com and it fixed my issue. Maybe check your belt tensioner?
I had noticed that looking under the hood with the car running the belt tensioner was moving all over the place. I replaced it with one from rockauto.com and it fixed my issue. Maybe check your belt tensioner?
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I can't express how much appreciate you guys' input. The idle isn't surging at all. Sometimes when I press the clutch in, it'll fall really slow after it gets to 1000 and instead of stopping at 500 and picking back up like it normally would, it just continues to drop until it dies. Seems to be more stable after the car warms up though. When it's cold outside and the engine hasn't warmed up its noticeably more likely to happen. Sometimes ill be sitting at a light and it just drops out. Usually it starts right back up but most times after it cuts off its hard to get it to want to idle. I have to throttle it a little until it starts to hold idle again.
I actually have 3 IACVs. All motorcraft. The one that came on the car, a used one, and the new one (currently on the car now). If used all three and problem persisted. I put my IACV on my friends crown vic and he ran his car the entire weekend with no issues so I've pretty much ruled that out.
Someone keeps suggesting I adjust the idle screw, but that's a bandaid. I don't want to do that. I foresee that leading to high idle when cold. Im going to check all the vacuum lines again. As far as the belt tensioner, that sounds like something good to look into. Ill check it out. I don't typically use the a/c though. I guess the defrost uses the compressor also right? Not sure.
Apparantly the computer has an idle reset procedure? Someone told me to run the engine for 5 mins with no load after it has warmed up and then 5 mins with Max a/c, radio on, and headlights on. So I did that and my car consistently cuts off about 2-3 mins into running under the increased electrical load. I tried it 3 times, happened every time.
I actually have 3 IACVs. All motorcraft. The one that came on the car, a used one, and the new one (currently on the car now). If used all three and problem persisted. I put my IACV on my friends crown vic and he ran his car the entire weekend with no issues so I've pretty much ruled that out.
Someone keeps suggesting I adjust the idle screw, but that's a bandaid. I don't want to do that. I foresee that leading to high idle when cold. Im going to check all the vacuum lines again. As far as the belt tensioner, that sounds like something good to look into. Ill check it out. I don't typically use the a/c though. I guess the defrost uses the compressor also right? Not sure.
Apparantly the computer has an idle reset procedure? Someone told me to run the engine for 5 mins with no load after it has warmed up and then 5 mins with Max a/c, radio on, and headlights on. So I did that and my car consistently cuts off about 2-3 mins into running under the increased electrical load. I tried it 3 times, happened every time.
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i would perform the base idle rest procedure and see if that works, its been known to help fix a wide variety of issues, including mine recently. I hope it helps
Disconnect the battery's negative terminal to reset/clear the computer's memory. Leave it disconnected for 30 minutes.
Disconnect the plug going to your idle motor which is located on the front of your throttle body.
Reconnect your battery's negative terminal.
Start the engine, and set the idle to the point where the vehicle feels like its going to die with the stop screw on the bottom of the throttle body.
Turn off the engine.
Reconnect the plug on the idle motor.
Make sure all accesories (radio, blower motor, a/c, lights, etc) are off and start the engine.
Let engine run for two minutes.
Turn engine off and wait two minutes then restart engine and let idle for two minutes with all accesories on.
Edit: if that doesnt help im betting on electrical issue as in alternator or battery, that can cause idle problems if your ignition system isnt getting the juice it needs
Disconnect the battery's negative terminal to reset/clear the computer's memory. Leave it disconnected for 30 minutes.
Disconnect the plug going to your idle motor which is located on the front of your throttle body.
Reconnect your battery's negative terminal.
Start the engine, and set the idle to the point where the vehicle feels like its going to die with the stop screw on the bottom of the throttle body.
Turn off the engine.
Reconnect the plug on the idle motor.
Make sure all accesories (radio, blower motor, a/c, lights, etc) are off and start the engine.
Let engine run for two minutes.
Turn engine off and wait two minutes then restart engine and let idle for two minutes with all accesories on.
Edit: if that doesnt help im betting on electrical issue as in alternator or battery, that can cause idle problems if your ignition system isnt getting the juice it needs
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I don't. Testing the battery is a definite option though. I'll make plans to do that. I may even remove the alternator and test it as well. Takes what? 5 mins to take off? Lol
That's some really good info there. I really appreciate you guys for the help. Im on duty today, so tomorrow I'll try some of the suggestions you guys posted.
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Food for thought i went through two tps before i found one that worked out right and that fixed my high hanging idle.
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I've take everyone's advice. Still having issues. I spoke to a couple of guys familiar with tuning mustangs, and both guys insist that it's probably the cams, or the tune rather. I also spoke to Joe at trick tuners and he's saying the same thing, so I'm going to get this thing tuned and hopefully that will solve my issues.
In any instance, I really appreciate the help guys. I can't believe I left this forum for 4-5 years. I almost forgot what it's like to be on a forum where members are actually willing to help you instead of screaming "search" and criticizing your every move. In reality, we're all on here for the same reasons.
Again, I appreciate the help guys. :thumb:
In any instance, I really appreciate the help guys. I can't believe I left this forum for 4-5 years. I almost forgot what it's like to be on a forum where members are actually willing to help you instead of screaming "search" and criticizing your every move. In reality, we're all on here for the same reasons.
Again, I appreciate the help guys. :thumb:
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We all try to help each other.
Let us know how it turns out!
Let us know how it turns out!
I'm curious about the shutoff at full electrical load. Mine stalls almost immediately with every electoral component on. The general rules are batteries cause starting problems and alternators are when running. You can test the voltage with a multimeter on the battery. It should be 12.5v engine off and 14.1v at idle.
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The vicious snow help up my Mustang Life. Lol
Anyways, I've received a base tune from Joe @ Trick Tuners. Car drives 10x better than it ever has. 45 mins of stop and go traffic around town. No issues whatsoever. I even tried to make the car stall and it endured.
I can't wait to get the timing dialed in on the tune. I'm all happy and excited now. Maybe I need to get some gears in this beast. Oh the temptation. :naughty:
Anyways, I've received a base tune from Joe @ Trick Tuners. Car drives 10x better than it ever has. 45 mins of stop and go traffic around town. No issues whatsoever. I even tried to make the car stall and it endured.
I can't wait to get the timing dialed in on the tune. I'm all happy and excited now. Maybe I need to get some gears in this beast. Oh the temptation. :naughty:
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Should change that face palm in your sig made me laugh.
made me laugh.
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Lol. It's how I legitimately felt. I had idle issues from day one. They just became more and more common as I began adding more and more mods. It would be nice if the weather would clear up so I could swap my X-pipe for these ProChambers.Should change that face palm in your sig
Once again, I really appreciate the help guys. I resolved my issue and gained some pretty valuable knowledge that I didn't know before.
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