I would replace the TPS sensor thats my guess without being there.
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Annoying idle problem on my 1999 GT HELP PLEASE!
ok ive had this weird RPM issue going on for a while, it will jump between 500 and 1000 rpm during idle times its also having trouble responding to the throttle in 1st and sometimes second gear, I will have to punch the gas then engage or it will somewhat bog down. This only happens right after I start it after driving a little while it runs great.
Also when I start the car it immediatley wants to stall unless i give it a little gas. I cannot figure out what this problem is!!
I have a 1999 Mustang GT manual trans.
The car has new fuel pump, new IAC valve, all new vacuum lines. It will not pull ANY codes on diagnostic test. Sensors all passed data point test. No leaks anywhere. Spark plugs all check out, so does the throttle stop screw.
I tried unpugging the MAF sensor and starting it, idled good but wasnt able to drive it with it unplugged it would want to stall out like usual.
I am really at my whits end trying to figure it out. Some shops said it could be my cold air intake thats the problem but id multiple shops are stumped on what it is.
If anyone has had this problem before and knows how to fix it please help me!! thanks
Also when I start the car it immediatley wants to stall unless i give it a little gas. I cannot figure out what this problem is!!
I have a 1999 Mustang GT manual trans.
The car has new fuel pump, new IAC valve, all new vacuum lines. It will not pull ANY codes on diagnostic test. Sensors all passed data point test. No leaks anywhere. Spark plugs all check out, so does the throttle stop screw.
I tried unpugging the MAF sensor and starting it, idled good but wasnt able to drive it with it unplugged it would want to stall out like usual.
I am really at my whits end trying to figure it out. Some shops said it could be my cold air intake thats the problem but id multiple shops are stumped on what it is.
If anyone has had this problem before and knows how to fix it please help me!! thanks
1 - 13 of 13 Posts
I don't think it's the TPS, based on issues I've had before that were due to TPS and symptoms were way different. But, if you want to check it, hook up to a scanner and view TPS voltage. At idle, it should hold pretty steady, and as throttle increases or decreases, voltage should do the same, steadily. If you don't have a scanner, you can use a voltmeter on resistance setting. Same thing here; look for a steady increase or decrease, with no sudden jumps or spikes in the reading as the sensor moves throughout it's range.I would replace the TPS sensor thats my guess without being there.
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I know you said you already did vacuum lines and IAC, but this issue is frustratingly classic to one of those two items being the issue.
Have you thought about having the alternator tested? It's a longshot, but something such as excessive AC ripple (bad diodes) can cause issues such as this.
I haven't had the alternator checked and ill have to get a shop to check the TPS, Im just stumped on why its not pulling codes at allI don't think it's the TPS, based on issues I've had before that were due to TPS and symptoms were way different. But, if you want to check it, hook up to a scanner and view TPS voltage. At idle, it should hold pretty steady, and as throttle increases or decreases, voltage should do the same, steadily. If you don't have a scanner, you can use a voltmeter on resistance setting. Same thing here; look for a steady increase or decrease, with no sudden jumps or spikes in the reading as the sensor moves throughout it's range.
I know you said you already did vacuum lines and IAC, but this issue is frustratingly classic to one of those two items being the issue.
Have you thought about having the alternator tested? It's a longshot, but something such as excessive AC ripple (bad diodes) can cause issues such as this.
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I don't know is that something I could look at myself?How is the PCv valve?
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Try getting some maf sensor cleaner and cleaning it.
ok I will try that, I hope it fixes it!Try getting some maf sensor cleaner and cleaning it.
Alright let us know if it works :bigthumbsup
Will do!Alright let us know if it works :bigthumbsup
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Blast! I cleaned the MAF and still no dice! Also when I shift into reverse it seems to drop RPMs like no other, and everytime i engage it in 1st it drops RPMs idk what it could be
The fact of the matter is this could be:
Have you disconnected the battery lately? If so, this could be part of the problem. Remember that each time the battery is disconnected, the PCM must RE-learn new idle/trim values. Sooooo it's normal to have a poor idle right after a battery disconnection.
Consider that if you are disconnecting the battery during trouble shooting, this will reset the IAC/PCM re-learning process. Just as well, if the battery voltage is dropping, this could reset the learning process.
My suggestion. Start with the easy stuff first before looking at the more difficult possibilities.
An ODB2 scanner with operational monitoring WILL make this easier to trouble shoot.
Check out:
http://www.allfordmustangs.com/foru...-dieing-idle-idling-rough-14.html#post2260649
- TPS
- vacuum leak
- bad IAC value
- bad PVC valve
- loose/worn throttle linkage
- weak throttle return spring
- Weak cylinder power balance
- bad TPS
- unstable/incorrect fuel pressure
- bad/weak/unstable battery or battery cables.
Have you disconnected the battery lately? If so, this could be part of the problem. Remember that each time the battery is disconnected, the PCM must RE-learn new idle/trim values. Sooooo it's normal to have a poor idle right after a battery disconnection.
Consider that if you are disconnecting the battery during trouble shooting, this will reset the IAC/PCM re-learning process. Just as well, if the battery voltage is dropping, this could reset the learning process.
My suggestion. Start with the easy stuff first before looking at the more difficult possibilities.
An ODB2 scanner with operational monitoring WILL make this easier to trouble shoot.
Check out:
http://www.allfordmustangs.com/foru...-dieing-idle-idling-rough-14.html#post2260649
I havent disconnected the battery in a couple weeks ok ill check out the link thanks!The fact of the matter is this could be:
- TPS
- vacuum leak
- bad IAC value
- bad PVC valve
- loose/worn throttle linkage
- weak throttle return spring
- Weak cylinder power balance
- bad TPS
- unstable/incorrect fuel pressure
- bad/weak/unstable battery or battery cables.
Have you disconnected the battery lately? If so, this could be part of the problem. Remember that each time the battery is disconnected, the PCM must RE-learn new idle/trim values. Sooooo it's normal to have a poor idle right after a battery disconnection.
Consider that if you are disconnecting the battery during trouble shooting, this will reset the IAC/PCM re-learning process. Just as well, if the battery voltage is dropping, this could reset the learning process.
My suggestion. Start with the easy stuff first before looking at the more difficult possibilities.
An ODB2 scanner with operational monitoring WILL make this easier to trouble shoot.
Check out:
http://www.allfordmustangs.com/foru...-dieing-idle-idling-rough-14.html#post2260649
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1 - 13 of 13 Posts
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