1999 cobra idle issues

[Rippinwfo01]

i recently bought a 1999 mustang cobra with 58k miles. After the car warms up it wont idle. it dies once you pull up to a stop sign etc. i changed mass air meters and no change really. i took it to autozone and a code for the ecm showed up and for the speedometer. if anybody has any experience with this problem any information would be greatly appreciated.

 

[01yellercobra]

Did you try cleaning the IAC?

 

[Rippinwfo01]

No thats the one thing i havent done. i was going to tommorow or buy another one. the car sat for around a year so maybe it could be the problem.

 

[Nightmare90gt]

Have you check the tps voltage

 

[Rippinwfo01]

No i havent checked that. Sorry for my ignorance but what is tps voltage exactly. The car has different cams could it maybe need tuned?

 

[Rippinwfo01]

Also one of the codes that showed up when i ran them at autozone says the ecm does not recongnize the vehicles ID.

 

[Nightmare90gt]

Tps = throttle position sensor

 

[BigEasy]

Id check out your MAF, IAC, TPS like everyone else has said. Have you taken off your Throttle body to clean or change it out? If so its most likely ur tps voltage, the tps voltage should be around .98 but all cars are alittle diff. Did it have the stock 80mm maf sensor on it?

 

[RX1Cobra]

I bet its the vehicle speed sensor. Its on the trans and pretty easy to change.

 

[Rippinwfo01]

im going to have those things checked out. i got a guy coming to look at it sometime who knows more than me. i havent took the throttle body off and no it didnt have the stock mass air on it. it wasnt even the right one. apparently someone changed it out and im wondering now if they didnt mess the computer up. when i scan the codes it says ecu does not recognize the vehicles ID. im going to have it tuned soon also hoping that fixes it if i cant figure out whats wrong.

 

[Rippinwfo01]

and speaking of that @rx1 cobra it has a tremec 3550 and the speedometer doesnt work. when i ran the codes it said something about the vehicles speed sensor and the ecm not recognizing the vehicles id

 

[BigEasy]

Well i know if it had the wrong maf on it without a tune its not going to run right. You installed a 80mm back on it? Does it have the stock Throttle Body?

 

[Rippinwfo01]

it has the stock one back on it and has a stock throttle body. it still does the same thing. it wants to pop and crack then die. only thing done to the motor supposedly is FR500 cams and ported and polished heads

 

[Rippinwfo01]

it kinda acts like the computer is ****ed but last car i had with computer issues wouldnt hardly run at all

 

[BigEasy]

You can try to tap on the tps, it worked for me after i took off and cleaned my TB, Plenum & Intake i had idling problems. Im not sure about the speed sensor man.

 

[01yellercobra]

If it didn't have the stock MAF and was tuned for it then it's not going to run very well with a stock MAF. My understanding is the FR500 cams lope at idle. So if it doesn't lope then you may not have the cams. And not having a working speed sensor can cause some issues.

What all did the seller say about the car?

 

[ashleyroachclip]

I have an 01 Cobra drive train transplanted into a 91 Fox body coupe .
The symptoms you describe are in line with what others have said about the vss, vehicle speed sensor.
And the iac idle air control .
The iac can be cleaned , no special tools required .
The vss has 3 wires .
One is the ground and the other 2 are signal and signal return.
Make sure it is connected properly , and yes this also controls the speedometer as well as idle and return to idle when coming g to a stop .

 

[Rippinwfo01]

as far as i know the vehicle speed sensor isnt even hooked up to the transmission

 

[Black*Death]

Don't forget the EGR valve. I wasn't stalling but getting a surge at idle with horrible gas miles. New IAC helped but replacing the EGR essentially fixed the problem