car dies when coming to stops at random?

[kingcobra10]

FIXED!!!!!!My 96 cobra is having an issue with coming to a stop. Sometimes when i slow down to stop and press the clutch in the car dies. It doesn't do it every time but two or three times a drive. Seems to only happen once the car is warm. Car runs fine and starts right back up. no lose in power or anything like that. just dies randomly?


If any of you guys have an idea of what this could be please chime in.


also I changed the face of my cluster to an 03 Cobra face and needles (don't know if this could have an effect) I still have the stock cluster in the car just the face and needles were changed.


thanks,
Brandon.

 

[Duncan]

Sounds like the infamous I.A.C. issue. Try cleaning it.

http://www.moddedmustangs.com/cleaning-your-iac.html

 

[FSSNK]

Idle Air Control

 

[NastyNate420]

Mine was the Maf screen also clean the maf while your at it. ......Could also be IAC

 

[luke87gt]

I had this same problem...

Believe it or not it seemed to be MAF related for me. I cleaned the MAF and rotated it, and have not had this issue again.

 

[mwolson]

Is your speedometer working?

Do you have larger than stock injectors?

 

[SVT Pille]

Mine does it too, the IAC on these cars blow. Me and my tuner solved the problem by drilling a "bleed hole" in the throttle body plate so it wouldn't choke at idle. Worked really well for me.

 

[mwolson]

Mine does it too, the IAC on these cars blow. Me and my tuner solved the problem by drilling a "bleed hole" in the throttle body plate so it wouldn't choke at idle. Worked really well for me.

Sorry to disagree, but this will treat the symptom, but not the cause. You can accomplish the same thing as drilling a hole by adjusting the throttle stop screw to open the TB blade a hair. But that will then probably screw up the idle system.

SVT Pille, you will see if you datalog your idle that it is probably now out of kilter. You want to see your ISC duty cycle to be around 35% and the ISC integrator to be around 0. Your tuner should know this. You set your ISC duty cycle by slowly adjusting the TB stop screw while datalogging. Your tuner should then set the ISC integrator to 0 by adjusting the idle air tables in the tune.

The PCM uses air for coarse control of idle, and it uses spark advance for fine control of idle. You will also want to log your spark source to see if it is at a steady 9 when you idle. That means spark is in control of idle.

Idle problems can really be difficult to solve. If you try to solve them without datalogging, you are just shooting in the dark. And the first thing to do is ensure you don't have any leaks of metered air with a smoke test before you even start trying to fix idle issues.

However, the OP's problem is not an idle problem, it is a deceleration problem. I have seen this in cars that have larger than stock injectors, and that is solved by tweaking the dashpot function in the tune.

I have also seen the lack of a good VSS signal at the PCM cause this problem. The PCM uses a more aggressive dashpot function when the car is stopped than it does when the car is moving. If the PCM does not see a good VSS signal, it thinks the car is stopped and drops the RPMS very fast. But the load on the engine from the power brakes and steering is too much and causes the engine to stall. So this symptom can also be caused by the lack of a VSS signal to the PCM.

 

[DVJ38]

Sorry to disagree, but this will treat the symptom, but not the cause. You can accomplish the same thing as drilling a hole by adjusting the throttle stop screw to open the TB blade a hair. But that will then probably screw up the idle system.

SVT Pille, you will see if you datalog your idle that it is probably now out of kilter. You want to see your ISC duty cycle to be around 35% and the ISC integrator to be around 0. Your tuner should know this. You set your ISC duty cycle by slowly adjusting the TB stop screw while datalogging. Your tuner should then set the ISC integrator to 0 by adjusting the idle air tables in the tune.

The PCM uses air for coarse control of idle, and it uses spark advance for fine control of idle. You will also want to log your spark source to see if it is at a steady 9 when you idle. That means spark is in control of idle.

Idle problems can really be difficult to solve. If you try to solve them without datalogging, you are just shooting in the dark. And the first thing to do is ensure you don't have any leaks of metered air with a smoke test before you even start trying to fix idle issues.

However, the OP's problem is not an idle problem, it is a deceleration problem. I have seen this in cars that have larger than stock injectors, and that is solved by tweaking the dashpot function in the tune.

I have also seen the lack of a good VSS signal at the PCM cause this problem. The PCM uses a more aggressive dashpot function when the car is stopped than it does when the car is moving. If the PCM does not see a good VSS signal, it thinks the car is stopped and drops the RPMS very fast. But the load on the engine from the power brakes and steering is too much and causes the engine to stall. So this symptom can also be caused by the lack of a VSS signal to the PCM.

Very informative as always. I wish I had a tuner and computer program to mess around with so I could see exactly what you're talking about! Maybe in a year or two lol :coolman:

OP, my car did this last summer to me as well. It was less frequent though, only about 3 times total last summer. It can be very dangerous if you're coming up to a busy intersection though so I decided to take a possible step towards resolving the issue by replacing the IAC valve. Ford no longer makes one of course, so I did some reading and heard people had good luck with the IAC from Advanced Auto. I installed that one in my car and so far so good. I'll have to wait until more time goes by before I am satisfied I fixed it though. You should clean your maf also with some maf sensor cleaner. They make a special cleaner for it you can buy at the auto parts stores. These would be two relatively inexpensive ways of trying to solve the problem.

 

[zinc]

My car did this twice since I bought it a couple weeks ago im glad I decided to browse the forums tonight. Op: hopefully we can both solve the issue.

 

[DVJ38]

My car did this twice since I bought it a couple weeks ago im glad I decided to browse the forums tonight. Op: hopefully we can both solve the issue.

Yours is boosted and I'd assume has a different fuel system and tuning so it might be more complicated of an issue than the OPs. Side note: I demand exhaust vids! Kooks long tubes with Dr. Gas X pipe! :rockon:

 

[mwolson]

My car did this twice since I bought it a couple weeks ago im glad I decided to browse the forums tonight. Op: hopefully we can both solve the issue.

I agree with DVJ38. I suspect you just need a tune tweak, assuming your speedo is working.

Although it can never hurt to clean the IACV and MAF.

 

[zinc]

Ill clean both and see if it helps at all. If not I'll take it to my tuner and have it checked.

best i could get you is an iphone video but ill try.

 

[mwolson]

Never touch the MAF wire. I spray mine with electrical contact cleaner. Others use brake cleaner.

A dirty MAF can particularly be a problem if you over-oil your cleanable air filter.

 

[mmustangsrus]

Very informative as always. I wish I had a tuner and computer program to mess around with so I could see exactly what you're talking about! Maybe in a year or two lol :coolman:

OP, my car did this last summer to me as well. It was less frequent though, only about 3 times total last summer. It can be very dangerous if you're coming up to a busy intersection though so I decided to take a possible step towards resolving the issue by replacing the IAC valve. Ford no longer makes one of course, so I did some reading and heard people had good luck with the IAC from Advanced Auto. I installed that one in my car and so far so good. I'll have to wait until more time goes by before I am satisfied I fixed it though. You should clean your maf also with some maf sensor cleaner. They make a special cleaner for it you can buy at the auto parts stores. These would be two relatively inexpensive ways of trying to solve the problem.

yea i found this out today i`m chasing this issue & more right now !

Never touch the MAF wire. I spray mine with electrical contact cleaner. Others use brake cleaner.

A dirty MAF can particularly be a problem if you over-oil your cleanable air filter.

yea this is true !!!


ALSO I WONDER IF YOU CAN PUT THE 01-04 IAC MOTOR & CURE SOME OF THE WIERD IAC ISSUES THEY HAVE !!!

since the iac`s have the baffle up top i heard you cant clean them of it will damage them is this true ? ???

 

[96snake719]

My car did this also, turns out mine was a bad connection where the connector hooked into the VSS. So dont overlook that VSS it could very well be that!

 

[kingcobra10]

UPDATE: cleaned the IAC and MAF, drove the car for 25 minutes didn't die. thanks SVTP

 

[DVJ38]

My car did this also, turns out mine was a bad connection where the connector hooked into the VSS. So dont overlook that VSS it could very well be that!

Good call.

UPDATE: cleaned the IAC and MAF, drove the car for 25 minutes didn't die. thanks SVTP

:rockon:
Nice, glad that the cheapest way possible worked! If it starts to do it again I would just replace the IAC with a new one.

 

[1989Gt.]

Can a iac cause power issues up in the rpms?

 

[mwolson]

Not really.