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Discussion Starter #1
So after I got my 4v swap back up and running I am having a few more problems. I got it tuned and it ran great, drove it around 60 miles and no problem at all. Now I go back to the car to go back home and everytime I stop at a light or stop sign the car turns off. It won't go unless I give it gas and then it'll drive. It drives fine after i get it moving but turns right back off once I slow down to stop. I just replaced all intake gaskets and plugs before i took it to the tuner. I even just swapped the iac out with a new one an it still does the something. I can't even get it to start now, it'll start and then turn right off unless I give it throttle. What could this problem be? Could it be a dirty or clogged fuel filter? The filter is pretty new also. Or something else? Also I'm not getting a single code either


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2002 Mustang Gt
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Not enough fuel maybe?

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US Air Force (retired)
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I've had a dirty MAF and a dirty TB cause stalling problems. I also had problems when the butterfly valve in the TB was closing too tight.
 

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Discussion Starter #4
I just tried another maf ad still nothing at all. I'm gonna change my fuel filter next and go from there. I also read somewhere about the vss sometimes causes a stalling problem. But if this were the case wouldn't my speedo not work too?


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Discussion Starter #5
So I talked to my tuner and sent him a datalog and he said "After looking at these logs a few times and playing them back and forth its hard to make any sense of them or why the car is doing what it is doing. Both long term and short term fuel trims look fairly tight and they aren't running excessively positive or negative and showing me there is a problem. Everything else you datalogged shows no smoking gun either. It's quite strange."

So I finally got the car to idle and warm up and drove it down the road, but its still stalling out when I come to a stop. While idling, I did notice a sound coming from the trans/clutch area. The stalling happens when I release the clutch pedal, so I was wondering if the clutch is'nt fully disengaging could this be the cause of the stalling problem. The reason why I'm asking is because towards the end of my drive I approached my road and popped the trans in neutral and the rpms started to drop real low around 783 rpms and then down to 382 rpms and then between 480 and low 500 rpms. The rpms begain to raise up to 600 once the car finally stopped on its own and then to around mid 900s once the idle worked itself out. Could the clutch be causing this problem?
 

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US Air Force (retired)
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I don't know much about a 4v swap. Did you put a new throttle body on it? If so you might need to open the butterfly valve in the TB a bit. The computer expects a certain amount of by-pass air through the TB. If it doesn't get it, it can lead to stalling.
 

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King Trashmouth
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So I finally got the car to idle and warm up and drove it down the road, but its still stalling out when I come to a stop. While idling, I did notice a sound coming from the trans/clutch area. The stalling happens when I release the clutch pedal, so I was wondering if the clutch is'nt fully disengaging could this be the cause of the stalling problem. The reason why I'm asking is because towards the end of my drive I approached my road and popped the trans in neutral and the rpms started to drop real low around 783 rpms and then down to 382 rpms and then between 480 and low 500 rpms. The rpms begain to raise up to 600 once the car finally stopped on its own and then to around mid 900s once the idle worked itself out. Could the clutch be causing this problem?
So if you're driving and just throw it in neutral, it will still undershoot? If it does, I would look at the IAC. Clean it out and make sure it's working right.

If it only does it during braking, it could be due to a vacuum leak. See if you can track one down with some carb cleaner.

Those would be my thoughts.
 

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Torchin tires...
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If it only does it during braking, it could be due to a vacuum leak. See if you can track one down with some carb cleaner.

Those would be my thoughts.
I was going to suggest this. I had a vacuum leak on my old notch and this helped alot. Had the same symptoms, stalling when slowing down and stopping, and crappy idle. Fine under load though. Def sounds like vacuum to me
 

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I had the same intermittent stalling with my '04 Mach 1 - the problem started after I installed a K & N CAI and loaded an SCT tune. My issue was inbound air turbulence through the K & N tripping the MAF sensor, giving the ECM a bad reading which told the IAC to fully close the throttle blades, which lead to a stall when returning to idle on decel. After significant road testing and data logging, you can review the IAC duty cycle numbers and ask your tuner to make minor adjustments to those numbers (as needed). It can take a while to completely debug as for me it only seemed to occur at certain RPM/mph speeds. My car's only got 19k miles on it.
 

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Where did you get your new iac from. Is it a genuine ford one or a parts store brand? Part store iac are junk and that still could be your problem.
 
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