stalls once in a while out when in gear waiting for a light
- Thread starter rockyracoon
- Start date
-
Sponsors (?)
streethorse
15 Year Member
wmburns
SN Certified Technician
How to Test the IAC
The 1996 likely has the IAC with the black vent. These can not be cleaned. Replace.
The IAC without the vent can be cleaned. However, be prepared that this is likely a temporary solution.
The IAC is prone to combustion by-products gumming up the air passage ways. This affects air flow through the IAC. Further, the kind with the vent has a diaphragm check valve that will leak with age.
To perform a basic IAC function test, disconnect the electrical connector. The engine RPM’s should decrease or the engine die out right. The engine should die if the IAC does not have the vent. The engine may die or slow down with the vent.
If the IAC fails the basic test then either the IAC is bad, vacuum leak, EPAP purge solenoid stuck open, or no electrical signal from PCM to IAC.
It is always a good idea to check for vacuum leaks. Also clean the MAF.
If the IAC is stuck closed, this can cause a no start condition. If the motor starts with the accelerator held partially open, suspect bad IAC.
I suspect that your IAC is basically working but is partially blocked internally, hence the reason for the slow idle. AutoZone sells a reasonably priced non-Ford replacement. I have had good luck with them.
I just replaced my IAC for nearly the same symptoms. Car would occasionally stall when cold in neutral. When hot the idle would “flare” unexpectedly. New IAC fixed it right up.
After replacement either remove the battery negative or allow the car to idle for 1 full minute AC off. Then another full minute AC on.
For 1999+ cars, best to disconnect the battery.
May take several minutes/hour(s) of driving for the PCM to re-learn all of the idle/Fuel trim values. Depends upon year, transmission, and how much time is spent stopped with foot on the brake.
The 1996 likely has the IAC with the black vent. These can not be cleaned. Replace.
The IAC without the vent can be cleaned. However, be prepared that this is likely a temporary solution.
The IAC is prone to combustion by-products gumming up the air passage ways. This affects air flow through the IAC. Further, the kind with the vent has a diaphragm check valve that will leak with age.
To perform a basic IAC function test, disconnect the electrical connector. The engine RPM’s should decrease or the engine die out right. The engine should die if the IAC does not have the vent. The engine may die or slow down with the vent.
If the IAC fails the basic test then either the IAC is bad, vacuum leak, EPAP purge solenoid stuck open, or no electrical signal from PCM to IAC.
It is always a good idea to check for vacuum leaks. Also clean the MAF.
If the IAC is stuck closed, this can cause a no start condition. If the motor starts with the accelerator held partially open, suspect bad IAC.
I suspect that your IAC is basically working but is partially blocked internally, hence the reason for the slow idle. AutoZone sells a reasonably priced non-Ford replacement. I have had good luck with them.
I just replaced my IAC for nearly the same symptoms. Car would occasionally stall when cold in neutral. When hot the idle would “flare” unexpectedly. New IAC fixed it right up.
After replacement either remove the battery negative or allow the car to idle for 1 full minute AC off. Then another full minute AC on.
For 1999+ cars, best to disconnect the battery.
May take several minutes/hour(s) of driving for the PCM to re-learn all of the idle/Fuel trim values. Depends upon year, transmission, and how much time is spent stopped with foot on the brake.
trombonedemon
Well-Known Member
Yea what W.M. Burns said, I think I am going to follow his posts around and just say, "Yea what W.M. Burns said," What do you do for a livin' all of your post are like talking to a Ford master tech! Oh yea, thanks for helping me out of my windshield wiper bind!
wmburns
SN Certified Technician
Thanks so much for the kind words. I am glad I was able to help.
I had someone else on another forum ask me that same question. If it’s OK, I will re-use the reply.
I tell my kids to not divulge too much personal information over the internet. Let’s see how multiple choice works.
1 NASA rocket scientist. Cars are just a side line.
2 Proctologist. Means I do not have to clean hands going from job to hobby.
3 NASCAR crew member. Hint. I am the fat one changing the tire on the Dana Kirkpatrick TV commercial.
4 Computer programmer. The kind with a pocket protector and all.
Seriously, I work on cars for a hobby and have for a long time. We have 5 family cars plus “project” cars. I am avid reader and will read technical manuals for fun. I have copies of Ford service CD's for the 1996, 2000, and 2003 model years.
Also have several magazine subscriptions.
Finally, when I travel, I stay in a Holiday Inn.
patman0911
Founding Member
Hey, wmburns, since we're piling on the appreciation here... you should compile everything you've learned about the IAC and idle systems into one thread for future reference. You've posted a lot of fantastic info about it over the last few weeks.
wmburns
SN Certified Technician
You asked for it. It's in the resources section.
Troubleshoot IAC idle problems 1996-2004
http://www.stangnet.com/mustang-forums/resources/troubleshoot-iac-idle-problems-1996-2004.13/
Troubleshoot IAC idle problems 1996-2004
http://www.stangnet.com/mustang-forums/resources/troubleshoot-iac-idle-problems-1996-2004.13/
Similar threads
