2003 mustang v6, idle issue
- Thread starter jduffin
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wmburns
SN Certified Technician
How to trouble shoot low Idle IAC
Manual or automatic? I will assume an automatic.
Clean the MAF. Use only cleaner designed for the purpose. This is important.
For low idle concerns, look for vacuum leaks. Especially in the bypass line to the IAC.
Low idle can also be cause by weak ignition. What is the condition of the spark plugs, wires and coil pack?
Finally, If the inside of the IAC is blocked with PCV blow by (from normal) age, it will not pass enough air to maintain the correct idle. Suggest replacing since a great deal of time it is the IAC.
Check out post 3
http://www.stangnet.com/mustang-forums/810729-starts-but-dies-idle-help.html
Manual or automatic? I will assume an automatic.
Clean the MAF. Use only cleaner designed for the purpose. This is important.
For low idle concerns, look for vacuum leaks. Especially in the bypass line to the IAC.
Low idle can also be cause by weak ignition. What is the condition of the spark plugs, wires and coil pack?
Finally, If the inside of the IAC is blocked with PCV blow by (from normal) age, it will not pass enough air to maintain the correct idle. Suggest replacing since a great deal of time it is the IAC.
Check out post 3
http://www.stangnet.com/mustang-forums/810729-starts-but-dies-idle-help.html
wmburns
SN Certified Technician
Have you cleaned the MAF?
Does your power steering pump have an electricial connector on it? Is it connected? Some power steering pumps have a pressure switch to let the PCM know when load increases. This enables the PCM to increase idle to compensate.
Consider changing the IAC just because oftentimes it is the problem especially on older/high mileage cars. Especially the IAC with the black vent.
Have you reveiwed the other items listed?
If your IAC has a 1/2" vent line attached, that is the bypass line. Some IAC's have an internal bypass line. In which case. cleaning/replacing is the only option.
Regarding cleaning. Don't clean the IAC with the black vent. Replace it.
The non-vent can be cleaned. However, 50/50 chance it will be effective. Cleaning is most effective if the problem is clogging due to PCV blow by.
If you still need help, post pictures of your IAC. Also the resutls of everything done and will go from there.
Does your power steering pump have an electricial connector on it? Is it connected? Some power steering pumps have a pressure switch to let the PCM know when load increases. This enables the PCM to increase idle to compensate.
Consider changing the IAC just because oftentimes it is the problem especially on older/high mileage cars. Especially the IAC with the black vent.
Have you reveiwed the other items listed?
If your IAC has a 1/2" vent line attached, that is the bypass line. Some IAC's have an internal bypass line. In which case. cleaning/replacing is the only option.
Regarding cleaning. Don't clean the IAC with the black vent. Replace it.
The non-vent can be cleaned. However, 50/50 chance it will be effective. Cleaning is most effective if the problem is clogging due to PCV blow by.
If you still need help, post pictures of your IAC. Also the resutls of everything done and will go from there.
wmburns
SN Certified Technician
It doesn't sound like you actually read the post. If you had, the post tells you that the black vent provides bypass air for starting. The post states that the black vent version is less likely to die when the electrical line is disconnected. The key thing the basic functional test is looking for is the CHANGE(lower) in RPM's. No change equals no IAC function.
Since you have now confirmed the black vent version, do yourself a favor and buy a new one. The black vent version can not be effectively cleaned.
If you still still wish to test, an ODB2 scanner with the ability to monitor operational parameters will be needed.
Again, as mentioned before, there are multiple reasons for a slow idle. Tests are needed to rule in/out the various causes. Sometimes you just need to start at the most likely place and work from there.
OBTW, should you decide to clean the black vent IAC, please don't post any requests for more help should it not work. Note, I am not going to tell you with absolute certaintaty it won't work because sometimes it does. However, the odds favor the results to be only temporary. Or one set of problems will be traded for another.
Good luck.
Since you have now confirmed the black vent version, do yourself a favor and buy a new one. The black vent version can not be effectively cleaned.
If you still still wish to test, an ODB2 scanner with the ability to monitor operational parameters will be needed.
Again, as mentioned before, there are multiple reasons for a slow idle. Tests are needed to rule in/out the various causes. Sometimes you just need to start at the most likely place and work from there.
OBTW, should you decide to clean the black vent IAC, please don't post any requests for more help should it not work. Note, I am not going to tell you with absolute certaintaty it won't work because sometimes it does. However, the odds favor the results to be only temporary. Or one set of problems will be traded for another.
Good luck.
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