05 mustang idle problem pls help!

[xtimesofgrace]

hey guys im new to the forum anyways i have a 2005 mustang and it has been a great car. the car has ran absolutely flawless since i've had it. i recently changed the battery in the car and ever since i changed the car will not idle right when the ac is on. we reconnected the battery correctly and did everything that the owners manual told us to do (drive the car and let the computer reset itself). when i was driving it today the check engine light came on so i took it to autozone and the guy told me it was the idle control system (he didnt give me the code he just told me what it was) he said he couldnt reset the computer but he could reset the light. i am wondering if you guys can let me know what the problem is, ive driving the car about 65 miles today and the idle still fluctuates when the ac is on, when the ac is off the car idles perfectly normal (around 750 rpm)

 

[jonbacon]

Whats the CCA for the battery... the rating of amps..for the new one you put in

 

[bigb427]

Did you read this thread: http://www.stangnet.com/mustang-forums/845443-car-idle-off-after-replacing-battery.html

The problem is your throttle body. It is either sludged up and needs cleaned and/or it has excessive wear. Disconnecting the battery clears the computers adaptive strategy for idle. It learned how to cope with the throttle body over many, many miles and now has lost that information. This concern is worse on higher mileage cars. The throttle body may need replaced, but I would try cleaning it 1st. Be sure to disconnect the battery again for about 10 minutes before starting it, after cleaning the throttle body.

 

[xtimesofgrace]

Whats the CCA for the battery... the rating of amps..for the new one you put in

CCA is 590. the car also has 41k miles give or take a few. like i said the car ran perfect when i got it

 

[xtimesofgrace]

Did you read this thread: http://www.stangnet.com/mustang-forums/845443-car-idle-off-after-replacing-battery.html

The problem is your throttle body. It is either sludged up and needs cleaned and/or it has excessive wear. Disconnecting the battery clears the computers adaptive strategy for idle. It learned how to cope with the throttle body over many, many miles and now has lost that information. This concern is worse on higher mileage cars. The throttle body may need replaced, but I would try cleaning it 1st. Be sure to disconnect the battery again for about 10 minutes before starting it, after cleaning the throttle body.

i will try cleaning it but i dont think it needs to be replaced 41k isnt THAT many miles haha


btw thank your for the responses guys.

 

[xtimesofgrace]

going to try cleaning throttle body today ill keep you updated.

 

[durtyd929]

I've been having a similar issue in my 05 GT(61,000 miles), I also get a low or rough idle. I pulled the P 0506 DTC(low idle present) with my tuner, every time I clear the code, the problem remains and the check engine light returns. I've done some research and this problem may be caused by restricted airflow through the throttle body, vacuum leak, faulty EGR valve, or potentially something else. I'm gonna try cleaning my throttle body and replacing the EGR valve, I'll let you know what happens. If there's anyone else who's had a similar issue, please advise on your experience and or any possible remedies.

 

[durtyd929]

Hmmm, scratch that, apparently the newer 4.6's don't have EGR valves. Back to square one. Would still appreciate any info

 

[bigb427]

Restricted airflow or a vacuum leak would result in different codes being present from the P0506 you have. Your concern is also most likely the throttle body itself.
All Ford engines equipped with variable cam timing in any form do not use an EGR valve, so you are correct, your car does not have one.
If there is too much backlash in the throttle body mechanism due to wear or a manufacturing defect this can cause the problem you are having. An excessively dirty throttle body can also cause it. Try cleaning it, if that doesn't work you are going the have to replace the throttle body.

 

[durtyd929]

Thanks for your input, I bought a can of throttle body cleaner and sprayed the throttle bodies thoroughly. I put everything back together and started the car, no more rough or low idle, feels very smooth and pulls nicely. Looks like the throttle bodies were in need of a good cleaning.