Running Air Conditioner Causes P0506 Code

[Mtang78]

I 1st had a problem with my U7140 tuner after installing it last Fall. Only mod is a 373 rear end - that's it. Installing the original stock tune didn't throw any codes at all. After trying several things last year, Diablo wrote a custome tune for my '05 Mustang GT. Installed it and no problems.

Fast forward to last week... battery finally went (after 5 years) and I had to have it replaced. Ever since new battery was installed, I keep getting a P0506 code. I tried clearing the codes, re-loading the 87 performance tune, re-loading the custom tune - light stayed off until I start running the air conditioner in lower idling conditions (in line through a drive through, sitting a stop light, etc.)

Any ideas anyone?? I'm at my wits end! Throttle body was replaced in 2006 under warranty.

[mikel]

No Cold Air Intake on the car?

Not sure what it could be....

http://www.obd-codes.com/p0506

[Mtang78]

No Cold Air Intake on the car?

Not sure what it could be....

http://www.obd-codes.com/p0506

Nope, nothing is different. Installed a 373 gear rear end last year and so purchased a Predator so the speedometer would read correctly. Had this same problem when we installed the Predator. Diablo wrote me a custom tune, I installed it, that fixed it. Then when I put a new battery in last week, the same problem showed up. Re-installing the custom tune (I mistakenly uploaded the 87 performance tune instead of the custom tune to the car after having the P0506 code come up after installing the new battery), it seemed fine until I was driving with the air conditioning on and was low idling / stopped in traffic / drive-through, etc. Then the engine light came on again. I should tell you that a couple of times when the light came on it said there weren't any trouble codes, I cleared the "non existent" codes, the light went off and then it was fine for awhile - until the low idling traffic makes it come back on again.

This light is driving me nuts! Please help me fix this. Thanks!

[cole]

P0506 Idle Air Control System RPM Lower Than Expected .. And yes a custom tune will need to fix this.

[Mtang78]

I have the custom tune installed. Cleared the codes again yesterday, drove 1 hour home from work (all interstate) with no light coming on and running the a/c. This morning, drove to work, but once I got into town and stop and go traffic and sitting at stop lights, the light came back on again. Any ideas? Who can fix this? Do I need Diablo to do a new custom tune? Car ran fine before changing out the battery. And before you ask, yes they checked out the alternator, etc. and everything is working fine.

[cole]

Its most likely another issue. The tune isnt going to fix the problem if its mechanical. Can you give a list of modifications done to the car? Also what rpm does the car idle at?

[Mtang78]

Its most likely another issue. The tune isnt going to fix the problem if its mechanical. Can you give a list of modifications done to the car? Also what rpm does the car idle at?

Only modification is I had a new rear end put in last year with 373 gears. No other mods. Car idles at around 600 rpm.

Should I re-install the original stock tune (my speedometer will be off)? If I do, will I lose the custom tune or will it still be in the Predator to be re-installed again?

[cole]

Do you have a copy of the custom tune on your computer still? If not you can export it from the predator to your PC if not. The reason. If the battery died then the only thing lost would be KAM (Keep Alive Memory). I would even try to raise the rpm on your custom tune by 50-100 rpm to see if you keep getting the code. Its basically telling you that the airflow is lower than what is expected by the computer. I would assume in the custom tune that the idle rpm vs airflow functions were modified without seeing it. Here is some info....


The Idle Air Control (IAC) solenoid is checked electrically for open and shorts (P1504 or P0511) and is functionally checked by monitoring the closed loop idle speed correction required to maintain the desired idle rpm. If the proper idle rpm cannot be maintained and the system has a high rpm (+100) or low rpm error (-200) greater than the malfunction threshold, an IAC malfunction is indicated. (P1506 or P0507, P1507or P0506)


So basically its stating that you have a under speed on your idle rpm.. You can try to bump up the idle 100 rpms on your custom tune and see if it helps. Or have someone look into the IAC issue on the car.