Adjusting the Idle/ A.C vibrations

[07turbocharged]

I'm pretty new with import engines, when my A.C. is on it pretty much runs at like 400 RPM, how do i adjust it to a higher RPM? is there a little skrew somewhere or is it just computerized? Also when the A.C is on, my car vibrates really bad....any suggestions on what it is? a bad pully or something? thanks for future help!

[navylife59]

Assuming that the vibration is at that low idle, it is caused by the load of the A/C at that low RPM. If you could adjust up your idle, it would smooth out. If the vibration persists at higher RPM, it could be a bad serpentine belt, bad electromagnetic clutch, over pressurized system (freon), or worse, a damaged compressor.

Idle is controlled by the ECM via the IAC (Idle-Air Control) valve on the TB. Assuming that you MAF is still in control of your air measurements, the intake piping maybe skewing the MAF data causing improper control of the IAC. Need to know more about your setup.

[Cameronbic]

I'm actually having the same issue. My car, until fairly recently, idled at approx 900 RPM. Now it idles at around 700 (or less). With the A/C on, or if the fans behind the radiator turn on, the RMP dips to 4/500 the engine vibrates tremendously. It's there at normal idle, but not nearly as bad. I realize that the extra strain on the engine is causing the vibration, but this is being caused by a low idle. The really weird thing is that if I am coasting, even for a long time, the idle stays at 900+ RPM, it's not until I come to a stop that idle drops.
I actually took it to the dealership today and they diagnosed it as a dirty fuel system. They ran some sort of cleaner through it and pronounced it cured. Before I left the lot, I gave it a minute to warm up, at which time it began vibrating again and idling low. They did essentially the same thing but with what he called a 'more premium' cleaner going "all the way through the rail", still the same. No codes from the computer, so he says everything checks out. They acknowledge that there is a problem, but everyone seems at a loss.
Stock '06, only 25k miles on it. New plugs, only ever had 92+ octane gas in it. Any ideas?

[Sciontc06]

I am having the same issue also. My Cheach engine light came on and the only code it is showing is MAF. I am not sure what to do to fix it. i have a friend that has a garage and all he deals in is TC's and he had no clue. i am also having idleing issues when i pull up to a stop light me RPM's jump around from sometimes as high as 2500 to 750. anyone have any ideas

[navylife59]

It is your intake. A gross vacuum leak would cause a high or even surging idle (intermitten leak via a valve, etc) but it would not throw a DTC for a MAF. Which code is it? Do you have a custom or aftermarket intake? If so, please describe in detail.

[Flint Mica tC]

mine idles a little high with vibration too, I have a HPS short ram intake, was thinking about throwing on an engine dampner. Think that would take care of it or do you think there is a source causing the bad vibrations?

[navylife59]

An engine dampener is designed to limit engine movement during hard acceleration (high torque loads). This causes more engine vibrations to transfer into the frame rails of the Unibody construction. Any intakes that alter airflow from the OEM intake risk the engine running smoothly. MAF tuning/timing is very critical.