Hello everyone. My car was recently idling and dying at stop signs and red lights a few weeks ago; and sometimes would not even stay running. My friend ran a test with a handheld computer and noticed that I need a new Idle Air Control (IAC) Valve. I have a 2.4 Convertible, so that piece costs about 300.00 at AutoZone. My good friend "ebay.com" gave it to me for 75.00 lol
So my friend installed it for me but now it's running very rough. My throttle body is very clean. The car now stays running and normal RPM (Between 5000 and 2000 RPM) I drove it and does not die anymore. But it's just running really rough and my engine shakes like crazy. My engine light came on while testing driving it and had it scan and the guy told me to check the "timing on the car"... What the HECK DOES THAT MEAN??
Please help!!!!!!

Thank u

Check timing, means exactly that. Check your timing marks on the cam gear in relation to the crank gear. If the timing is out of sync, check your cam/crank sensors, or anything else the specific trouble code suggests you inspect for possible faults.

Keep in mind this is predominantly a 420a forum, with less support for the 4g6X platforms.

We will help where we can, but you might have better support on a dedicated forum for your platform.

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2012 2500HD LML

I can't believe (ok, maybe I can) that Autozone charges close to dealer prices on the IAC for the 4G6 engines (I paid $330). When I had my '93 GS, I went with the dealer IAC, since there was a revision to the design to make it more reliable.
Anyway, test the IAC you put in for peace of mind. I've had too many turbo DSM guys tell me horror stories regarding aftermarket IACs. I believe it could be that alot of aftermarket companies base their IACs off of Mitsubishi's original design, not the revised one. Plus, if there's an issue that arose once you changed the IAC that wasn't there before, chances are the IAC you installed could be defective.
Another possibility is that the plug or wire for the cam sensor could have been loosened during the IAC replacement. That would most definately cause issues, since the ECU would basically be left to 'guess' when to fire the injectors and spark plugs. Your timing could be fine (especially if it didn't run rough before), but the ECU might not know that if the signal to the cam sensor has been severed.
While I'm still thinking about it, what is the condition of the idle set screw? Those tend to get messed up, since they're made of soft white plastic. The threads and/or o-ring could be shot. And they're cheap to replace.
Hope this helps.

My guess is that you bumped or messed up the CPS that is in the same location. Your IAC sensor has nothing to do with timing, but the CPS does. It's also possible your CPS crapped out too.

did you try putting the old IAC back in to see if you still had the problem?

1999 Eclipse GST 4G63