Rough idle issue

David · 07-25-2009, 04:33 PM

So ever since I traded the MR2 for the 240, my dad's owned it, and it's been sitting in his dealer. He just took it for a drive right now, and when he came back the idle was messed up. It would be at 1000rpm, and slowly rise until it gets to 1700-1800 rpm. Then it suddenly drops until it gets back to 1Krpm. The whole cycle takes about 3sec. Any idea what it might be? I can take a video clip if anyone wants.

1stgen · 08-08-2009, 11:25 PM

yup..IACV or whatever they are called..for anyone who asks this question again and again not knocking you but I t hink we shouuld get a sticky of the high idle question...

Quote:

Originally Posted by Gairloch

Unfortunately there are tons of possible causes for high idle. What you're describing goes well beyond the typical though at 2-3krpm.

I suspect that you've got a nifty neato air leak in there somewhere. Easiest way to check for leaks in the vacuum lines is to wave an unlit propane torch over them. If you find a leak the engine will rev. You can do the same thing with brake cleaner but I hate spraying that stuff on rubber parts.

If that doesn't yield anything take the intake piping off and inspect the butterfly valve in the throttle body. It could be damaged or there could be something preventing it from closing all the way. Inspect the throttle stop too to make sure it's allowing the valve to close far enough. It should be pretty tight but not actually touching the TB. The copper butterfly valve will actually dig into the aluminum neck of the TB.

If that doesn't work then while you have the intake piping off block the little hole in front of the butterfly valve. That's the ISCV (intake speed control valve) and if it's not functioning correctly can cause high idle. If you block it the idle speed should drop like it's going to stall. If it doesn't then you will want to disassemble it and clean it out thoroughly with brake cleaner.

David · 08-09-2009, 09:45 AM

I searched and read all of that. But it's not high idle. It went from 1200, then would rise to 1600, then quickly drop down to 1200, and repeat. I just adjusted the screw, and surprisingly, it was fixed.

mattdouken · 08-24-2009, 10:12 PM

you might want to check you ICV.
I know that if you set your idle high with the screw and you unplug your ICV it will idle lope.

07-25-2009, 04:33 PM	#1 (permalink)
David Banned Join Date: Jun 2007 Location: Tampa, Fl Posts: 2,621 Thanks: 120 Thanked 55 Times in 54 Posts My Google Map iTrader Rating: (4/100% )	Rough idle issue So ever since I traded the MR2 for the 240, my dad's owned it, and it's been sitting in his dealer. He just took it for a drive right now, and when he came back the idle was messed up. It would be at 1000rpm, and slowly rise until it gets to 1700-1800 rpm. Then it suddenly drops until it gets back to 1Krpm. The whole cycle takes about 3sec. Any idea what it might be? I can take a video clip if anyone wants.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

08-09-2009, 09:45 AM	#3 (permalink)
David Banned Join Date: Jun 2007 Location: Tampa, Fl Posts: 2,621 Thanks: 120 Thanked 55 Times in 54 Posts My Google Map iTrader Rating: (4/100% )	I searched and read all of that. But it's not high idle. It went from 1200, then would rise to 1600, then quickly drop down to 1200, and repeat. I just adjusted the screw, and surprisingly, it was fixed.

08-24-2009, 10:12 PM	#4 (permalink)
mattdouken Driver Of The Seven Sea's Join Date: Sep 2008 Location: Greensboro,NC Posts: 701 Thanks: 53 Thanked 29 Times in 18 Posts iTrader Rating: (9/100% )	you might want to check you ICV. I know that if you set your idle high with the screw and you unplug your ICV it will idle lope.