Date: 8 Mar 2004 03:00:49 -0800 From: lars_johannessennospamail.com (Lars Johannessen) Subject: Re: Engine rotational speed
"SAABurger" <furnyburgernospamorld.com> wrote in message news:<ff02c.823$re1.778nospamfe1-win>... > "Dave Hinz" <davehinznospamcop.net> wrote in message > news:c29tmb$1q6ohv$2nospam34476.news.uni-berlin.de... > > On 5 Mar 2004 00:40:33 -0800, Lars Johannessen > <lars_johannessennospamail.com> wrote: > > > Dave Hinz <davehinznospamcop.net> wrote in message > news:<c278vd$1qki8e$2nospam34476.news.uni-berlin.de>... > > >> > > >> Is the throttle closing completely, or is something (the dashpot maybe) > > >> keeping it from closing? > > >> Do you hear any air leaks or see any loose hoses? > > > > > > Thanks for the reply, and yes I have cleaned the trottle house (not > > > sure of the name here), and everything around it (where the air comes > > > in). And when I look at it and the motor is running; everything seems > > > ok to me. > > > > Has your car, in the past, had a "surging" in the idle speed, where > > it goes up and down a lot? There is a valve which controls idle speed, > > I wonder if it might be stuck open? Have you had any problems like that? > > I think the valve Dave is referring to is the Idle Air Control (IAC) valve. > This is the controlled element in a servo system which actively controls > engine idle speed to maintain it at one of several "set-points" (to use a > control system term), depending on several factors. The other main elements > of the servo system are the Electronic Control Unit (ECU) and measures of > (primarily) rpm, temperature and throttle position. > > IACs are prone to becoming sticky and hence not controlling properly. In > particular they are prone to sticking fully open or fully closed, due to the > way they work (oscillating shuttle). I had both cases before I eventually > fixed mine. The "open" case gave idle revs in the range you describe > (2000-3000 rpm). Before it sticks completely an IAC will generally give a > loud metronomic 'CLICK' of about 3 Hz at tickover. It may do this for weeks > or months before eventually deciding to stick in one position or the other. > Spontaneous recovery is also possible, though it will be a matter of time > before the problem reappears. > > Ultimately, you may need to replace the IAC valve but not before trying to > unstick it. I recommend INJECTOR CLEANER, which is designed to dissolve the > same sticky residue that is affecting your IAC valve. This is by far the > simplest approach, as disassembly/reassembly is minimal. > > You can buy injector cleaner from most high street automotive stores or > motor factors. Simply use it as per the instructions on the can (typically > spray into the air intake with filter removed). From my experience (SAAB and > other makes) you will need to spray significantly more liberally than the > instructions indicate. > > NOTE: Terminology and design details may differ depending on the particular > type/brand of fuel injection system fitted. Thanks again Dave and furnyburger. I will check this things out, buy a injector cleaner and try to clean and fasten those elements around the trottle valve. And yes Dave, I think I had the problem you mentioned. furnyburger; I will follow all you're suggestions here to see if i helps. When I searched through the nospam site, I also find this (http://www.nospam.com/techhelp/c900/throttle_valve.php); very helpful. Thanks again. Regards Lars.
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