From: Wally Plumley [wplumley@bellsouth.net] Sent: Saturday, July 14, 2001 8:42 AM To: 928 Subject: [928] RE: vacuum line to idle stablizer At 08:30 PM 7/13/01, Greg Klanderman wrote: >Jim, > >Thanks, that's what I was figuring, though I've seen numerous posts >and OC tips regarding the vacuum line to the stabilizer. > The unit in question, which goes by a number of aliases (idle stabilizer, rotary idle actuator, idle speed actuator), is the ECU-controlled servo that controls the idle speed on S4 - up cars. It does this by regulating the flow of air from a fitting before the throttle to a fitting on the intake manifold after the throttle. Thus, the idle actuator or idle stabilizer acts as a computer-controlled bypass valve around the throttle, controlling the idle speed. The actuator valve sometimes begins to stick due to crud build-up. The clearest illustration is on page 24-216 in the shop manual. There is a fitting in the side of the large tube that connects the MAF sensor to the throttle body. Air that flows from this fitting thus has passed thru the MAF sensor (and is "measured air"), but has not passed thru the throttle (and is not "controlled air"). There is a Tee in the air hose attached to this fitting. One leg of the Tee runs to the inlet side of the idle actuator, furnishing the bypass air to control the idle speed. The other leg of the Tee runs to the vacuum ejector, the slant-Tee vacuum fitting located on the right side of the intake, near the throttle cable quadrant. (This fitting is a vacuum booster, utilizing air flow from the Tee and large inlet tube into the intake manifold to furnish boosted vacuum to the vacuum brake booster.) There are three lines on this slant-Tee fitting. One runs to the vacuum brake booster; one runs to the intake manifold plenum; and one runs under the manifold. If you disconnect the input tube (the one that runs under the manifold to the Tee) and block the opening in the fitting, then spray a solvent, such as WD40, into the tube running under the manifold, the air flow into the idle actuator will carry some of the solvent into the valve section of the actuator, where it may or may not remove some of the crud and reduce the sticking. If you are desperate enough, you can pull the air filter housing and MAF sensor off, clamp the inlet hose shut at the slant-Tee, and spray solvent into the fitting in the large inlet tube with the engine idling. This will get a heavier dosage of solvent to the idle actuator valve mechanism. Wally Plumley 928 Specialists From: TommyEst@aol.com [mailto:TommyEst@aol.com] Sent: Sunday, April 07, 2002 11:21 PM To: 928 Subject: [928] Idle Stabilizer blues cured My idle stabilizer has been acting up for months, I had to heel and toe to keep the idle up when coming to a stop. Once stopped it would generally hold, but would jump up and down. I tried spraying WD40 and Boeshield T-9 into the tube leading to the stabilizer with very little effect. I was doing this while the car was stopped and the engine was not running. I would spray until it was backing up out of the tube, stop, reconnect the tube, start up and drive some more. Today I got the bright idea to use the sprays while the engine was idling. I did this for about 5 minutes alternating sprays, hooked the tube back up and when for a drive. SUCCESS!!!!!!!!! Problem totally solved. The idle drops down cleanly, when driving and stays stready. It may even solve a hot starting problem. I'll know more in the future. There may have been a note to do the spraying while the car is idling, but if so I missed it. So for those of you having similar problems, take note. Tommy Estridge Back to normal 88 5 spd. black/linen SOCAL 928 From: Jay Gary Wellwood [mailto:wellwood@cswnet.com] Sent: Saturday, May 04, 2002 11:10 PM To: 928 Subject: [928] Idle Stabilzer Sticking? Try this... Okay Gang- Besides the WD-40 trick, check to see if your Idle Stabilizer is actually working on an 87+ models as follows- Disconnect the LH wiring harness from the LH Brain, Use a short piece of wire to jumper contacts 17 to 21 (by rotating the LH plug in such that the locking ear piece is pointed left with the locking handle pointing right, the bottom right most point is #1). Using a longer piece of wire, insert it into point #33. Route this to the engine bay so you'll be able to listen to the Idle Stabilzer. Touch the free end to a bolt associated with the engine brace. You should here the Idle Stabilizer swing full open. Remove the wire and you should here a prompt 'thunk' signifying the stop position. This should help you determine if you have a stuck/sticky Idle Stablizer (or help free it up using the WD-40 trick). hth- Jay 87 S4 Auto