Idle creeping again please help no more ideas

[ertech]

Hi all.
have been searching on this board and others but did not find the same symptoms.

I have a recurring problem on my 89 930 that no one found the solution .
the car drives great when cold the idle is 13-1400 than goes down to 850-900 .
if I drive it for a while and the engine is hot when i get to a light and stop . the idle will be OK and than start to creep up by itself to 14-1500rpm . I pinch the AAR hose and no difference . the only thing that will help is if i put the car in gear and put load on the engine ,it goes down for a few seconds and goes back up.I also checked the vacuums and the pedal linkage ..the AAr also functions . I tOKe the AAV off last night to test on a bench by applying vacuum to it and it does keep vacuum and the bypass works.
My 89 has what loOKs like a sensor at the throttle body with a electrical plug to it. what does this do ?and can this be my problem ?how do i test it and should I unplug it?
any idea would be great.
Thanks so much
Erick Marciano

[beepbeep]

Have you checked for leaks? Phenolic intake spacers and their gaskets? Auxillary air valve (throttle bypass)? Start blocking off stuff after throttle that can possibly suck air and see if idle changes...there are plethora of hoses which can leak. Virtually every gasket, grommet and hose from throttle to head can cause this.

[ertech]

would the spacer expand when hot and cause the leak?the AAV works on the bench it I delete it should I block of all the ports to it or vent the one coming into it?
I have way to many questions sorry
thnaks

[beepbeep]

There are additional components which can cause high idle. There is a brass cylinder (throttle bypass valve) which bypasses the throttle. check it's hoses for leak.



The easiest way to find leaks is to pressurize everything south of CIS and listen to leaks. On the top of this you'll need to check for leaks in stuff which can leak "internally" across the throttle.

1. Check for general leaks (by pressurizing whole air system south of CIS).
2. Check AAR and throttle bypass valve for internal leaks.
3. Check that throttle is closing fully.

[mooney265]

[QUOTE=beepbeep;4890626]

1. Check for general leaks (by pressurizing whole air system south of CIS).
QUOTE]


Q: How would you recommend "pressurizing whole air system south of CIS?"

Thanks!

[beepbeep]

[QUOTE=mooney265;4890900]

Originally Posted by beepbeep

1. Check for general leaks (by pressurizing whole air system south of CIS).
QUOTE]


Q: How would you recommend "pressurizing whole air system south of CIS?"

Thanks!

Take off the hose going to CIS, turn it upwards and jam suitable disc with a nipple. Pressurize. I bet you will hear hissing sound on 90% of 930 around. Chase the leaks, repeat. (thus usually ends with order for new injector stacks and/or gaskets).

[full quack]

Mine had many of the same problems, had Brian Leask rebuild my WUR. All my problems went away. Been almost a year now since the WUR rebuild, and none of the problems have returned.
My .02 worth
Mark

[mooney265]

[QUOTE=beepbeep;4890989]

Originally Posted by mooney265

Take off the hose going to CIS, turn it upwards and jam suitable disc with a nipple. Pressurize. I bet you will hear hissing sound on 90% of 930 around. Chase the leaks, repeat. (thus usually ends with order for new injector stacks and/or gaskets).

Goron, that's a great idea [I'm sure you've heard that before]. anyways, I get it - - I'll just need to create the "plunger/plug" tool...

Thanks

[ertech]

Just put the car back together and I removed the aav .love the way the rev go back down during shifting .the car runs great. Have to wait till monday to see in
trafic .I was told to check the dist vacuum switch and the wur.
Hope it was the aav
thanks

[ertech]

Just put the car back together and I removed the aav .love the way the rev go back down during shifting .the car runs great. Have to wait till monday to see in
trafic .I was told to check the dist vacuum switch and the wur.
Hope it was the aav
thanks

[mooney265]

yes, i'm so much more comfortable shifting without the revs "hanging" - - it was really a bummer, before!!

i no longer feel the car will "over-rev" when I shift at higher rpm's...