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datatrain · Posted: Sat Jun 07, 2008 12:28 pm Post subject: Unable to slow idle speeed.

I've been asking various question here for the past couple of weeks. Now I'm not sure I'm winning or losing.

I had problems getting the air inlet boots to fit properly and that's now okay. But after getting it all together the idle speed is above 1150 rpm. Even with the idle screw fully closed it's the same. Also I'm getting severe pinging or rattling under load.

I checked all the vacuum connections and there is nothing obvious. But I did have a broken vac. line on the spark advance control a couple of days ago before I started this new project to clean everything up.

Not sure it's relevant but last week put on a new oil filler cap. The old one had a torn gasket and dribbled a trace of oil for 14 years so obviously the EGR system wasn't working perfectly either. I now notice a bit of blue/grey smoke in the exhaust. Smoke which I don't recall before

I'm wondering if the engine had so many out of tune items but it ran well that now I'm fixing things the problems are multiplying.

About 15000 miles back I had new rings and bearings and the valves were quite good so that should not be a problem.

I was driving the car up to 2 days ago and enjoying it.

I'm not quite sure how to get the idle back to 950 any ideas ?

Thnx
DAve

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I would think that if you can fully close the idle screw, you have got to be sucking air somewhere. Any hose that has not been replaced is probally due anyway.

Does it do the same hot or cold?

Shawn
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1980 931
That's thirty minutes away. I'll be there in ten.

Smoothie · Posted: Sat Jun 07, 2008 12:55 pm Post subject:

Two items, the AAV and the decel valve bypass the throttle, soooo if either of them are stuck open, idle speed will be uncontrollably high.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

leadfoot · Posted: Sat Jun 07, 2008 1:24 pm Post subject:

My guess is your timing is off. Maybe it was advanced to compensate for the leaking air or it has slipped due to a loose lock down plate on the side of the dissy.
Confirm your timing is stock with a timing light on the bell housing inspection hole.
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

datatrain · Posted: Sat Jun 07, 2008 2:56 pm Post subject: Answers to reply's

It does the same hot or cold.

I'll check the decel valve and aux air regulator.

Changing hoses looks to be in my immediate future.

Dist. is tight and could not move.

As I said, it ran fine 2 days ago.

Thnx

DAve

968rz · Joined: 21 Aug 2006 Posts: 537 Location: S. E. Wisconsin

I would check for vac leaks first then check the timing; too much advance would cause this and since you stated the dist is tight and unmoved I would check that the belt didn't jump some how.

And before you think I'm off

, Last year my 968 timing belt jumped forward 2 teeth

. Never did figure how (I blame wife as she was last to drive it

).
_________________
Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

Ozzie · Posted: Sun Jun 08, 2008 1:22 am Post subject:

Youre too far advanced. like 20deg .
Had the same problem with another car.
Get a timing light on it pronto and back to spec.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

You may want to check your throttle stop screw. If the car was running bad, sometimes POs use it to keep the car idling, even though it isn't supposed to be adjusted.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

+1 on what Rasta mentioned. Also, the o ring for the idle adjustment screw hs been known to deteriorate and cause a high idle.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

I have a question

If it is a timing problem, would you still be able to completly close the idle ( bypass) screw and not have an effect?

Shawn
_________________
1980 931
That's thirty minutes away. I'll be there in ten.

968rz · Joined: 21 Aug 2006 Posts: 537 Location: S. E. Wisconsin

Yes, the idle screw doesn't control all the air, it just routes some past the closed butterflies.
_________________
Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

tom! · Joined: 23 Jan 2008 Posts: 66 Location: Central NL

My very high idle went down to normal regions after the CO was adjusted back from 3.5% to 1.3%.
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1980 924 2.0, Saturn metallic