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[xanderdeg]

My engine is idling at 1000 - 1100 rpm when warm. I've turned the idle adjuster screw as far as I can get it yet the idle hasn't dropped below 1000rpm. I'm suspecting a vacuum leak so I'll check that out.

Is there anything else that could be causing this?

[staticsan]

Is the mixture right? Too rich and it will idle too high. A really long shot is if your AAV is stuck wide open.

IME, a vacuum leak make it idle slower. Or not at all in severe cases.

Wade.
_________________
'82 British NA - Which I think I've been very lucky with!

[joemac]

Sorry Wade, but that's just wrong.
A vacuum leak will definitely cause a high idle.
The idle adjustment on the throttle body is just a controlled vacuum leak.
So is the aux. air reg., although in conjunction with more fuel by way of the control pressure regulator (warm-up valve).

Try spraying some carburetor cleaner around the injectors while it is idling. If they're leaking, it will raise the idle while drawing in the additional hydrocarbons.
One injector at a time will pinpoint the offending culprit(s).
If no injectors are leaking, start shooting at intake hoses and their connections.
_________________
Race car: my favourite palindrome.
Porsche: my favourite race car.

[staticsan]

[Ozzie]

If the mixture has been compensated for a vacuum leak by a PO (run richer)
this will cause high idle.
This will also throw everything out when the vacuum leak is fixed.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Harm]

Something I used for testing every now and again:
Find yourself a steady downhill road that's quiet of traffic.
…In my case, rolling into town in the evening after I left the highway

Whilst driving down hill, down shift one gear
and take your foot of the gas pedal.
Listen/see if the rev counter stays stable or does fall.
The K-jetronic system in good condition will slow
down the engine and the car will drop speed.

I had numerous results over the years,
but whenever the rev counter climbed up without stepping on the gas,
it meant I had some sorting to do under the hood.
Either vacuum, mixture or timing

My 2 cents, HTH
Kind regards,
Harm.
_________________
Porsche 924 NA 1982 LY7A/A3A3 _ Greater driving pleasure never harmed anyone.

[xanderdeg]

Harm, that' some great advice!

Right now I haven't had the chance to properly check, but I get the feeling that the rev's do rise as I go down the hill, even after downshifting.

I'll be leaning out the mixture soon anyways as it seems to be running a bit rich, I'll see what happens.

[Paul]

Stop.

Find and correct any vacuum leaks
Obtain a CIS tester and check system and control pressures.
Obtain an exhaust analyzer and adjust mixture to factory specs.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[xanderdeg]

Alright will do.

Thanks for possibly saving me

Where might I obtain a CIS tester these days?

[Mudd]

I also have a high idle problem. Have you solved your high idle yet. I replaced all vacuum lines, tested the AAV, replaced the injector seals and still high idle. I was hoping to follow this topic to get answers for my problem, but it kind of just stopped.
_________________
1978 924
1987 944

[xanderdeg]

My idle seems to have fixed itself with minimal tinkering on my part...

It was probably just the sudden change in weather that changed the cars idle characteristics (35 year old mech fuel injection will do that...)

Try making your own thread, responses will be specific to your problem and most likely more helpful!

Best of luck

[curtisr]

Xander,

Glad things are better.

I was going to ask what the idle was when the AC is running.

When my AC is on, the rpm is ~ 800. When it's not on, 1100. I'm not suggesting that my results are where it should be, just sayin'...
_________________
World's worst welder.