High rev when engine is warm

a-dougk1 · 10-29-2004, 11:39 AM

Just recently my '79 has begun idling at 2200 rpm when it is started with the engine warm. It takes several minutes for the rpms to settle down to the normal 800 rpm I would expect. The engine starts fine when cold and idles at 800 rpm.

Any ideas on what is causing this? (Translation - what do I need to fix?)

Doug

konish · 10-29-2004, 11:45 AM

Maybe your AAV or AAR (can never remember which is which, but it controls the idle control circuit for cold start) is sticking open a little longer than normal....pull it and run a test to see if it's closing when it should. I probbaly would not worry about it due to the colder temps...

R/
Dustin

Paulporsche · 10-29-2004, 12:43 PM

Try checking for air leaks from the airbox to the intake runners, the vacuum hoses, the decel valve, the airbox popoff valve, your mixture setting, your distributor. Make sure your sensor plate operates freely. Check your warm control pressure.

I don't know if you have an O2 sensor or frequency valve on 79 turbos, but if you do you should check there too.

Also make sure your throttle linkage is not hanging up somewhere.

Randy Webb · 10-29-2004, 02:27 PM

This is just one of the many posts that reminds me how much I hate the CIS system....

Anyway - good luck.

a-dougk1 · 10-29-2004, 03:44 PM

Just to be a little more clear (and maybe pinpoint the problem), what happens is the car starts cold correctly (idling at about 800 rpm). Then I drive around for a while and the engine temperature gets to normal operating temperature. Now let's say I shut the engine off and go into the book store for 15 minutes. When I come back out and start the engine, it idles at about 2200 rpm, blasting away while everyone looks at me in disgust and disapproval at my apparent wanton display of machismo.

Does that clarify the problem? (The mechanical problem, not the psychological one

Doug

cab83_750 · 10-30-2004, 12:32 PM

Quote:

Originally posted by a-dougk1
it idles at about 2200 rpm, blasting away while everyone looks at me in disgust and disapproval at my apparent wanton display of machismo.

Does that clarify the problem? (The mechanical problem, not the psychological one

Doug

1. Just make sure you stay away from cantinas where gangs/hard-core bikers hang out. Then you are definitely in trouble!!! har! har! har!

2. At least, you are not driving in front of 20+bikers and your horn gets stuck, and it starts blasting away!!! har! har! har!

Sorry, I just had to slip in some funny thoughts! Anyway, I have an SC and my idle goes up in the winter time. However, it does not go past 1400 rpm. This does not happen if I park it in the garage. I'll let others chime in.

Type911 · 10-30-2004, 12:48 PM

Doug,

Same symptoms on my SC...turned out to be a bad decel valve.

autobonrun · autobonrun's Garage

I take the lazy man's way out and cut my A/C on. Loads it down right back to a reasonable level. I'll get to it one day but in the meantime, this reduces the idle and keeps your A/C seals lubricated during the off season.

a-dougk1 · 10-30-2004, 07:25 PM

Quote:

I take the lazy man's way out and cut my A/C on. Loads it down right back to a reasonable level. I'll get to it one day but in the meantime, this reduces the idle and keeps your A/C seals lubricated during the off season.

Wish I could do the same, but the PO took out part of the A/C system, specifically the compressor. If you know someone who wants to sell a '78-'79 Turbo York compressor cheap, let me know (I'm currently suffering from middle-class poverty). It's the one that sits up (not on its side), and the hoses go over the top of the compressor to connect.

Doug

Paulporsche · 10-30-2004, 07:42 PM

Have you checked what Konish and I have suggested?

a-dougk1 · 10-31-2004, 03:35 PM

I took the car out this afternoon to warm it up. With the trusty Bentley manual in hand, I began looking for some of the most likely causes of the warm idle problem. Much to my surprise, I couldn't find the AAV, AAR, decel valve (the 79 doesn't have an 02 censor or freqency valve), at least not in the locations indicated by the Bentley manual. They're either not used in the Turbo (unlikely), or they're hidden in some hard to find location. I spent about 45 minutes with a flashlight poking around in the engine compartment trying to find anything that looked anything like the parts shown in the Bentley manual to no avail.

I'm going to see if I can borrow a set of Turbo workshop manuals from a friend, and I'll let you know if I can find any of these parts (next weekend's project).

Doug