So my idle is all over the place...

Somtimes its even at around 1000
Then it may fluctuate between 1000 and 1500-1800
Then sometimes its stays at around 2000

If I'm sitting at high idle at a light I can 'force' the engine down to 1000 with the clutch and brake and it may stay there.....or not

So my question is: Barring vacuum leaks, How do I know if the MPS is faulty? or the AAR? or CHT? or whatever else might cause this.

Note: All new hoses, all new gaskets, same old FI parts

Good website to help troubleshoot Djet problems is Brad Anders site: http://members.rennlist.com/pbanders/DJetParts.htm

You need to pull a vacumm on the MPS to test it, do a search here for details.

Kev

you're going to ruin your clutch. then it's a flywheel, pressure plate, throwout bearing, assorted other items...then "while you're in there"... stop doing that.

k

its got to be a vacuum leak or the AAR valve is sticking

Its not like I'm riding the clutch to keep it there. Just giving it a little shove to get the idle down, no more than starting on a hill from 1st. Then the clutch comes off or on I guess.

I had similar symptoms. The problem was the timing wasn't retarding at idle reliably. The solution was cleaning / lubing the the distributor advance plates and replacing the vacuum canister (wouldn't hold a vacuum).

It turned out to be stuck AAR

I have a couple to sell if you need one.

I have followed this thread with interest as my 73 does exactly the same thing. How much for a working AAR valve? I'd like to get another and see if it fixes my idle issues.

Gary

I just took it out turned it over and flushed it with carb cleaner.

I had three and they all had the casing cracked on the wire where it comes out of the AAR but they all worked ok with a dose of carb cleaner.

The connector from the AAR to the harness CHT is a little suspect though

Click to view attachment

Uh, there is no connector from the AAR to the CHT. They don't even plug into the same wiring harness! The AAR plugs into the "engine harness", the one with the coil wires and such, while the CHT plugs into the FI wiring harness that goes to the ECU and injectors and so on.

--DD

When my car did this it was stripped CHT threads so it would loose ground and then get it again.

Yeah Dave, I just looked at the pic and thought maybe thats the CHT

I'm no guru on this stuff. I need to relearn everything each time I open the lid

You running points or ignitor or ??? I had a problem where my idle would settle at various RPM. Turns out, my Ignitor 1 module was rubbing the inside of my distributor cap. Leaned it over enough that the inboard corner of the ignitor machined a nice groove around the OD of the rotor. So what was happenning is the vacuum advance would advance the plate, and there was enough friction to hold it there- sometimes. So sometimes my idle was maybe 1200-1500, but sometimes it dropped back to 800. If I blipped the throttle, I could sometimes get it to dislodge and go back to where it belonged.

My Ignitor 1 is circa 1986. For years I used aftermarket caps, with no problem. Finally I switched to a Bosch cap, and voila, interference.

I ground the corner of the Ignitor module down, and relieved the inside of the Bosch cap with a drum sander on my dremel tool- cuts like butter. No more binding.

Haven't seen a similar problem posted here yet. Just another idea.

Jim

What do I win???