High Idle, but only when driving or warm., Cold, and sitting... 1000 RPM. Driving...1400 ?? Options

[MikeInMunich]

Greetings from Munich gentlemen!

As seen in the title, my car (1973 1.7 converted to 2 liter, D-Jettronic F.I.) idles at 1000 after starting and letting it sit. When I take it out in the road it quickly changes to 1400. It still idles at 1400 when stopped after the car is warm.

1) I think my AAR (auxiliary air regulator) valve isn't working at all. Disconnecting the vacuum hose, the idle shot up to about 3000 and covering it with my finger 100% it went back down to where it was before I had detached it from the AAR. So the AAR should have been OPEN as the car wasn't warm yet, but it seems to be closed 100%.

Strangely, the idle only goes up after the car is out on the road / is warm...but not even yet near normal operating temperature.

I'm thinking the AFR is leaning out under load and after the car is fully warmed up. (IMG:style_emoticons/default/idea.gif) I currently don't have AFR or CO values. I will have the CO measured cold and after warming up in a few days.

Here's another issue and question fer y'all. While looking into the bay yesterday I noticed a substantial leak at one of the fuel injectors. I didn't mess with it much (checking the seating of the seal) but after I drove the car and it was warm, I looked again and it had stopped leaking. I thought it could have something to do with temp and fuel pressure (IMG:style_emoticons/default/confused24.gif) Starting up the car cold this morning however, I checked again, and there was still no leak. Does anyone have any idea what could cause an apparently intermittent leak like this? Perhaps just fudging with it gently got a seal to sit better, but I'm skeptical about that.

Thanks for your feedback! (IMG:style_emoticons/default/beerchug.gif)

By the way, I do know about this thread on Rennlist, which is a tremendous resource:
http://members.rennlist.com/pbanders/djetparts.htm

Mike in Munich

[ClayPerrine]

Mike,

The D-Jet system will idle high when there is a vacuum leak. If your idle screw is all the way in and it still idles at 1000 rpm cold, then there is air getting into the system from somewhere. The idle would climb just like you describe as the engine warms up because it takes less air to run faster when warm.

I suggest checking the fabric covered hoses between the intake plenum and the intake runners. I had one of them split on Betty's car recently. Also get on the bird board and print a diagram of the vacuum system and check each hose to make sure it is routed and connected correctly.

Another way is to get something that makes smoke or water vapor, and let the smoke cover parts of the engine. Then look for the smoke getting sucked in someplace.

And we would be happy to look at pictures. Lots of brains here will know on sight if something is disconnected or routed wrong.


Good Luck!

[MikeInMunich]

OK! I'll post a pic in a day or two, and do a smoke test somehow and post results.

Thanks a lot! Gotta LOVE 914 World and how helpful you guys are. I personally wouldn't want to own one of these cars without this community & website! (IMG:style_emoticons/default/aktion035.gif)

M.i.M.