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Join Date: Jul 1998
Location: Elgin, Illinois
Posts: 76
Idle Speed

I hope you can give me some advise on this problem. When I start the car and the engine is cold, it idles at a constant 2000 rpm. I drive about three miles, and come to a red light, the car idle drops to almost zero rpm then up to 1200 rpm, then down to almost zero and up to 1200. It repeats this down/up/down/up until I drive a little further, and the engine warms up. It then idles most of the time at 1200, however, there are times when the idle returns to 2000, and I have to tap the gas pedal, so that the idle drops to 1200. My questions are: 1. Is the reason for the down/up/down idle is the "brain" searching for the correct oxygen/fuel mixture? 2. Why do I have to tap the gas pedal to drop down the idle? The gas pedal moves freely and does not appear to be stuck, and the pivot point for the cable at the engine end for the cable moves freely and is very clean.
I have a '73 1.7L.
THANK YOU for any assistance with this problem.

Regards,
Keith
Old 10-27-1999, 06:06 PM
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Join Date: Dec 1969
Location: chula vista ca usa
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Probably a vacuum leak. Check ALL hoses, the manifold boots, throttle base gasket, inlet plenum for cracks. Any hoses that are hard should be replaced or if there is enough room, cut a little off the end. Check the base gasket on the vent can to make sure there is a tight seal and make sure the PCV valve is clean and free. Last of all make sure the multiple connector where the line from the PCV valve connects to the inlet plenum has no cracks. Good luck.

[This message has been edited by john rogers (edited 10-28-1999).]
Old 10-28-1999, 06:17 AM
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The hunting is a classic vacuum leak sign, but doens't normally change that much warm to cold so you might have two things going on.

I also had problems with hunting at idle to the point where it would drop so low it would die when I put the clutch in at a stoplight. I was informed a worn out clutch can also cause that problem and I don't know which fixed it because I replaced the manifold hoses and the clutch at the same time. End result - no more hunting so I'm happy.

Good luck.
Old 10-28-1999, 08:05 AM
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Your aux air regulator may be dead or not plugged in. Check to make sure the wire coming out of the bottom is plugged in. Make sure you can blow through it when the engine is cold. Make sure you can't blow through it after the engine is warm. (5-10 minutes of driving.)

Hunting like that usually indicates a lean mixture. It can be caused by vacc leaks, though those often just cause a high idle on a D-jet car. You might try tweaking the knob on the ECU clockwise. Count the number of "clicks" to make sure you can get back to where you were, though!

Check Kjell Nelin's D-jet article on the 914 Fan Page. http://www.914fan.net under Tech Articles. That will help you track down a lean mixture, if that is in fact what is wrong.

--DD
Old 10-28-1999, 09:12 PM
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Join Date: Jul 1998
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Dear John, Ascaris, and Dave,
Thank you all for your replys - you are great. I found the problem - vacuum leak. I had a stacked vacuum elbow connected to the air intake distributor with no hose attached to the top, or small, connector. I have the proper connector on order, and should have the problem resolved next week.
John, you gave me alot of help when I replaced my fuel lines in the center tunnel. And Dave, you helped me fix my odometer that would'nt always work. THANKS AGAIN for your help.
Best Regards,
Keith
Old 11-03-1999, 12:25 PM
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You're welcome for sure. The elbow you are talking about is some sort of German plastic I think, on our stock 914 it was and it cracked so I made one from regular small brass pipe fittings and it should last forever? I also used a longer piece of good German double thickness hose and moved the fitting up higher so I can actually get to it. Good luck.
Old 11-03-1999, 02:09 PM
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