High Idle
 

Finally got the engine back in and the P-car running. Everything is great except for a high idle. Since it's a DME car I really don't want to mess with anything. I was planning on having the mixture set soon anyway, but I'd like to get this sorted out first. Ideas?

John

Gently rap on the ISV with a block of wood...it might be a hung-up Idle stabilizer valve. ...first attempt at fix is to demount and squirt cleaner through...
---Wil Ferch

John, the official procedure is to first set the base idle with B and C jumpered, it's that round relay rubber socket on the left rear engine bay panel behind the removable cover. This will stop the function of the idle valve. Then with the engine at normal running temp, using a 7mm deep socket (or a flathead screwdriver for the earlier cars), turn the idle adjustment screw clockwise to reduce the base speed, and counter clockwise to raise it. The 84-86 spec is 800 rpm, the 87-89 spec is 880 rpm. It you have an 87 chip in your 84-86 dme, set it to 880 rpm. Remove the wire from the test jack, recheck adjustments, and correct if necessary.


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I once got the same hi idle after the engine drop. It was as simple as the throttle linkage getting stuck because I used a slightly longer bolt to re attach the cruise control cable back on to the throttle plate. THe longer bolt prevented the throttle from returning to the rest position.

It could be your mixture, but it could be something as simple as a longer bolt.

I know that a CIS car will do this with a slight vacuum leak. Unsure about a DME car though. Just a thought.

Worked perfect, thanks Steve.

John

Glad to help ;)

Ok. Idle has come down to where it should be and car runs great. However, when cold and I go to start it is a struggle. Previously I would just turn the key and it would fire and idle perfect. Now when I turn the key it starts and dies. I have to feather the gas to get it to run. It will run, but the revs will hunt a lot and I need to keep the gas on for 20 seconds in order for it to idle on its own. Are these problems related?
CAr has new O2 sensor and new style, though not brand new, head temp sensor. I shorted pins as described when adjusting idle.

John

It's may turned down too much and not getting enough air - turn the idle screw out about a half turn at a time and see if it improves.

Hello Steve W
Is the procedure the same for the a 1987 930 Turbo?
thanks in advance

ALz, don't think so as the 930s are CIS and mechanically controlled.

Is it possible the problem was in your linkage, but you adjusted the idle? Now the idle's too low, but the linkage has gone back to normal, and the car is killing itself? My linkage on my T was screwy after my drop, it occasionally will hang up around 2000 RPM, if I blip the gas, or pull the pedal back with my hand, the idle returns to normal. I think I may have slightly bent it on the transmission bell crank, but I need to get the car running again to troubleshoot. Good luck.

1whpddoggie,
Look under the car at the transmission bellcrank and make sure that the throttle linkage isn't contacting the e-brake cable. You may have to pull the e-brake cable up and use a zip-tie. That little cloth support doesn't do much good after 30-odd years...

Control throttle plate ajustament(thorttle plte to throttle housing is in 0.4mm).
Too controler adjust throttler linkage.The play is 1 to 2mm.

Regards
Luis