Searches for idle when cold
 

I have a great running 3.6 transplant in my '77. The only problem I've been having is that when the engine is first started,(cold), it will search for proper idle. It will idle up and down in a range of about 4 RPM's. Any suggestions?
Tom

Sounds like it is running rich. The surging is a sign of this.

any ideas, anyone, Kevin

My 3.2 does this if the ambient temperature is below 45 degrees F. I don't drive it that much when it's colder than this (winter) so I haven't really pursued the problem. When it's warmer than 45 it idles fine.

Second Noel's too rich mixture suggestion. Now you need someone w/ 3.6 insights to tell you why and what to do about it. At least this will keep your thread alive.

Do your car have an ISV (idle stabilize valve)?

still looking

I"m going through the same issue right now. after searching around, I have it narrow down to the idle control valve. I just order it from our host. it should be on my door in a few days. Once that one comes, I'll tinker with the old one(take it a part etc) as stated on the board before. Anyway, I'll keep you informed!!

keep us posted if it works, Kevin

I had a surging problem with my 3.2. I replaced the ISV, O-2 sensor, and head temp sensor. Nothing helped. I then had the good folks at TRE adjust the mixture. Problem solved!

I dont believe you can set the mixture on a 3.6, Kevin

Do you have a lightened flywheel?

Yes, I do have a lightened flywheel. I think I know what you may be thinking. When I first got the car back in December it would stumble a little bit when coming to a stop which is to be expected with the lightened flywheel. But that has stopped and except for the idle hunt when cold the engine has been starting and running like a raped ape.
Tom

Have you checked all the lines for a vac. leak? Perhaps at the fitting to the distrib?

Yes,
I did check all the vac lines. If it was a vac line wouldn't it affect it cold or warm?
Tom

Not always. Sometimes as things warm they fit tighter. I had the same problem with a Bimmer, and similar problems with the P car. Intake leak of some sort is a possibility. Some people spray brake clean or something around the intake to see if it sucks it in and temp. blocks the leak. Hope I'm not sending you in the wrong direction.

Actually I have a clue, Make sure your throttle is completely returning to stop, it must make contact, My car just smells really rich when i start it and has an irratic idle, so i may replace the throttle position switch, but make sure your throttle cable is not to tight, Kvein

Kevin,
As a matter of fact I did tighten the throttle cable just before this started happening because I thouht it looked a liitle loose. Maybe I did tighten it too much. I'll check. Thanks
Tom