Strange cold start problem 308

I have a strange cold start problem with my 1985 308QV. Whenever I start the car when the engine is cold, I have the following problem. For the first 60 seconds the car runs great and the idle is at 1,000 rpm (according to the manual 1,000 rpm is normal). After about 60 seconds the idle goes down to 500 rpm and the engine sounds as if it is missing and about to stall (it never does). After about 10 minutes the idle magaically returns to 1,000 rpm and the engine sounds normal again. What is my problem? Please help.

>>What is my problem?<<

YIKES!!!!

That was not the type of response I was looking for. What causes you to say "YIKES"?

Ken

Ken,

the type of problem you describe is going to take hands on analysis imo.

To even begin to be able to guess with any degree of hope of getting close, one at a minimum needs to know which system is the culprit, ignition or fuel. And even then on the internet it's stil a wild crapshoot imo.

If I had to make a wild guess, I'd say look at the electrical portions of the ignition systems first.

Regards, JRV

Hi Ken,

After you start the car it idles at 1000 RPM? That is not normal. Mine goes through a warm-up period at about 2500 RPM for about 2-3 minutes. Then it drops to 1000 RPM and idles there. As I understand it this is the normal process to heat up the cat.

I think what JR is saying is that the "problem" can not be pin-pointed based on the limited information given. It doesn't sound normal, but no diagnosis can be made this early on. JR is not one to take wild shots in the dark when confronted with a car that is not running correctly. That would only waist your time and possibly money. There is a logical process that you must go through in order to solve your issue. You can't get to point E without going through points B,C, and D.

Lets start with what/where should you start looking?


JL

Well, JR is up late again. Beat me to the post.

Ok, the fact that the rpms aren't climbimg to 2500 indicates that you aux. air valve is stuck closed. My AAV was stuck before and wouldn't go into high idle 2500 or so. It starts and goes to 1000rpm. Now onto the bogging issue. Could be many things but I will try to help isolate some ideas. The AAV adds extra air during cold start since the CSI is spraying and the WUR is in its lowest pressure setting(richest). To make a long story short it could be too rich causing the car to bog since it isn't getting its extra air. Idea #2 WUR (warm up reg.) when the bimetallic strip isn't functioning properly/resistance is out on the WUR can cause bogging on cold start and when you give the car gas it is very reluctant to take it. It will bog more then the rpms will rise slightly. Pressure testing will show if it is in the WUR. It sounds like first check your spark on all wires with a timing light, then the AAV, remove it, clean it, bench test it, replace it if is not functioning correctly, then move onto fuel pressures. HTHs.

Thanks guys. I have already replaced the coils, so I now they are not part of the problem. One questions I have is should all 308QV idle at 2,500 upon start up, or just the earlier carb'd cars?

JRV: I was not trying to be a smart ass, but I took your response to indicate the repair would require $$$$$$$$$$$$$$.

Ken,

ALL 308's have the high idle.

Didn't mean to scare you...not big $$$$$, but almost impossible to pinpoint via internet. Believe me, I would love this forum to be a miracle worker....., but I'm the first to see it's limitations.

Sounds like everyone has you on the right track though.

Regards, JRV

OK. My Aux air valve seems to be working fine. What else could cause my idle to be only 500 rpm's for the first 10 minutes?

Also, how can I simulate a cold start once the engine is warm? I will need more than 5-10 minutes to find the problem at hand.

Thanks.
Ken