Date: Fri, 23 Aug 2002 19:41:42 GMT
From: bob stevens <>
Subject: cold start problem.

Hi, I know this might be a common topic, but I'm really stumped by my 1986 900S. It has a cold start problem, - only the first start of the day, after that it's fine. The first attempt will bring the RPMS up to a high idle, which will then drop over a few seconds, then stall. The next attempts to start may then fluctuate between high idle and almost stalling a few times, before finally stalling. A few more start attempts, or if I press on the accelerator a bit until it's settled, and it's ok. The car will start no problem for the rest of the day. I have checked and replaced the vacuum lines and several of the manifold grommets, and a vacuum gauge reads between 15-17. I sprayed carb-cleaner into the throttle valve, to be sure there wasn't any gunk that could affect idle speed, but it looked clean. The throttle position sensor also works correctly. I also removed and cleaned the AIC valve, tested the resistance across the three terminals (LH 2.2) and it seems to match up to the Bentley specs. If I start the engine cold with the AIC valve detached from it's electrical connector the engine starts and levels off around 2500 RPMS! I have no idea what this means, if anything. Then I measured the resistance of the AirMass meter and adjusted it to 380 ohms according to value I found in the service manual. How far off from this value would still be reasonable for a 1986 engine? And if I need to adjust this setting, how do I find the "sweet spot"? I even replaced the coolant temperature sensor with a brand new one. Does anyone have suggestions? Maybe fuel pressure regulator or pump? The car doesn't seem to have lost any power, in fact it runs rather well. Can I rule out the Oxygen sensor, because the engine is cold? Thanks, Bob

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