Date: Sat, 05 Mar 2005 19:04:38 GMT
From: Paul Halliday <>
Subject: Troubleshooting the Bosch CIS cold start system

Hi everyone ... My car is a 1989 900 T8 Special. I have the Bosch CIS fuel injection system and the cold start/warm idle is really bugging me! If I setup the cold start right, it's great ... Then when it's warm, it's too warm. If I set the idle right when warm, I have to hold my foot on the accelerator a little more than I want while the car warms up. Okay, I understand that until the car warms up, the auxiliary air valve will be open and the cold start injector will be pulsing fuel into the intake manifold. My auxiliary air valve has no current when cold and about +12V when warm ... That's good. What is supposed to happen to the cold start injector? Should it have current when cold and none when warm? Also, I have setup the throttle stop screw to "just touch" the throttle plate and then a further one third of a turn. This is perfect for cold starting. When the car warms up, the vac is sometimes right and sometimes a little too much at idle. The car runs a little warm too. I'm thinking it could be a vac leak but can't trace it by clamping hoses when warm. My air/fuel ratio is set to between 3.5% and 4% carbon at warm idle. Any ideas? My mixture metering plate seems to be able to be pulled up a little too easily ... Could this be an issue? I read in the Bosch CIS manual that there should be even pressure when lifting the plate up ... Whatever than means :) Your thoughts, as usual, will be very much appreciated. TIA, Paul 1989 900 Turbo S

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