Date: Sun, 6 Mar 2005 21:45:16 +0000 (UTC)
From: Craig's C900 Site <>
Subject: Re: Troubleshooting the Bosch CIS cold start system

Paul Halliday <> writes: >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! My C900's have 8V NA engines, so I tinker a little with the CIS parts on my non-registered but running car (the fawn-coloured 1985 900i at "") to work out how it all interacts. 8-) >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? I think that's how it works. The cold-start injector is, I think, connected to the circuit with through the thermo-time switch and the warm-up regulator so as the thermo-time switch warms up, the warm-up regulator reduces the 'richness' of the fuel mix back to a certain level and the cold-start injector is disconnected from power after a pre-set time, or sooner if the engine is warm already. That might be wrong, so anyone who knows better feel free to jump in here! 8-) >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. Did you measure this yourself? If you did, what sort of equipment did you use to work this out? >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 :) This area of the CIS system is the part I still don't fully understand. Regards, Craig. -- Craig's Saab C900 Page --> http://nospam/~c900 Sydney, NSW Australia Craig's Saab C900 Workshop -- For all Saab C900 Enthusiasts world-wide! http://www.nospam Come and explore our site, and check out our web-forums, mailing list, etc.

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