Date: Fri, 11 Mar 2005 01:56:44 +0000 (UTC)
From: Craig's C900 Site <>
Subject: Re: Troubleshooting the Bosch CIS cold start system

Paul Halliday <> writes: >> 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. >I'll look into the WUR ... Tom has provided me with some troubleshooting >ideas. I read Tom's comments too since the CIS injection system in my C900's (1983 900S and 1985 900i - both NA) is still a bit of 'black art' to me. 8-) I've been told to try changing the warm-up regulator to see if that fixes the cold-idle problem with my 900i (the car that I fixed the brake master cylinder on yesterday), and i do have a brand-new one here but it's a different part number (doesn't end in 136) so I'm not sure if it has the same pressure settings. Apparently there are many variations of the warm-up regulators that are set up with different pressure settings to suit the engine they're intended to be used with. The warm-up regulator still fitted to the dead engine in my 1983 900 gli is a different part number again. So I have two I can try. doesn't look hard to change - just relieve the fuel pressure, disconnect the two fuel lines, the electrical harness, and unbolt the old one. Reverse that to install the new one. Anything else that needs to be checked to change a warm-up regulator? Perhaps Tom might comment about this? I don't have anything in the tech library section on my C900 Workshop site at "" about warm-up regulators but there are some good references in other sites (might have one of those already linked). >>> 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? >I did measure this myself. I have a Gunson gastester, which read 3.7% >pre-MOT and the MOT station declared it 3.9%. I have re-checked since, but >it was a little windy ... Hence my guess at between 3.5% and 4%. Ah ok I actually used one of Gunson's Eezibleed kits to bleed the brakes on the 900i yesterday. The old brake fluid which the new fluid pushed out was horrid! Almost black like old engine oil in the line to the right-rear caliper. Oh one other thing - anyone who does buy an Eezibleed kit to do brake-bleeding themselves should use the thin 44 mm washer in the plastic cap supplied with the kit that fits on the brake fluid reservoir mounted over the master cylinder. I used the thick washer but it didn't make a 100 percent seal so when I had the air supply hooekd up to the 'Gunson chamber' (the chamber holding the brake fluid supply that's pushed by air pressure through a tube into the fluid reservoir on the master cylinder as the lines are bled out), brake fluid was very slowly leaking out the top of the cap screwed onto the master cylinder reservoir so I was flushing it away with clean water out of the plastic watering can every 5 minutes or so. 8-) 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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