wierd behaviour with stalling engine on 89 900i

Hi I've posted stuff about this in forums at saablink.net and classicsaab.net, but I figured I'd raise the issue here as well without re-posting the stuff on the forum sites.

Basically, took the car for rego check yesterday. Drove fine there and back home. Went to go somewhere later after paying for rego and insurance, and the car stalled out the front of the house. Had to tow it around the back with one of the other cars (81 turbo, just out of rego last week - mwah!).

Did a lot of testing of components all over the place and ended up getting the engine to run again today, but I don't think I've actually found the problem as it still behaves erratically, and I'm thinking it's either a problem with the ECU itself, or perhaps the AMM or AIC. I tested the AIC using the Bentley manual procedures and it was fine, but the wiring might not be. The AMM (-013 type) has never given trouble before and the platinum wire is not broken.

At the moment I'm thinking the ECU itself is the problem - I thought it could be the fuel pump but I ruled that out early on during testing of things this morning. I know the 89 c900 ECU's are apparently known to have problems, but this is the first time the engine has behaved this way. It cranks fine, fires fine, then at some point later on the CEL comes on and the engine dies like the fuel pump has stopped (but it hasn't). This is why I intitially thought the AIC was buggy and perhaps it could still be. Don't have a spare at the moment though.

I'm going to attempt to drive the car to work in the morning and with luck it won't fail on me. 8-) Short of trying a replacement AMM and/or AIC, and perhaps also a replacement ECU (don't have spares of any of them currently), does any of the behaviour I've described here or in the forum posts indicate something specific to those of you with a lot more experience on the 16V c900's than me?

Regards,

Craig.

Reply to
Saab C900 Viggenist
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Check the Hall effect sensor and the ignition amplifier. A can of 'Frozen air' is useful to diagnose these things.

Reply to
Marty

I've suspected the hall sensor (mounted down near the crankshaft pulley) for some time, but it doesn't explain the strange behavior when I've run the symptoms past a bunch of people here.

I'm going to try to borrow a replacement ECU from a Saab parts place here in Sydney to try out, and get a spare AMM as well since that's a component known to give stalling and other hard-starting problems when faulty.

As for the ignition amp, in my car it's integral to the coil and I have not (yet) seen a new one of those special coil/amp units appear on Ebay as a new part. 8-)

Craig.

Reply to
Saab C900 Viggenist

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