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Jeff, your problems are related...
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Posted by Justin VanAbrahams [Email] (#32) [Profile/Gallery] (more from Justin VanAbrahams) on Mon, 28 Jan 2002 16:32:41 Share Post by Email
In Reply to: Bosch LH ECU gurus : HELP !, Jeff S2, Mon, 28 Jan 2002 15:20:02
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I am a little confused about what's going on here.... So you have an '88 non-turbo body, into which you've installed an '85 turbo engine. If I'm not mistaken, your '88 was an 8v, meaning it had CIS. Your '85 would be a 16v, making it LH. So you've brought over the LH Jetronic, and ditched the CIS, right? That sounds vaguely familiar to me... BTDT...

The condition which tells the ECU to deliver fuel is a tach signal, so if you're not generating one, the LH ECU will never power the fuel pump relay. You need to solve the ignition system problem first. You should be using the turbo's distributor, but you should be able to use either's ignition control module. Pull the distributor out of the head (don't disconnect it), and connect a DMM to the back of the hall effect connector. Spin the distributor by hand and verify you have proper voltage there - it should alternate from something less than .5v to something greater than 3v as the sender passes the pickup. On my '80, following the same conversion, I was seeing 4-6VDC here. If you've got a friend, have him spin the distributor while you take a measurement at the ignition control module just to verify it isn't a wiring problem.

Assuming this is working, and you have proper voltage and ground to the ignition control module, you have all the parts necessary for a working ignition system. If not, you've got bad wiring or a bad ICM.

If it is good, you now need to verify you get a tach signal at the fuel injector computer. Bentley has the tests for this - ~3VAC at the ECU IIRC. If you aren't getting this, something between the ICM and the FI ECU is getting in the way - check for continuity (with everything disconnected!) first of all.

I hope something in here helps... let me know if you have any additional questions.

-Justin

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