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Discussion Starter #1
I'm on my first Bosch car (89 Graduate). Two things:

1. Does L-Jetronic have knock sensing and spark retard capability?

2. The distributor passes the spark from the coil to the plugs at the proper time, and does nothing else, right? It's quite empty in there. The owner's manual says never to rotate the distributor. Does doing so change the timing? It must, right? Not that I plan to, but with the orientation of the spinning rotor and fixed cap, its relative must affect the timing. The ECU can alter the timing independent of the physical distributor?

Thanks for any elucidation.

Andrew
 

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1. Does L-Jetronic have knock sensing and spark retard capability?

No.

The ECU can alter the timing independent of the physical distributor?

Yes, (also in combination with the flywheel sensor and vac sensor), which is part of the reason you'll find the blade on the dizzy rotor seems so much wider than those found in mechanically advanced types.

Moving the dizzy body can really throw things out of whack as you may inadvertantly put it outside a range that the ECU can control through that wider blade.

Usually a miss would be the first indication you went too far as the ECU would be trying to fire at a point when the rotor wasn't in contact with a plug lead on the cap.

Static idle advance @950rpm +/-50 10deg +/-4 (F mark on crank pulley)
Advance @ 2000rpm 16 deg +/-4
Advance @ 2400rpm 30deg +/-4

Max advance is somewhere in the 37-39deg range (M mark on crank pulley if it's actually present)
 

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Discussion Starter #3
Perfect answer; thanks very much.

So I presume in normal operation there's no need to put a timing light on it? I haven't even actually seen any timing marks on the pulley yet, but it's a mess and maybe they're under the grease and rust?

Andrew
 

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Lots of L-jet info here: Spider L-jet diagnosis

I haven't even actually seen any timing marks on the pulley yet, but it's a mess and maybe they're under the grease and rust?
grease and rust?!? On an Alfa?!?! [manical laugh.wav]

Here's what you should be able to find under the 'grease & rust':
 

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Andrew,

When I got my spider the dist was loose. I put the crank at the TDC mark for #1 cyl and then aligned the mark on the rotor with the mark on the dist housing. Works fine so far.
 

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Discussion Starter #6
I found TDC with a dial indicator and marked it on the crank pulley; I'll have to see if there's a P anywhere near my mark. Thanks

Andrew
 
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