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I'm having trouble with my '80 GTSi, I recently changed the timing belts, water pump and other belts, I used cam locks to change the t-belts, and after reassembly she wouldn't run very well. So I pulled the cam covers to check the cams, thinking one must have slipped, and after inspection they were all lined up correctly, so reassembled with new gaskets, etc, and still won't run very well (no surprise there but now where's the problem?). Seems to me to be "missing" it rev's OK but won't idle, and backfires, fuel delivery seems off as well. So I'm a little lost as to where to go next, is the Magneti Marelli DigiPlex the culprit? or the Bosch Jet-tronic, who knows...??? I'm struggling to find where to go next. Any advice is appreciated, Thanks - Nick
 

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Have you checked the ignition timing? I don't know much about the Digiplex ignition but I'm assuming it runs off the back of one of the camshafts and when you replace a worn out timing belt with a new tight one it will affect the ignition timing.

Revs OK but won't idle and backfires, sounds like the ignition timing is retarded to me. Put a timing light on it and you'll probably find that you need to advance the timing a bit. My 2 cents.
 

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Thanks Pete, I've kinda been thinking the same thing but I've no idea how to adjust the timing on this system. No "distributor" to adjust, best as I can tell the vacuum advance is controlled by the DigiPlex unit, and I can't find any info on these units so hoping someone might know where to look or what to adjust? Thanks again and any info, suggestions, or shove in the right direction is very appreciated! - Nick
 

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Finally.... Success!!! I've found the problem and now she's running like a champ!!! Turns out that a vacuum line had come off of the the aux air valve, thus like having a 1/2 hole in the hole vacuum system! Affects the DigiPlex ignition advance, the fuel pressure regulator, etc, etc, etc... I thought I had looked the system over pretty well after I completed the belt and water pump work but apparently missed a line, and caused myself a lot of grief! I guess one bit of advice to anyone with an injected car who does their own maintenance - "WATCH THOSE VACUUM LINES!!" Gotta say I learned a bunch and feel pretty good about tackling the timing belt project, but lessoned learned to be extra diligent about what you might bump or accidentally move. Thanks - Nick
 

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Good work, Nick, and thanks for the follow up with resolution. I will actually be replacing all of my vacuum lines and hoses soon, and I will be mindful of your saga!

Enjoy your Ferrari! :)
 

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Discussion Starter #6
Few pics of recent work...

Thought I'd post a few pics of the timing belt change, water pump change, and cams. I originally used a set of cam locking devices to lock the cams together, and they worked very well. I did remove th valve covers in the end but only due my doubts about my work after the belt change, all said and done didn't need to but was an "experience", so a few pics! I did all of the work in my garage and with just basic tools other than the cam locks. Just took my time and all said and done it all worked out well.
 

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Congrats Nick!! Thanks for the follow up and the pictures.
 
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