View Single Post
mooney265 mooney265 is offline
Tinkering Pays!!
mooney265's Avatar
Join Date: Sep 2008
Location: New Orleans
Posts: 1,365
Originally Posted by T77911S View Post

the meat of it is, its the coil wires from the CD unit.

i have also discovered something about the 930 that i dont think a hand full of people may know. but then on this site, you never know

here is the fluff:
first the + wire has a cut length ways in the wire but it is near the end, and under it and i could not see it at first. it looks like it was done with a razor blade. it was not near anything and thought maybe it was just cut.
so i ohmed them out and was getting unstable readings. BTW, remove the wires from the coil and CD to do this. after a whil e of messing with this i was thinking how could i check this out to be sure. so i made 4 short jumper wires to go from the connector for the CD to the CD unit. then i made 2 long ones to bypass the coil wires. i should have taken a pic, but i was not proud of how it looked. i had to put some thick paper between the connectors on the CD unit. they were very close and i did not want anything shorting out. then i wrapped it with tape.
i left the CD unit sitting on the shelf and thought, let me just ground it just in case. so i used one of my jumper wires with alligator clips to ground it.
so i fire it up and can tell it sounds a lilttle better. so i drive it and it seems all better, but i need to get it hot to be sure. so i drive it around, against my better judgement and i would say it is about 95%, maybe 98% better. mixture still needs to be checked. so i turn around to go home. slowly, and it cuts off. i knew it was one of my wires. i short, it was the ground. BUT!
as i am connecting the ground there are some small sparks, THEN... THE FREAKING ENGINE STARTS UP!!!! no starter, it just starts running. scared the piss out of me! and actaully freaked me out. (for seveeral years now my head feels like i am in "fog" or hung over. sometimes i have to stop and really think about what i see or what i am doing and think is this really what i am seeing).
so i get in and start driving again. well, it does it again. i left the key on, wiggle the ground wire, FROOM! its runnig again. since i am not out on a busy street, i try it again. remove the wire, engine dies, connect it, its running. first i had to think, did i hear the starter, but no!
i guess this is why porsche kills the fuel pumps then the CD unit.

got home and connected it back to original. back to the miss. did not even have to drive it.

so the million dollar question. how to fix it.
i dont want to slice up the cover on the wire harness and i hate to see 2 wires running to the CD unit, plus i am going to have to cut wires at the plug for the CD. i am not thilled about my options.

now i wonder if the original coil is bad, the MSD coil that much better that it could cover up the fault with the bad wires?? i tried moving the wires around with it running and it did not change, so if anyone is thinking i moved the wires when i connected the MSD, i dont think that was the case. but i will put the original coil back in to check it.
So, what you're suggesting is the remaining compression, fuel and sudden spark are "restarting" your engine? Then, it keeps running [with fuel pumps] for an indefinite period? Pretty wild!!
LIVN80S - - Red '79 Porsche 930 Steel Slant Nose Conversion [in 1987] w. 46k miles 3.3L; 964 Cams; K27HF @ 1.0 BAR, with Garrettson Intercooler; Rarly Zork; CIS Flowtech Fuel Head & BL-WUR.
Old 04-19-2013, 04:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)