Johnny G Pipe

Hi folks

My car stranded me for the first time in 14 years..just after I serviced her, inc plugs and valves.

The bottom line is that she was running well but then coughed and died, would not re-start, despite DME relay and jumper checks, check HT leads in place, new caps and rotors, remove check and clean plugs..but she DID start when I switched the coil leads between the 2 distributors (and would not start when I switched them back).

This is confusing for 2 reasons. It suggests a problem in spark getting to one of the caps of course, but why does transposing the leads fix it?

The 2nd confusion is that testing each coil bank with a spark plug to ground last night, gave me a good blue spark on BOTH coils. Huh?

My best guess is that I have a bad HT connection downstream, which one coil is strong enough to get past, while the other is not - but that the difference is not visible in the spark test. Anyone agree?

Next question is what to do about it, and as this is all OG 1989 equipment, I think I might just jump in and replace both coils, both ignition units and the HT leads.

I can get new Beru leads off ebay for £270, new Bosch coils for £50 ea., and generic igntion units for £25 ea. So, I have had worse hits.

Interested in any comments, and also
- Are the Bosch coils OK now, there is comment in old threads that they are not?
- Is a generic ignition unit going to be OK? There are several around, and they look shared between a few manufacturers.
- What is the best way of getting the rear coil cover off - it fouls the bodywork no matter which way I pull it, and I am fearful of damaging something if I start getting into hulk mode with it!

Thanks for any input..

J/.

Tmistry

Have you checked the secondary distributer belt? Worth a look, though it may not be root cause.

Johnny G Pipe

Yessir! Belt isn't the original, I did it a few years back..I checked it anyway and it looks good, and both arms turn when the engine is rotated.

Silvertarga

The Bosch coils available now are absolute rubbish , and I believe that the ebay leads do not have the removable end pieces so save your old leads
I recently changed coils to the 993 coil pack and its a great mod, there is a thread on it in this forum, you will need your old coil leads..

Rear coil cover? If you mean the plastic cap pop it open with a large screwdriver..If you mean the bracket for the coils there are TWO 6mm allen head screws that hold it on, one on the top and one through a hole in the bracket

Johnny G Pipe

Thanks, I will search for the 993 coils mod.

Re the leads, they look ready to go to me:

http://www.ebay.co.uk/itm/Porsche-91...item43c2843f13

At this price I think I have to, at 130k miles and 26 years on the originals I think I should be seeing this is a service item rather than an optional extra.

Re the coil cover, yes it is the plastic cover. I popped the front one open and off no problem, but the rear one just wedges up against the rear inner wing when I try and pull it off. I think I just need to man up and give it a good tug, just wondered if there was more to it.

Cheers

Johnny G Pipe

OK..Thanks for the 993 coil pack mod link..also, looks like it is safe enough to trust a used set of 993 coils (although £116 for new is tempting..).
http://www.ebay.co.uk/itm/PORSCHE-91...ht_2766wt_1171

Also from a search, much more likely that I have a bad coil(s) rather than bad ignition modules.

..to ebay!

Silvertarga

The 993 coils use a different connector and if those new Beru wires dont have removable ends you will need to source a set of 964 coil wires and the 928 numbered coil plugs in order to do that mod.

Johnny G Pipe

OK, thanks for that - hopefully my current coil wires are good and I would just modify them.
I believe I can just use used 993 coil wires as a plug and play instead though?

Silvertarga

993 coils are mounted on the engine carrier and the 993 HT leads are much shorter so they wont work for the 964.

If your coil leads are bad you may be able to use a plug wire as a substitute ..of course if your Beru set has the removable ends then all you need is the 993 coil connectors..

Goughary

This may not be your issue, but just to throw it out there...I once had on beru distributed caps, the posts that are glued in broke loose. This cussed all kinds of problems. I only use bosch caps now and haven't had that issue again. But pull your distributed caps and check the integrity...just to eliminate that as a possible issue.

Johnny G Pipe

Thanks..the caps are new, one of the old ones broke exactly as you describe when coming off. But the new caps haven't solved the problem!

I have sourced the 993 coils and new 928 p/n caps and will try this mod first. Will report back, thanks Silvertarga and all for the input.