928@AMG

Hi ,

does anyone here have experiences with a Permatune or MDS CD ignition box in the 928 ? Reliable or not ?
I have a '80 928S Euro with ignition hassles . I've changed all cables, spark plugs , distributor cap , ignition coil etc , still weak ignition .

Thommy

Jim bailey - 928 International

Have you changed the green wire on the distributor?, the two series Ballast resistors .4 ohm and .6 ohm ? If you temporarily put full 12V to the small plus terminal on the coil does it run better ? have you checked the new wires for resistance? When all is working correctly you should have a very good spark.

jeff jackson

Hi Thommy...congrats on your very first post on the Rennlist 928 B-Board. I have no personal experience with the MSD ignition amplifier/ multiple spark discharge box, and haven't yet "heard" of the Permatune unit, but can say that "typically" the 928 factory ignition system works pretty well. And, barring other tuning and engine issues, should only require infrequent spark pkug replacement, and should give you reliable starting and proper ignition response throughout the engines operating RPM range. Has there been any modification or alteration of the stock ignition wiring to this point? If not, do you have the manuals ? I'd first try to correct the factory ignition, vs. an upgrade that might try to mask an existing problem...

FlyingDog

What plugs and what wires did you use?

928@AMG

Hi Jim,

many thx for your advice . The green distributor cable should be ok , I can't see any damage. I'll do some more testing this WE , check the resistors , wires and keep you informed . BTW the spark plug wires are new ones, original Beru .

928@AMG

@ FlyingDog :

I have original Beru wires & Bosch WR7DC plugs .

@ jeff :

You're right , it seems better to check failure first . The ignition system iand engine is all stock (300 hp CIS fuel distribution ) without any modifications yet .

FlyingDog

You have the right wires and plugs. Did you gap them correctly? (I forgot to do that to the first 4 I installed )

PorKen

I had problems revving over 4500rpm on the dyno, and traced it back to a Permatune box I had bought used off eBay.

I've had no problems with the stock Bosch. If the green wire is not green, replace. The pickup in the distributor is replaceable (a 911 part), check for crumbling plastic.

928@AMG

Thx @ all for advice !
I think its the best to keep the original Bosch ignition box .

For my ongoing ignition hassles I've created a new thread .

Thommy

SMTCapeCod

I am running the perma-tune. I bought it when I suspected the stock TSZ box of causing some issues. Unless its responsible for my current quirks, its done OK. I didn't expect any real gains when I bought it, and I don't think there were any. Last time I checked their website it said they were going through design revisions. That was some months ago. I used to have a good rapport with an owner in Canada running an MSD unit in place of the TSZ box, said it worked great. At least with that you get mutiple sparks. I decided that I wasn't up to figuring out the wiring scheme required to run it properly.