Chet 930

Permatune? Should have went to MSD.

02fly

I can't wait to hear the out come of this is sound like we have the same problem but I don't have a shop close so I'm the tech working on this and trying to get it solved in time to be at the Portland Parade. I've bypassed the over boost switch and the problem was still there could it be that the car is just way to rich? I have a 76 3.0 with stock 3.3 intake and intercooler K27 from power house and b&b header and muffler. What happens with me under full throttle the car starts to boost then just falls on it's face and starts bucking if I just give it half throttle the car runs fine and smoth all the way to red line. Sorry to high jack your thread and if you want me to start a new one I will but I think we may have the same problem. Thanks All

125shifter

I've heard of problems with Permatune but my car had one that seemed to be working fine before I pulled everything out. I'd also recommend the MSD route if it's not too late.

JBL930

When my ignition box (CDI) went the car died completely, it didn't run odd it just died!! I doubt that this would be the cause because after talking to the garage that replaced it he said they either work or they don't! Just my experience that’s all, hopefully it'll be a cheaper problem, they fitted a stock one on mine and it was a shock how much it cost, if I’d have been fore warned I would have gone the MSD or permatune route as they are so much cheaper. Good luck

srf506

I concur with Jonathan as I stated earlier, anything's possible but man that box usually is a hard failure, not an intermittent.

Chet 930

I've seen 2 CDI's in a 6 year span that were defective still work on an intermittent basis. One finally died after a few hundred miles and the other would work fine until it was warm and then it would cause misfiring. The one that went out completely was in my 89 930 and the other was in a 78 930.

JBL930

Mines an 87 and it's a five or six pin connection, can't remember? I think the earlier ones are three pin? I'm not sure but maybe that has something to do with it?? Who knows? Interested to see if changing zoomies cures his problem, keep us posted!! I luckily bought a spare brand new stock one (Bosch) off eBay a couple of years ago after I’d had mine replaced to take with me on long trips, thought it was a good idea!

Edited: I've just had a look and it's six pin, and it's actually called an "Ignition Control Unit" Number 930.602.702.00. Maybe i'm on about something different??

srf506

That's the box I'm talking about Jonathan.

Chet 930

The early ones are 8 pin until 77 then 6 pin from 78 until 89 ( or vise versa) and I dont know on the later turbos (91 on).

nathanUK '81 930 G50

I'm pretty sure my euro '81 has 6 pins.

PorscheMD

I've seen about two cd boxes over the last ten years or so as well that would miss under load. Usually they just quit all together. not that that hasn't been established yet. I thought they were all 3 pin until 77 then 6 pin? don't recall seeing an eight pin before. I have seen more trouble with the permatunes then they factory cd boxes. But, Permatune was bought out a few years ago and I believe they are constructed a little differently.

Y65MPH

Zoomie:

I had the exact same problem with my 965 running a 1 bar spring with a Fabspeed test pipe. At about 3500-4000 RPM the vehicle would cut out and then power back up abruptly. It is the overboost switch cutting the fuel supply, as many have stated. If someone was following you when this happened, I would bet a large cloud of black smoke would come out of your exhaust pipe. If it is your ignition I will be surprised.

Craig

zoomie

Got the car back Friday, i've driven it about 100 miles, no problems so far. It has a new (black) permatune box and coil, a new fuel boost switch. The gas smell is gone and it pulls harder on boost. Runs good so far. My mechanic prefers permatune becuase there is no rewiring, it's a plug in. MSD requires splicing into the car's harness. Next is up will be new plugs, wires, dist cap and rotor.

InC

Lets hope you have nailed the problem. Thanks for sharing. CDI boxes are always a hole in the pocket to replace! Has anybody tried the M&W CDI units? Heard it can only work well with interference free cables. Using it with original cables causes misfiring. Can anybody explain? thanks.

JBL930

If they changed the boost switch AND the CDI box how do you know the CDI box was bad in the first place?