DDK - Die Deutschen Klassiker

Took the Porsche into work today - well the sun was out this morning and I've bust my Bus' gear linkage through over zealous testing of a new shifter!

Fine driving into work. Wouldn't start easily tonight though, once it did it ran like an absolute pig, spluttering, missing etc.

Anyway, pulled in at a petrol station, checked over leads etc. etc. and seemed better for the last bit home although still missing at higher revs.

Bad Bumble Bee Pig!

My things to check, what would your list (in priority) be?

Bootsy wrote:My things to check, what would your list (in priority) be?

CDI box

Bad luck Mr. Boostsy - I know how you feel

P

it seemed to right itself after it warmed up and then only seemed to miss slightly at higher revs. Still stick by that diagnosis?

and then once back in the garage, started on the button?

Bootsy wrote:and then once back in the garage, started on the button?

Dunno - does sound odd - they do have their tempremental days

The RS started coughing and spluttering and it got progressively worse - ended up the day before CLM farting like a goodun - swapped out the CDI from another car and the problem sorted itself - thanks to the kind help of two DDK'ers I travelled south with two spares dread to think how you'd get an AA man to understand 70's Porsche ignitions

P

Best place for a CDI/Ignition Box if required? Anyone got one going cheap (I know, very funny!) Will mine be running a 3 pin? (it's a 72 2.4T engine remember)

I have been testing a few CDI boxes, and a temperature related fault is not uncommon. Usually gets worse as it warms up. Trouble is, the part that seems to cause this (Thyristor) is NLA and modern equivalents just don't do the same job. I'm looking into a fix for thisbut no news yet. Bootsy, I can lend you my working box if you'd like to try it out, just to rule out the CDI if nothing else... It'll be a little while before my charriot needs the CDI again
At Elvington a DDKer (no names !) had a bad missfire... I put the CDI plug back in properly and he was sorted. Well worth a quick check for connection problems.
Cheers
Tim

Thanks, I'll have a play around with mine over the next few days and then may take you up on the offer. I'm also looking into having mine recon'd - any suggestions where?

Well, I've fixed a few , but if the trouble is what I believe.... then I have a pile in that state ! I am currently investigating a solution. I am happy to take a look at the box anyway. You never know It might be an easy fix.
Cheers
Tim

impmad2000 wrote: Well worth a quick check for connection problems.

Yep especially earths

I feel your pain Bootsy, I've had just a few similar experiences

this is not a scientific measure but you can test the whole cdi system in one go if you fancy it, run an ignition lead straight from the coil with a spark plug connected and earth the body of the spark plug at the thread, I used a heavy guage wire with two big croc clips on either end of it, connect the other end to the fan housing and made sure the spark plug is a 1/4 of an inch away from a good earth point - the fan housing will do again, take off the points trigger wire from the dizzy, switch on ignition and repeatledly tap the trigger wire to another earth point (wear rubber gloves and use a pair of rubber handled pliers just incase), you should get a nice fat snappy blue spark coming from the plug, if you only get a small orange zzzt then you may have a weak box.

Also a good idea to have a look at your coil to make sure it's not leaking any goo, mine was and caused a bad miss and eventually killed off my cdi box.

Another thing if the car idles, start it and put it in the garage, dark with no lights on and look for a light show in your engine bay to be sure the ignition leads arent buggered.

Good luck old chap, I'm not very fond of electrikcery stuff and know how irritating it can be to try and diagnose these things.

It started ok this morning and idled fine - I'll take it for a run at the weekend and do some more investigating. Thanks for all the advice.

Not convinced it's the CDI now, although the weekend will tell me if it is or not.

Going to have a general check over, clean up connections etc. and fit new HT leads - where from?

I'd love to go http://www.magnecor.co.uk/ as I've heard gret athings about them especially the blue (mid) ones on a 911. Any experience? At £200 or so a set I'd like to be sure.

If not any recommendations?

Fitted Magnecors to mine just recently. No negatives. The are really well made, fit nicely. Would recommend getting the wire holders as they are quite a bit bigger in diameter than the original leads. Got mine from pelican. Being an Engineer and working for a materials company I was sold on the sales literature.

An engineer? Him?

Gary71 wrote:An engineer? Him?

I thought you were an optician