Porsche Enthusiasts Club Forum

Last year I had a starting issue, well I sorted the problem (I thought) after replacing both reference sensors, the FPR and part of the fuel return pipe, I got her running up to temp. bled the cooling, checked the fans were coming on etc. I thought while she's up on stands I'll tidy up the underside a tad. I found a very small area of rust in the front of the offside sill behind the wing liner under the ABS pump so welded a small patch. Now she won't start. Have I fried the DME is the question? battery was disconnected but I forgot to remove the relay or disconnect the DME. I have fuel but no spark.
Anyone have any ideas please.

When it spins over does the rev counter bounce off the stop?
Is the fuel pump priming?
Is there any spark?
Fuses all OK?
Is there 12V to the coil?

The rev counter does bounce, I am presuming the fuel pump is priming, no spark, fuses ok, DME relay is new, will check 12v to coil.
Thanks

12V to coil

Keep them coming please

Rev counter bouncing generally means that it is sensing the crank sensors & ECU is OK. One side of the coil should have 12V on it. The other side is switched to earth to fire the spark.

Right. Just to check.

You have compression, fuel but no spark. But you do have 12V to the coil.

In that case I'd do as follows:

-Check there is 12V at the coil when turning over. If not you have found your problem ; the DME relay can do this and I think a dodgy FPR also can; but disconnecting a plug from an injector can rule this out. If you had 12ishV however I'd move onto the next step
-Get a spare spark plug and put it into the king lead from the coil and put it on the engine. If it's not sparking and the plug is good change the lead. If it's still not sparking with 12V it's probably your coil that is goosed.
-Assuming the above was OK remove the dizzy cap. Check that the carbon brush is in the centre. If this is broken you'll need a new cap. After this check for a spark on all of the HT leads.

I've been thinking along the same lines as you. Did a coil test as in Clarks but not convinced by the results so will get a new coil tomorrow and see what happens. The HT leads, dizzy cap and rotor are all about 200miles old, the coil could have been there for years, (nothing in the history).

Still scratching my head. New coil fitted........nothing
Is the rev counter needle bounce a definite that sensors and DME are ok?
From whats been said the mig hasn't caused the problem just coincidence. Will keep looking, oh how I dislike the dark art of electrics

As said despite stuff being new I'd still check it out as stated.

Only this week I've been caught out by a visibly damaged new part for my car .

FWIW I had a VW Beetle years ago that wouldn't start with new parts everywhere. The cause? A duff new rotor arm. I've seen the same thing happen on a Dolly Sprint as well.

Update, Sent the DME and KLR to https://www.augmentautomotive.co.uk/ecu-repair-service/ for sevice, some dodgy solder joint were found in the DME, I also fitted a new fuel pump and HOORAY she starts and runs, it's only taken a year to sort out. The brakes need bleeding then MOT time.

Update...... M.O.T. Pass, no advisories Now a new problem She is laying down a smoke screen like a WW11 destroyer when on boost So any advise on removal, repair or replacement of the turbo, it does look to be 30 years old, would be gratefully received. Don't we just love our classics.

Hi John

Try Universal Turbo's, I have had my turbo rebuilt twice by them now, my son recommended them to me...they will arrange pickup of your turbo and deliver when ready, turnaround depends on work required but it's not long. http://www.universal-turbos.com/contact.asp

regards

Pete