CDS/Ignition woes

stuttgart900 · Post by **stuttgart900** » Thu Jan 24, 2008 1:10 pm

I seem to have an intermittent ignition fault... Car starts fine, runs well until it gets warmed up then goes dies under no load (traffic lights or roundabouts generally) then will not start. The car is a US spec '72 MFI car. Checked distributor, coil, leads, points etc. but no spark. Then out of no-where is will start and run again once it has cooled down it seems.

I have tried the plug lead out, plug in routine and no spark - although once I did get a single yellow-white spark but nothing again. Wiring seems OK I think and the distributor seems to be sending a signal to the CDS. The car has a 'Perma-tune' CDS in place of the Bosch unit (227 200 001??).

Any ideas or suggestions? Thanks.

impmad2000 · Post by **impmad2000** » Thu Jan 24, 2008 1:37 pm

Sounds typical of a CDI failure. The Thyristor stops working when hot. I have fixed the Bosch CDI's before, but never looked at a Permatune unit. I noticed there was a CDI on ebay at the minute. Becareful as the case has a picture of a 6-pin, and yet the CDI has a 3 pin connector!! I'd ask for some picture of inside the case if I were buying it. I'm happy to look at the supplied pictures for you, as they tend to look pretty rough in a good unit !!
Cheers
Tim

stuttgart900 · Post by **stuttgart900** » Thu Jan 24, 2008 1:44 pm

After writing this question - I just tried the car again and lo - it started first, second and third time with no problems! That was after a full morning of trying to get it going... Thanks for the advice on the ebay unit - I am sure my unit has a 3-pin connector... I will try and get some pictures...

jimbow · Post by **jimbow** » Thu Jan 24, 2008 5:49 pm

I would agree with Tim, My car had the same symptoms as this, very frustrating and embarrassing when you cruse to a standstill at the side of the road!

I put an MSD box in and it has been great since then.

stuttgart900 · Post by **stuttgart900** » Thu Jan 24, 2008 8:44 pm

Thanks for the advice. What model is the MSD unit and where did it come from?

jimbow · Post by **jimbow** » Thu Jan 24, 2008 10:21 pm

stuttgart900 wrote:Thanks for the advice. What model is the MSD unit and where did it come from?

Its an MSD 6AL, I got it from Ebay, a few vw and american speed shop sell them too.
The MSD is a bit bigger than the bosch unit and does need a bit of rewiring to fit. It also has a nice smooth cut rev limiter built in.

Read my CDI saga here: http://www.ddk-online.com/phpBB2/viewtopic.php?t=16230

stuttgart900 · Post by **stuttgart900** » Sat Feb 02, 2008 8:32 pm

Still trying to fix the ignition problem... It has now been faultless, but confidence is rather low. The car seems to have a poor earth to the CDI and the relay chassis it is attached to - and I think this may be the root cause.

Any more advice gratefully received.