Club 80-90 Forums

Hi, Confused as my coil is positive on both the posts. Van runs but over 50mph loss of power.

My splittie is +ve and -ve and think the t25 2L Aircooled should be the same.

Please can anyone explain what is wrong.

I have a green lead that goes to what should be -ve side of coil? what is this?

I have used a multimeter and both sides give 12 volts. On my split only one side is 12volts readout

thanks

Do you have the standard electronic ignition system? Did you test the voltage at the coil while the ignition system is fully connected? If yes, then when the ignition is on but the engine isn't running the coil negative terminal whilst connected to the amplifier will be isolated, thus the voltage on the positive side will feed through the coil LT winding to give a reading at the negative terminal. To ascertain if something is amiss, disconnect the wiring from the coil and check for voltage at each wire. When the ignition is switched on there will be battery voltage, (minus a bit - the wiring will be quite old now ), on one, and nothing on the other, only when the engine is running will there be a switched negative on the other, but it pulses at engine speed so without a specific bit of kit rather difficult to measure.

If it runs at all the ignition isn't faulty - although conceivably the timing could be set wrong, but that's a setup issue rather than an ignition fault per se.

Hi, thanks for the reply. With all the wires in place when I turn on the ignition I get +ve reading on both sides of coil. I also removed the coil and just connected the +ve feed to the coil and the other post also read +ve.

Also as there is no condensor, being electronic ignition, what is the green wire that goes on the -ve post?

cheeers

vw92h wrote:Hi, thanks for the reply. With all the wires in place when I turn on the ignition I get +ve reading on both sides of coil. I also removed the coil and just connected the +ve feed to the coil and the other post also read +ve.

It would do that - why that's so is hopefully explained in my post above.

vw92h wrote:Also as there is no condensor, being electronic ignition, what is the green wire that goes on the -ve post?

One side of the coil LT is permanently live the other is a switched negative that's on to charge the coil and off to cause the spark, just the same as in points ignition, the green wire is the coil LT negative and is connected to the ignition amplifier, it is a switched negative that's turned on and off electronically according to the pulses from the pick-up, (Hall sensor), in the distributor.

When the ignition is switched on and the engine is not running the coil negative is isolated by the ignition amplifier, this is deliberate and is done so the coil cannot overheat by being charged but not discharged. In this circumstance the coil will be live at the positive terminal, and the negative terminal will be isolated from the chassis/engine negative, (earth), so the negative terminal of the coil is connected through the coil winding to the positive = positive at both terminals. This is not a fault.

Hello,

A good and concise explanation of the Hall system coil....

IMHO, If you have any real problems with this 30+ year old system, go backwards in technology and fit a Bosch type SVDA distributor, costs less than a new Hall unit.

On an Aircooled, especially a twin carb setup, a points distributor running at 8 degrees btdc can give a significant improvement in performance at very little cost, ( the dizzy in the video being bought on e bay for about a tenner.)

http://www.youtube.com/watch?v=4qayyc9Z4E0" onclick="window.open(this.href);return false;

Part 2 on the same page.

Hope this is of interest.

Cordialement,