problem - idle stabilising unit

[samk]

Hi All,

Had a breakdown on my trip to cornwall last week. It was a real head scratcher at first running really well for 6 hours then stated to loose power. Got progressively worse until we stopped completely. then wouldn't rev and would only manage to trundle along at 3 MPH.

Checked loads of components with a friend down there who is luckily a dab hand with VWs! After half a days tinkering we discovered the idle stabilising unit was to blame. We then cut it open, soldered a bit and wedged some plastic to fix it.

My question is what does the bloody thing actually do?! didn't seem to make much of a change plugging the 2 ends together when it was out. Why fit a circyit board to a fairly basic air cooled engine?!?! I am confused!

The van is now up and running but power is down 20 - 30 %. slower on acceleration, worse on hills and sat at 60 ish with foot flat to the floor. Could this be something to do with the positioning of the dizzy? we did tinker with it. Or, is it dirt in the engine/ plugs waiting to clear out after running it rough?

Thanks,

Sam

[VWCamperfan]

Position of dizzy probably. The timing has to be set with the idle stabising unit connectors connected together, not in the unit itself.
The unit will slightly advance the timing to allow the engine to have more idle RPM when it's dropping too low and possibly stalling.
You should be able to run the engine quite happily without the unit and the two connectors pushed together, bypassing the unit. If the timing is set correctly with this configuration and you are still having running problems then something else is at fault, possibly HT coil related.

[samk]

thanks Mark.


So, is it fairly easy to find out how the dizzy should be positioned? a doable DIY job that doesnt need a timing gun or not?

Also, forgot to mention that its a 2lt air cooled for anyone wondering!

[VWCamperfan]

Should use a timing gun to set the timing correctly but for an initial set up, run engine until warm, loosen adjusting nut/bolt on distributor so it can be turned. Now, turn distributor one way ot the other until the idle RPM of the engine is at it's max. Now turn distributor clockwise (about one hour on a clock face) to retard the timing. The engine idle RPM will drop and you should have a reasonable timing set up but I would have it confirmed with a timing light when you can.
If you have altered the idle adjustment screw on the carb when trying to find the initial problem then this may need to be adjusted slightly to bring engine RPM to where it should be on tickover.

[samk]

Great advice. I will give that a try and hopefully the problem will be sorted.

We did set the idle a bit higher once the unit was out and my friend did move the dizzy about so hopefully this is the cause.