Scirocco Register

Seem to have an intermittent problem with my '89 scala injection. When revving the engine in neutral the revs drop off completely (sometimes to the point of stalling) at around 3,000 rpm or so, then bouncing back up, then falling away again etc etc. When this is happening the car is undrivable. When the revs drop off I can hear the solenoid clicking (think its number 62 - the fuel pump?) Just had the car running for 5 mins or so and now problem has gone away.

First port of call was to look for split hoses etc on the vaccum line but no obvious signs.

Any advice?

thanks!

Try a different fuel pump relay first.
If no better look at the lift pump in the tank, it may have stopped working causing the main pump (under the car) to work harder.

Could be the idle screw has come lose as the back of the throttle body, your car is fitted with an anti stall device which just keep the revs up. Get the car warmed up make sure all elecrical stuff is switch off then adjust the idle screw (its a bolt looking thing really, 7mm spanner needed) so the revs go up to 1500 rpm on idle then lower the revs to 950rpm ish (I run mine at 1000rpm in the winter) and see if thats any better.
As already said it could also be the lift pump failing, you will hear either the main pump getting noiser or the lift pump going quite but you should hear something differnet from normal if the pump is going, mine did it for a few weeks before I changed it. Lift pumps are about £25 but make sure you get a new filter on the bottom like this one, other places do sell them as well I think GSF Euro car parts may sell them as well, first one I found. You may also need to replace the bit of hose which links the pump to the fuel sender and make sure its the same lengh as the oringinal or the pick up will be to low or to high in the fuel tank there was some info on here about what sort of hose to use as it lives covered in petrol, rubber fuel hose does work but it seems to perish after a year or two.

http://www.ebay.co.uk/itm/VW-GOLF-MK1-C ... 2eba1fe9aa

I would try the free option first (idle speed) then go from there..
Keep us updated....

Thanks, I did play with the idle control valve a while back when the problem first occurred and it seemed to sort it for a while, will have another go tomorrow and see it makes a difference again. I put a new fuel lift pump on fairly recently so I'm assuming that can be eliminated. Still, will check tomorrow to see if I can hear it working ok.

Will update on progress tomorrow...

With the idle screw there is a rubber washer on it that may of perished, take the screw/bolt out (be carful not to drop it down the back of the engine!) and have a look at the washer if it looks OK try putting a little bit of thread lock on the thread to stop it coming lose. This is what happened to my car and thread lock has seemed to work.

Hmmm. Have had the idle control, washer is fine although put some ptfe tape on for good measure but revs still dropping away. Seems to rectify itself once warmed up. Will have a look for replacement relay as per above recommendation, maybe that will do the trick...

Problem finally sorted (after a trip to the garage). Seemingly a dodgy coil, replacement fitted and seems to be ok.