Mk3 Estate misfiring at speed

[mhall]

Hello everyone,

I've been reading the thread dealing with Mk3s cutting out and considered posting my problem there but decided it is a slightly different problem so thought I'd start a new topic.

Our family car is a '97 1.8CL Estate with an ADZ engine, manual gearbox and about 113000 miles. In the past six months it has started to develop a few problems after being extremely reliable for the six years we've had it.

The latest problem is a pronounced misfire at speed on motorways when lifting off slightly at about 70-80 mph. It doesn't seem to do it under acceleration at all and only when I've reached the speed I want and back off slightly when it misfires so badly that the car shakes.

From reading other discussions, it seems that the ECU relay may be a likely candidate so I had decided to replace that. I thought I would pull it out to check its condition. However, I can't find it! According to my Haynes manual, it should be in the top of the two rows above the row of fuses, third from the left. However, that position is empty and none of the other relays have number '30' marked on them.

Is the ECU relay in a different place on this model? Does the fault I describe sound like it could be caused by this relay? Any other ideas?

The most recent other problem I've had with it was cutting out as described by others elsewhere. The garage where we get our cars serviced and MoT'd around the corner had it for a couple of days but couldn't get it to do what we described but dismantled the fuel pump relay and that seemed to cure the cutting out but now it has developed this misfire but only at speed not if I'm running at say 40-50 mph.

Sorry if I haven't described the symptoms accurately enough but I'd be very grateful for any help.

All the best

Mark

[mhall]

Further information. Having pulled out and refitted all of the relays (I couldn't find a number 30) I seem to have made the car stall at junctions which sounds like the ECU relay problem, except I can't find that! It has only actually stalled once today, though. When it doesn't stall, at idle, the revs drop from about 950rpm down to something like 500rpm before picking up again.

We're really getting fed up now! Don't know who else to ask, are any VW dealers any good? Any decent independent VW specialists in Dorset or Hampshire?

It's a great car but this is getting us down. I just want to know how to fix it!

Any help would be very gratefully received.

Many thanks

Mark