Erratic running speed

[pipworks]

Hi, I've got a 1.8ltr 1990 8V Digifant, recently it's started to run erratically.

It starts first time every time from cold, then, sometimes, when it's warmed up, the revs vary. If I leave it on tick over to warm up, after about ten minutes, the revs increase to around 3000, stay there for about 30 seconds, then drop down to about 900, and then bounce between them two figures?

If I accelerate when the revs are climbing, it drops, (a bit like over riding the auto choke), and then reverts to it's erratic behaviour?

When I am driving at around 2500 revs, I can feel it doing the same thing, I can feel the engine pulling and dying even though I've not lchanged my throttle position?

Sometimes, when it's doing it's erratic thing, it splutters really badly then grey smoke comes out the back, (which I assume is unburnt fuel?), and then runs ok again for a short while.

Some days it doesn't do this at all?

I've been told to clean the idle stabilizer valve, which I took off the other day, but I've no idea how to clean it or what with?

Any advice would be a great help.

Thanks in advance

[gti69]

Try cleaning the idle screw with carb cleaner too, this happened on mine and cleaning the ISV and idle screw did the trick!

Hope this helps.

[pipworks]

Hi again, I tried all these, it ran nicely for about 10 miles, then reverted back to it's spluttery erratic ways!

I've been told it could be electrical on the throttle switches, I can see the micro switch on the top, the full throttle one, but can't find the closed throttle switch?

Has anyone ever had problems with these switches? And can anyone tell me where the second is/how to get to it please?

I'm wary to take it to a garage, they'll try a new injection system on it, find that's not the problem then try something else. Before I know, I'll have a bill for ?2000 trying to solve this!

Is there any good electrical diagnosis centres anywhere?