When slowing + putting the clutch in revs bounce to 2,000 then cuts out/500rpm

[ElliottSH]

Hi guys, been reading through, good forum got here!

Just bought a mk2 gti 8v '89 last month runs really well, nice condition no mods.

But when I put the clutch in (particularly in 1st-3rd) and slowing down the revs just 'bounce' up and then bounce back down. Sometimes the engine cuts out, there's no noise, I don't notice it's happened until the PAS goes most of the time...

I have three ideas of what it could be
1. Gearbox speed sensor
2. Idle valve
3. Dirty throttle

Any ideas? Is it possible there is a problem with the clutch it's self?

Cheers

Elliott

[Sgt_Lemon]

Does it do this at any other time? No other hunting
Maybe vac leak somewhere?

[russ-vdub]

I recon vac leak somewhere too. Or an inbalance in Idle & CO2 values.

[Sgt_Lemon]

As it only happens under certain load conditions you might struggle to find a vac leak on idle. I would just have a real forceful look round all the hoses when it's off. Remove the jubilee clips and wiggle it around looking for any cracks or splits.

[Mr Blue]

The best way to find an air leak is to spray carb cleaner on the pipes. Any increase in revs will mean that there is a leak.

Check the rubber seal on the oil breather (black saucer thing on top of cam cover). Seals the breather to the cam cover. Common for splitting.

Wont be any speed sensor related issue.