weird one.. From cold the engine idles correctly then over the course of a few minutes it gets faster (approx from 800 to 1000rm). What could be going on?

Also there is pretty much no difference in acceleration between 1/2 throttle and full. I may be able to solve this as I think the Stage 2 throttle is just stuck.. sound about right?

When the engine is hot, try opening up the airbox and see if the choke flap is fully opened. If it's still partially closed, that might be why its idling higher and not pulling as well.

weird one.. From cold the engine idles correctly then over the course of a few minutes it gets faster (approx from 800 to 1000rm). What could be going on?

Also there is pretty much no difference in acceleration between 1/2 throttle and full. I may be able to solve this as I think the Stage 2 throttle is just stuck.. sound about right?

I should have added, this is it idling just after the choke has released.

When the engine is hot, try opening up the airbox and see if the choke flap is fully opened. If it's still partially closed, that might be why its idling higher and not pulling as well.

Hm, shall try this.. Bt why would it close after having opened? seems odd as it happens when the car is completely still, so there is no way the choke housing can get any cooler.. I've checked the coolant hoses and they supply fine..

You may have an air leak, this would be most likely to be on the carburettor base mounting.

Try spraying some carb-cleaner around there when the engine is running and see if there is any noticeable change in engine speed (which could indicate an air leak.

Or you could use a length of plastic hose, one end placed in your ear whilst you move the other end around the end around the carburettor/inlet manifold area. You would then hear any air leak (as well as clear the wax from your ear!)

Regards.

When the engine is hot, try opening up the airbox and see if the choke flap is fully opened. If it's still partially closed, that might be why its idling higher and not pulling as well.

Hm, shall try this.. Bt why would it close after having opened? seems odd as it happens when the car is completely still, so there is no way the choke housing can get any cooler.. I've checked the coolant hoses and they supply fine..

What he means is that the choke flap never fully opened in the first place.

It should be closed at cold then opening as the car heats up, before activating the auto-choke at cold, check how open it is and see if it opens any more by hand gently, then activating the auto choke should close the flap, warm the engine till the fan kicks in and see if the flap is fully open.

You may have an air leak, this would be most likely to be on the carburettor base mounting.

Try spraying some carb-cleaner around there when the engine is running and see if there is any noticeable change in engine speed (which could indicate an air leak.

Or you could use a length of plastic hose, one end placed in your ear whilst you move the other end around the end around the carburettor/inlet manifold area. You would then hear any air leak (as well as clear the wax from your ear!)

Regards.

Have tried the wd40 spraying thing around the carb.. but haven't been that thorough or specific about the base flange.. Thanks.

Out of interest, why would that mean the engine revs raise? This is after the choke has fully let go..

Internal combustion engine is just a big air pump.

The throttle plate reduces how much air can be sucked in.

When the manifold warms up it expands so a tiny hole gets large enough for more air to rush in.

Like opening thebthrottle more, so engine spins faster. But the leak is unmetered by the carb so does not suck more fuel from the jets and mixture is leaned. Lean gives more heat and power, engine spins faster. Does not matter at idle, but can melt spark plugs and pistons under prolonged load.

Heated manifold means fuel droplets stay in suspension (emulsified with air) rather than condensing on floor of inlet manifold. More fuel to burn, revs rise.

Pierburgs are designed for a fast idle of 2000+rpm (the GK model for 3300rpm says ruddies) for rapid warmup to best operational temp.

Haven't you been playing with the fast idle?

Secondary stage throttle stuck?

Might be the stage 2 pulldown diaphragm or its linkage.

That's unlikely, I'd check for jet blockage or air leak.

But does thesecond throttle butterfly plate move freely by hand (engine off, pull cable, shine torch down).

But I recall it needs vacuum to engage so you'll need a hand suction pump to simulate engine under load.

I suspect really the only way to detect wether the stage 2 throttle is working is by turning the throttle quadrant past the stage at which the vacuum unit is supposed to push down.. I know the diaphragm is functioning correctly as I gave it mouth-mouth when the carb was off lol.

It would appear the stage 2 throttle isnt moving properly. I got my sister to put her foot right down and looking at the stg 2 quadrant it was only moving like 5mm (wheras I can move it much further by hand..

I tried sucking the pull-down hose with it attatched to the hole that goes into the carb, seems like it isnt that free. So I connected a bike pump and put a few bar though it. This has helped a bit. There is a definate increase as you go past half-way, but not quite proportional like you would expect.

Also, seems I do have a leak. I recently put the carb back together so I re-tightened the main bolts and screws and this has improved things. Will need to re-set the mixture at some stage over the weekend.

"but not quite proportional like you would expect"

Does your 2e3 have a throttle damper?

http://web.vip.hr/mbucek.vip/Pierburg_2E3.pdf

picture 4.54