Engine revving on its own/ smoking

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mines a money pit
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Engine revving on its own/ smoking

Post by mines a money pit »

Right, need to get to the bottom of my vans running issues and haven't a clue really!

Its a 1.9dg with the pierburg 2e3 carb.

When I start it, it runs rough for a short while and smokes (blue smoke), then it gradually clears itself and starts to rev up as if I'm pressing the throttle. It will keep revving higher and higher until I'm sure it will end up running flat out. If I load the engine the revs drop to normal level, until I let it try and idle, then they will race up again. Most of the times I've started it, it has done this, but a few times it has behaved more normally, including, typically, when I picked it up, when it was running pretty well :roll: .

Am I right in thinking its some sort of carb issue? It doesn't seem to be vacuum lines as that was my first port of call after previous carb issues on my MK2 Golf were caused by split lines. They looked fine and the few suspect ones I've changed.

Any ideas and advice would be great as I need it running right to diagnose other potential problems!

In case that makes a difference it had been standing for 5 years or so before previous owner got it.

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CovKid
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Re: Engine revving on its own/ smoking

Post by CovKid »

Blue smoke - oil. Sounds like the engine is running on oil from the sump. If its not been overfilled, the oil is getting into combustion chambers via rings, valve guides or somewhere else.

Standing for five years won't have helped.
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kevtherev
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Re: Engine revving on its own/ smoking

Post by kevtherev »

To add to Cov kid..
The pierburg carb has a fast idle mechanism to help cold starts.
It will stomp up to 2000 rpm when first set.
After the throttle is blipped it should reduce to 1500, then 1200, then 900.
This mechanism can stick.
search my posts for "fast idle" and you'll see it revealed
AGG 2.0L 8V. (Golf GTi MkIII)

mines a money pit
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Re: Engine revving on its own/ smoking

Post by mines a money pit »

OK, Thanks guys.

Looks like I need a new engine/ rebuild then if it is getting oil in combustion chambers CovKid? Was hoping that wouldn't be the case. Was hoping the smoke was over fueling and caused by the carb. Only does it when idling (not as much when warm) not when driving? Was going to do a compression test anyway so that should confirm it.

Had a look at your info on the fast idle mechanism Kev. Do you have to strip the carb down to sort it as the pics look like the top is removed from carb? Could be an easy fix if it just needs oiling/ freeing up :) .

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kevtherev
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Re: Engine revving on its own/ smoking

Post by kevtherev »

mines a money pit wrote:OK, Thanks guys.

Do you have to strip the carb down to sort it as the pics look like the top is removed from carb? Could be an easy fix if it just needs oiling/ freeing up :) .
By all means do what you can with the duct removed, but if the springs have come off or busted then it'll have to come off.
You should just be able to see the mechanism working
AGG 2.0L 8V. (Golf GTi MkIII)

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Re: Engine revving on its own/ smoking

Post by CovKid »

If its definately blue or grey smoke, its oil. Over rich is generally black, white/grey, coolant burning. Check as Kev has indicated but with it revving its nuts off and the colour of the smoke blue, it doesn't sound like an easy fix. Definately do a compression test!
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