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Old 9th December 2019, 14:22   #1
pletevl
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Default engine revving on it's own

Hi all,

Does anyone know why a K series engine would suddenly decide to rev up and down, from around 800 rpm and going up to around 1200 rpm, all on it's own when sat at a junction, up and down, up and down...... ?

The IACV valve was set on T4 in the summer.

Thanks.

Pete.
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Old 9th December 2019, 14:42   #2
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Every time that's happened to me it's either been the valve or an air leak somewhere that makes the valve keep operating in an attempt to stop the engine stalling.

Take off the valve. Give it a generous spray with carb cleaner.
If that doesn't work, then have a hunt for an air leak pulling air in through either a gasket or seal.
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Old 9th December 2019, 14:52   #3
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Engine off, ignition on, press accelerator pedal 5 times quickly, ignition off. restart car.
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Old 9th December 2019, 15:12   #4
pletevl
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I did this but why should I need to do it in the first place. Like I said, it was all setup and reset in the summer.
I will hint for an air leak.
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Old 10th December 2019, 19:43   #5
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I had this a few years ago on my turbo, Pete.

Turned out to be one of the little black hoses (from the turbo or air inlet side, I think) had come off the inlet manifold. Just popped it back on and it was ok again.

Although, I've no idea why it came off in the first place

So check for loose or holed air hoses first (easy fix).


Cheers,
Karl.
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