I'm currently looking into some electrical problems on my Focus. I've a couple of other threads going, looking into various error codes relating to the PCM/IC modules.

While reading another thread (here), someone mentioned a problem whereby the engine shakes when stopping the engine:

"the ECU switches off the injectors and operates a vacuum unit fitted to the inlet manifold to prevent engine 'shake' as the crankshaft and pistons come to a stop".

This was apparently taken from a Haynes manual for a Mark 1 car. Mine's a Mark 2, but I'm suspecting the same mechanisms are fitted.

My car is also shaking when I kill the engine. There's also an accompanying whine.

There don't seem to be any error codes relating to this, but perhaps it's caused by the same problems I'm looking into. Does anyone have any more details on what this problem might be? e.g. Which modules it's related to, and what I can do to investigate further. I haven't found any other threads relating to this, though could have been looking in the wrong way.

Thanks in advance :)

ive had this since i bought the car, i thought it was normal due to it being an old type engine, or that my mounts are worn. i would keep an eye on this if you find something that is causing it and the fix

Before my car was off the road - which is a couple of years ago now - it definitely didn't do it (the car was/is low-mileage, and I would have noticed - I'm paranoid about stuff like this). Now it's up and running again, it's a very noticeable, and happens every time I power down the engine. I didn't look into it before now because I had bigger problems to deal with (i.e. all the engine management issues), though I'm now suspecting they're all linked.

Hopefully someone can tell us what the problem is (or that I'm actually talking rubbish, and Mark 2s don't have the feature mentioned about Mark 1s... ) :)

Update (and closure) on this old thread....

While reading up on another problem, I've come across the "anti-shudder valve", which can get clogged up, causing it to get stuck open. Its job is to close when the engine is turned off, which stops air getting to the engine as it winds down. If it gets stuck open then the engine shudders on shut-down. Solution is to clean it. (Which I haven't done yet, but will do.)

Searching "anti-shudder valve" on the forum will bring up other threads.