406oc.co.uk

My 406 runs perfectly well when cold, but after about ten minutes the engine over-revs when de-clutching to change gear even though I take my foot off the accelerator. Also, the idle begins hunting between 1000 and 1500rpm at about 1 second rate. Then, mysteriously it will stop and behave OK for about 5minutes before it starts the same behaviour.
Runs like a dream at normal highway speeds and has oodles of power.
Have checked the accelerator control and the resistance doesn't change even with external heating. No loose wires that I can see.
Anyone seen this? and could it be the wastegate in the turbo sticking shut?
Oh yes, there isn't any apparent indication on the ECU light, but haven't interrogated for any fault codes. Fuel pump is dry.

Cheers....Zeebee

Not sure about diesel cars, but a stuck (open) wastegate on a petrol turbo would produce more boost than you can wave a pointy stick at.

Tiny Tim wrote:Not sure about diesel cars, but a stuck (open) wastegate on a petrol turbo would produce more boost than you can wave a pointy stick at.

Yes, that's kinda my point. The reason I think it could be happening is that the revs actually go up as soon as I declutch which points to the wastegate not opening to dump the (now not required) boost that was being used during acceleration. That's only a theory though, I was hoping that someone might have seen it before or have knowledge of diesel turbo characteristics.
The rough part is that to even look at the turbo on the 406, the engine's gotta come out along with a bunch of $$$$$

sounds like the pump unfortunatley

jameslxdt wrote:sounds like the pump unfortunatley

Thanks, I thought so too, though was kinda hoping nobody would actually say that!
I'm putting it into the local specialist, but what are the options other than outright replacement.....anyone????

jameslxdt wrote:sounds like the pump unfortunatley

Just to let everyone who mught have a similar problem know;
Well I had it checked by the local Pug specialist here EuroCare and they identified the problem from the fault code which pointed to a faulty temp sensor. (shoulda guessed, since there have been posts about the same thing).
The magician reset the codes and it is as sweet as.
By the way, I emailed Diesel Bob and he buried my wastegate analysis pretty deeply. Said that the turbo wouldn't develop any boost at low speed so it wouldn't be responsible.
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Eurocar care in Derby?

Tiny Tim wrote:Eurocar care in Derby?

Nope, Eurocare in Burswood Perth WA. Can't reccomend them highly enough.

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Could be the engine temp sensor.

When mine went I got the same symptoms as the ecu thought the engine was cold and rammed in loads of derv.
More derv more revs.

Check it out first as it cheap to fix.

Steve

I had same problem of revving up whilst ticking over. It occured probably every day. Everybody suggested fit new temp sensor. Fitted 2 weeks ago. Only done it a couple of times since. Improvement, but not sorted (yet).