HDi turbo lag and engine rattle

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paulstow
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HDi turbo lag and engine rattle

Post by paulstow »

Just occasionally on my Xantia HDi it seems the turbo doesn't cut in for a few seconds. It then suddenly gets the message and all is well. It's happened when getting on the power after junctions etc, but also when overtaking from about 60mph. Feels like something is sticking - any ideas?
Unrelated, I have a light rattle which is evident around 2000 - 3000 rpm. Could be a valve, though it sounds a bit lighter weight - any ideas?
Cheers - Paul
RichardW
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Post by RichardW »

Paul,
The reluctance might be the throttle position sensor or the MAF - you might need to get it on the diagnostic computer to find out (but then it may not have recorded any faults...!). MAF faults seem to be common on many of the modern generation diesels (I wonder if they get gunked up by the EGR?).
Is yours an HDi 90? - if so the rattle at 2000 - 3000 rpm is well known, and seems simply to be a combustion noise harmonic/resonance in the engine. If it's a 110, it might be worth getting the cambelt checked just for peace of mind. Oh, and if it only comes on when it's cold - check the crank shaft pulley as these are known to break up anytime after 70k.
paulstow
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Post by paulstow »

Thanks for that. It's a 110, and the rattle is present when hot or cold. Does that rule out the crank pulley, or is it worth replacing anyway - the car has 100K miles?
I'll take a look inside the MAF and ducting to see if it looks bad in there.
Cheers - Paul
rossd
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Post by rossd »

There is a new school of thought about the rattling on the higher mileage HDi's. I was talking to a chap with a Pug 807 HDi a few weeks ago, and he had this rattle problem. A diesel specialist told him it was leaky injectors; they can start to weep as the fuel is constantly behind the injector at full pressure all the time the engine is running (Compared to the older XUD where the injection pressure builds only before injection). The rattle is caused by the fuel getting into the cylinders and combusting early causing a knock or rattle.
A new set of injectors cured the problem for him. The only trouble is, they are ar from cheap.
paulstow
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Follow-up to Xantia HDI turbo lag

Post by paulstow »

I posted the question regarding turbo lag sometime ago and spent somewhile suffering the problem and have not since been active on the forum.

However, the fix was pleasingly simple. The turbo wastegate is controlled by a vacuum valve located towards the rear left of the engine bay as you look in from the front. A pipe then runs along the engine and connects with a plastic elbow which plugs into the vacuum pump on the end of the camshaft ( right hand side, looking in from the front ).

After 100K miles or so, the small diameter part of this plastic elbow was gunked up with oil, hence no vacuum and no turbo. Clearing it with a airline or just a piece of wire will do the trick.

Now done another 50K miles without the problem recurring. Mind you, I do need to do a belt change and there's a hammering noise from the fuel pump area which sounds like a regulator or something has packed up. Still, can't complain at that given otherwise troublefree motoring :)
Jez

'00 Xantia 2.0HDi
'01 Dispatch 2.0HDi
'01 Jaguar XKR
'68 MGB roadster
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