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Discussion Starter #1
I wonder if anyone can help me?... Although this problem is quite hard to describe:

I have an Alfa 159 Ti 2.4JTDm. It is 4 years old and in it's life it has suffered endless episodes of engine hesitation which, even after a cylinder head replacement under warranty (not convinced why Alfa thought it was this) has never fully disappeared. But the nature of the hesitation certainly has not been the same over this time. The one thing common to all my hesitation events has been that it always occurs when you're hovvering between acceleration and deceleration.

Recently, I have started to develop a new theory and wonder whether the hesitation that I still have is not an engine management issue or some problem with the EGR, but maybe instead from gearbox 'slap'...

What I mean by this is the idea that within the gearbox there might be quite a finite 'zone' of non-cog contact as cogs transition between accelarating (the cogs leading edge being driven by the engine) and decelarating (the cogs trailing edge being arrested by the slowing car). So my thought is that the hesitation is in fact simply the gearbox "taking up the slack" as it moves between these two states. Is that possible or understandable? Or am I going mad?

I also now have quite an interesting noise coming, I think, from my gearbox when I go between acceleration and deceleration and vice versa, i.e. if you are pootling along in a low gear (e.g. 2nd), then gently accelerate then decelerate then acelerate, etc, I get this odd squeek appearing on each transition. I have convinced myself that it is not the suspension because I now hear it for a very brief moment when starting the car as well. I'm beginning to get nervous and wonder if anyone has the slightest idea if my explanation vaguely fits an issue that is known or might need attention.

Any help or thoughts would be appreciated.
 

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Mines a bit similar. I get the squeak when starting and on deceleration. I've always thought it was the suspension but might be thinking gearbox now. I'll be watching this thread for any developments.
 

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I would have thought any play in the transmission would be more likely to be in the differential rather than the gearbox.
 

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It is for 99% the worn dual mass flywheel. Had the same on my 1.9JTD after about 150k.
Replacement is very expensive. Sorry to say this.

Cheers tomsa
 

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Discussion Starter #7
Thank you for some very interesting possibilities that I would never have thought about... Flywheel, engine mounts and differential. By the way, tomsa, if it is the dual mass flywheel, have you any ideal whether this would eventually be a catastrophic failure or whether it will be something that just progressively gets worse?
 
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