Here's one for the rarely stumped collective..................


2008 A4 Tdi Auto.

When pulling away it seems to sruggle to rev so pulls off (relatively) slowly then after 0.5-1 seconds
picks up and away it goes. However, as it takes off the transmission seems to snatch, best comparison
is in a manual you are slipping the clutch for a second then sharply let the pedal go.
Much more noticable setting off up hill.
Gearbox fluid changed with genuine Audi gloop, no difference and nothing shows up when plugged
into diagnostics (Hella Gutmann Mega macs 42).

Any ideas ?

I don't pretend to know much about autos, but in the torque converter there is a stator which is there to give you the initial torque to get you going, it kind of kicks you along from a stop. Not sure if that it the case but that's the only thing I know that would give something like that symptom.

Something to do with a valve or restricted oil for first gear which is making it slip and then bite?

hope this helps, I hate autos

There's a possibility it's exactly what you said, the clutch is slipping then snatching

Are you sure it's the gearbox?

You state that the engine struggles to rev. Surely if a clutch etc is slipping then the engine would rev freely - just no or slow forward motion.

A lot of turbo diesel autos, limit the power from standstill to avoid putting too much stress on the gearbox. eg A BMW X5 3ltr turbo diesel I drove recently seemed very sluggish (initially) until vehicle was traveling at around 5-10Kmh - then the engine would 'wake up' and accelerate quite quickly for a vehicle of that size/weight. Owner said it was to avoid stressing the gearbox from standstill.

Maybe whatever sensors/etc that do a similar thing in your vehicle are misbehaving. Or, it could be something wrong with your turbo - stalling/sticking at low revs and then working once more exhaust pressure it available. The gearbox snatch/judder could be because of the extra power which it's now having to deal with.

David

Just be thankful that it's not got a cracked head

quote:

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Originally posted by feckn7
Are you sure it's the gearbox?

David [/quote


Nope, and never directly said it was

Was using an analogy to try and describe the symptoms. Fully expected some to say"Change the gear oil"
as that is normally the first thing to do when autos don't change right. So it was a pre-emptive thing. Was
done at last service a month ago.

Almost certainly engine/turbo/electronic related, I just have no idea how the electronics control take off etc.

Was hoping someone would recognise the fault and say it's your figglewidget or whatever.
BTW, it's not mine but a customers. Going to direct him to an Audi specialist.

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rhinopower - 4/4/13 at 02:03 PM

I had same problem before, turned out to be a cracked gear.

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