Car in question is an 2002 L322 4.4 V8 with the BMW lump and a ZF Autobox.

Now when you driving and you take your foot off the accelerator the revs will instantly drop by around 500-1000rpm with no change to road speed.
When you put your foot back on the accelerator the revs will instantly rise back up to where they should be.

Now I've driven a few autos and none of them have done this before. Is it normal to have this much 'slip'?

I only ask as it's something I've questioned for a while and recently the box has started giving grief. The oil and filter has been changed and appareantly the old oil was black and smelt burnt. I've reccomended the oil be changed again because you only get 4-5litres out at a time and the box takes 10litres. I'm currently putting 2+2 together and thinking the torque converter has had it.

Bailes.

 

Oil pump in the box goes knackered, it's a machine fit into the case, ruins the case - just had 2 done @ 2k a piece

 

Very difficult to diagnose autobox faults without driving it, but, if what your saying happens over 30/40mph then is sounds fine.

All autos now have torque converter lockup, this is where the turbine and impellor become equal in speed. Something that the older autos never did, hence poor fuel economy in automatics as you always had an over drive scenario of engine to box.

With lockup the engine speed becomes 1:1, what the crank delivers is what the box receives, usually a drop of about 500-1000rpm

n.b. lockup only occurs when you back off the throttle i.e. very light cruise, as soon as you accell again it instantly releases.

 

Ahh... See now I always believed the only time the torque converter 'slipped' was during gear changes and pulling off from stationary!
Learn something now every day.

From what I can gather (I'l be going in it on Monday) he said the gearbox is grumbling the car feels like it's labouring constantly. He said changes at speed are slow and quite jerky.

 

It should be silky smooth to shift, the torque converter slips constantly except on lock up.
Probably like Ricky has said, internal failure.

 

Defo oil pump packed up, there on long life
Oil and the box oil cooler is too small to keep the oil in a good condition for the length of time it's supposed to last, google it its a well known fault on them , there shit!

 

there's a guy on one of the land rover forums who rebuilds these boxes for fun. he only charges for the parts used.

Here's one of his posts - http://forum.landrovernet.com/showth...earbox+rebuild

 

Small world
My x5 came up with trans fail safe this morning and is grumbling like a bitch!
After a couple of hours researching stuff it looks like its replacement box time

BMW quoted £6.5k for a new replacement or £3.5k ish to get it rebuilt, let's see what warranty direct say about that

 

Cheers for everyone's input.

Been out in it today.
It generally drives and changes gear superbly!
But when your cruising at a certain speed and you just prod the accelerator a tiny bit you get a deep rumble coming from mid to rear of the car and the revs jump up and down by about 250rpm.
It doesn't happen when it's cold, only once it's warmed up.

There's also serious vibrations coming from the rear of the car over 70 which have only just started.

 

If you're not already signed up, do so on that website above, post your problem and you'll find there's no shortage of people who will offer their opinion. Some of them really know their stuff

 

Oh dear, does the 320 sei petrol auto have similar issues? 2001 plate

Mate picked one up last thursday. It was fine on the test drive but never went above 40. On the way back we stopped and he said it kind of grumbled a bit and the revs dropped down.
So from what mark says the rev drop is normal, grumbling is not.

He said he has not noticed it since, but not used the car much either.