Ever since I got my new engine I have been noticing this judder. I had my engine control module reset but I feel it is a transmission issue / powertrain issue. The jag service mechanic did not reset my Transmission control module.

When im driving fairly fast on a high gear (4th to 6th gear) and then coming to a fast stop I notice that when I am near stopping speed the car will shift into 1st. Half of the time it will not shift into 1st on stopping.

This happens not always but many times when coming into a stop from a higher gear. This makes me intentionally release the brake a bit just to make sure the car stops smoother. When the car gets into this gear (maybe its 1st gear but I heard the XF ZF6HP doesn't shift into 1st and stays into 2nd) then it feels as if it bangs into the gear and there is a short vibration of instability.

When I am in 2nd-3rd gear and come to a stop then it stops as expected and doesn't shift into that 1st gear. I am not sure if it is 1st gear because it makes the car feel so light as if it is in neutral...as if there is no resistance.

Also another issue that might be related is that when I first start up the car and turn my steering wheel sharply I get steering wheel judder which smoothens out after a couple of seconds.


Are these characteristics normal for my car?

 

My car does that same thing, both the tranny and steering,

I consider it normal for the tranny and no real issue on the steering.

 

A downshift "kick" or bump when coasting to a stop under light braking is normal for the ZF. It should not be in first gear though as the programming selects second gear as the default start up gear. The transmission only downshifts to first as you take off if you stand on the gas pedal. You can check which gear it selects by default but using the paddle when stationary to try and upshift, the display should show 3 briefly before re selecting 2.

I have not experienced the judder you refer to. Are you "dry steering" trying to move the front wheels while stationary? If you are then judder is possible depending on the tire grip, road surface and any Ackerman effect in that if Jaguar designs in less than full Ackerman, which is very likely, then dry steering requires one or other of the tire contact patches to scrub as the steering angle changes.

If you get judder only when dry steering and not if you are in motion then I suggest you just stop dry steering unless you are on a smooth concrete parking floor or in snow.

 

You have a version of the "Lurch". Very well know for the 6 speed ZF.

I had the TCM reflashed and it's now pretty minor in my 2005 STR but as others have said you can "drive around it" if you know how.

Have you read this?

Jaguar S-Type Ownership Experience - The ZF LURCH Fault
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Yes I can confirm it is not going into 1st gear as I thought but yes it does feel as if the ZF transmission is disengaging from the drive as talked about in the lurch website. I can confirm that its not going into first because I felt the same thing when using the paddles and stopping in '2nd gear'.

SHT

I hate the lurch because it was even worse before and I got my TCM updated to the latest software. I then got it reset again with the power train control module as I heard that you need to get both reset in order to fix the lurch. Then I got a new engine...in which when getting it I asked the jaguar mechanic if he reset my power train, engine, and transmission control modules... he told me there is only 2 modules and he only reset the engine as the transmission is not needed.

Is reset the same as reflash?...not sure if they are actually reflashing the software or reseting the modules (from what they have 'learned' on my driving habbits).

With regards to my steering wheel it is at slow creeping speed while turning sharpely that I feel the vibration in the steering wheel as it sort of 'skips".

 

Your steering effects are normal in a modern car with modified Ackerman geometry. My Alfa Romeo has no Ackerman and steers oddly at low speeds and tight angles. Normal at slow speeds, it's the tires scrubbing.

Transmission "thump" is a ZF characteristic and nobody can fix it. ZF likes the tranny to select second just before you stop in case you change your mind and step on it again. The 8 spd is much better in this respect.

Re flash and reset mean the same thing in this context because the mechanics service computer will be loaded with the most current software approved for this engine. I'm surprised they didn't reflash the tranny ECU also as they did for mine when they fit the new V6. Both ecus were re flashed to be current and it was noticeable that the transmission software had been reset as it has been re-adapting ever since. Technically it is correct that the transmission ECU did not need to be re flashed but why not since the car is plugged into the computer anyway?

When you take it back for correction of the noise and replacement of the engine cover (tell them about that problem over the phone as I'll bet the new cover has to come from the UK) you could ask them to reflash the transmission ECU for you. Under warranty of course!

 

Yeah that's what I will do. I hope I don't have to visit service any more after this...I am getting tired of not being able to have a worry free car.

 

On the S Type the TCM reflash is a software update. Applied by the dealer.


I don't know if you can reset the TCM without a dealer tool of some kind.
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Yeah I had my software update earlier couple months ago. So I assume its on the latest software. This did fix the harsh stops and made the downshifts less harsh when slowing down.

Today while driving I did not experience any issues with the transmission...it was pretty smooth and no lurch. I am thinking the software is learning my driving style. I think when I drive more hard then the transmission will start shifting hard and create the lurch effect...

I will do more testing but I was happy with my drive today.

 

Good to hear and lets hope it stays that way too.


The Lurch is a pain and I have learned to drive around it most of the time but every so often when coming to a stop it gives a good clunk!
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