I’ve had a 2010 XFR since 2012 and had few issues with it but now having an issue where sometimes at the the point of hard acceleration, rather than down-shifting and accelerating away, the car seems to drop into neutral. The gear selector is in Sport mode at the time. The only thing that seems to resolve the issue is to pull over, switch off the engine and re-start.

Any ideas what’s wrong and how expensive it might be to put right? I’m not a mechanic so would probably have to take it to a garage.

 

How many miles? It could be just low fluid? This might be a good time to do a full service of the 6 speed ZF?
Otherwise I would hook up SDD and see if it can retrieve any codes.
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100K miles. I should maybe have mentioned it’s the supercharged 5 litre. Recently serviced.

 

I'd start with a transmission service, fluid and filter change. Hopefully you won't find a bunch of metal or too much friction material in the fluid and filter.

 

Get a good code reader on it and see if it is throwing any transmission error codes.

 

A quick update for information. I took the car to a Jaguar dealership and they told me the car needs a new gearbox. I shouldn’t be surprised really but had hoped for a better response than a lazy swap-out approach.

Speaking with a chap who works on these ZF gearboxes, he immediately said the problem is likely to be the solenoids in the mechatronic valve block. It seems this is a very common fault. He’s rammed with work for the moment so I have to wait a couple of weeks before he can even have a look but already he’s given me a far better response than the dealership.

 

I think to a dealer a gearbox is effectively a sealed unit. They _may_ do fluid changes but that would be about it. Good move going elsewhere.

 

Valve blocks are usually pretty easy to change. I changed out some piston seals on a Range Rover ZF unit once that had a common fault. It was pretty easy. Take it to a good transmission shop. All automatic transmissions can be rebuilt.

 

Agree with kansanbrit. Find a shop that works on ZF's they are common. The dealership has no interest in you or your car.
Post back with whatever second opinion you get. I bet it's not a total transmission replacement.

I have posted this a few times but in the US this is the place that has everything you could need to repair ZF transmissions or to do maintenance.
ZF Transmission Parts and Fluids
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if it has the zf 6 speed i had the exact same thing happen on my 06 str. I mean exact. After much troubleshooting and trans work it ended up being coils and plugs. Small high demand misses that the tcm picked up on. Eventually the nuetral flare will become worse and start doing limp mode. The flare is actually the convertor clutch disengaging as commanded by the tcm briefly. I saw this while driving and watching the control solenoid miliamps change as the flare occur. Fluid and filter change is a good start point. You might remember my saga club and the resolution thread

 

Looks a good site, I hope I can find something similar here in the UK.

 

Don't know where you are in Kent but Collier Street Garage in Marden are OK.

 

scottjh9 is 100% right about that!
It's a great point to remember too. I am surprised that you did not have miss fire codes?
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Maybe had P1000 so OBD monitors unset and thus unable to flag codes.

 

that is what made troubleshooting so difficult. No codes anywhere. The tcm picks up the small misfires but they are not severe enough in the beginning to set an ecm code. I found the small misfires by watching each cylinder misfire counter in real time using my older snap on modis. When it got bad enough it finally set a checksum code via the tcm. I finally figured out checksum is all the info the tcm sees and compares it to what it is expecting

 

https://www.jaguarforums.com/forum/x...-wasnt-282107/ have a read of this thread might shed some light.... https://www.jaguarforums.com/forum/x...t-read-222193/ this one too

 

Great discussion and very informative. Thanks for the links too, they make me question the need for new solenoids - reinforced by the Jaguar dealer advising in the service report that the engine felt a bit lumpy when it was started. I assumed this was an unrelated issue possibly due to wear but if the coils are not 100%?

 

I’ve not had the chap look at the car yet but there’s been a major development this morning. Just as I was approaching home from our local garden centre (luckily) the engine suddenly got VERY lumpy, displayed a “restricted performance” message, and produced what looked like lots of smoke from the exhaust.

Pulling over and getting out of the car I was hit with a very strong smell of fuel so not smoke but unburnt fuel. Code reader tells me I have no ignition on cylinders 2, 4, 6, and 8. Codes are P0302, P0304, P0306, and P0408.

I doubt 4 ignition coils have failed at the same time. Any thoughts on this and could it be related to the original fault of dropping into neutral or do I now have two unrelated issues?

 

Up to you but you have all the signs of injector failure. Was the smoke white and you had quite a bit of it?

I would plan on replacing the injectors on that side of the engine. Do all 4 of them. The coils are up to you and not a common failure but certainly would be a good idea in general. In my experience it will be injectors and since your in there and for not much more cost I would replace the plugs too.

Now this is another BIG issue you need to be aware of? Tons of counterfeit injectors and many other parts as well out there!
I spent a miserable 2 weeks swapping injectors, checking for spark, running compression tests, verifying fuel pressures. I finally listened to my tuner AND a Jaguar dealer mechanic and put my OEM injectors back in after having them ultrasonically cleaned and flowed.

Here are a couple of picture that hopefully will guide you when buying injectors. Note that my fake ones came in Bosch boxes (Bosch is the OEM supplier to Jaguar and I always try to bypass the dealer and go directly to who actually made the parts-if possible). I also find the Bosch part number in addition to the Jaguar part number.

It's so common here is a picture that Hella (Hella now owns Bosch) put out to help identify "real" Bosch injectors. It's a stylized H so it's more of a symbol than a letter.





Here are my OEM injector markings.




Here is how my fake injectors were marked. Not much difference but when you start looking you can see what is what!




Note the difference in that the zero's are printed more round and the OEM has more square looking zero's. The 939 number has the ellipse line touching the numbers. The OEM has a rounded rectangular box around the 939 and the line does not touch the numbers anywhere.
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Thanks for this. I am struggling a little though to understand how all 4 on one side would fail together, any further insight?