Hello all, sold my 03 XJR a couple years back and recently have been itching for another supercharged Jag. Found a good deal on an 03 STR with ~80k that needs work. Owner states the coolant hose under the blower is leaking (verified this when I looked at the car), and the car would act up past half throttle and throw a restricted performance message. Owner was honest about the car and it was in good shape other than these two issues which I have no problem tackling, but after test driving I'm thinking there is more to it and wanted some opinions.

At light throttle and normal driving the car behaves perfectly, shift into 2nd is a bit firm but feels good. No issues coming to a stop, car downshifts fine. At 50% throttle or more its a different story. The car shifts very hard and over-revs when shifting (let out around 5k rpm) - once you let out of the throttle all is normal again and car drives without issue. No check engine light or restricted performance light which leads me to believe a transmission problem. I can't see any engine/sensor issue causing a super harsh shift and over-rev like that but wanted to see if I'm missing something. I would actually have felt a lot better if a light or error message came on, the fact that it didn't is a worry.

I scanned the car and its showing the P0171 and also a P0111 (IAT sensor). My scanner probably wouldn't pick up trans codes anyway but it was worth a shot. My gut is telling me that the trans is toast and no matter how good the deal is I really don't want the headache of either sourcing a used/rebuilt trans or having it rebuilt by a shop. I know these ZF 6 speeds are not cheap no matter how you fix it. Car is probably not worth what a new trans costs and that's besides the other little jobs that need doing.

As I said, my gut is telling me to just move on but I wanted to hear if anyones had a similar experience and it was engine or sensor related.

 

Probably P1111 - which is a good status code.

P0171 suggests an air leak and they can upset a gearbox.

 

Thanks for the quick reply! Reader said P0111 (IAT Sensor Circuit...), I'm certain it was P0111 but it's just a generic scanner so who knows. The P0171 was definitely there.

How badly can the P0171 upset a gearbox? The car basically felt like it dropped out of gear and just revved when under a decent amount of throttle. How could an air leak cause the transmission to basically stop propelling the car? Hoping you're right and it can, but it felt just awful to me.

 

The PCM can't control the engine so the trans gets upset.

If you can't deal with stuff like this just don't buy the car.

 

Not that I can't deal with it, was just looking for opnions since I'd rather not dump a $3-4k trans in a car that's not worth much even if perfect. Car is pretty inexpensive and otherwise very nice, but not inexpensive enough to start replacing a transmission. I know the 6HP is a pretty tough trans, but when they go it gets expensive pretty quickly.

Thanks again for the opnion. Almost wish I could try to fix it before I decide to buy the car, but obviously it doesn't work that way.

 

If it helps any i had a couple flare issues in my 06 str. Same trans. I put about 600.00 in genuine zf parts into the valve body and filter and fluid. Reset the trans values and wow it is what i feel is like new. Never had codes but watched a lot of zf trans expert videos

 

Thank you, that is helpful. I think I'm going to pass on this one and keep looking. With all of the other work that needs done any trans work would pretty much make the decision to wait and pay more for a nicer car an easy one. Hard to let it go since these don't come up for sale often and it was pretty nice otherwise, but I can only take on so much of a project with everything else going on in life (other cars, hobbies, baby, etc). The coolant hoses is one thing and a day or so worth of work, but getting into the trans could quickly turn it from a nice little project into a nightmare if things don't go well.

Thanks again for the insight, appreciate the reply.

 

Yes I would service the transmission and try to get the car hooked up to SDD to check for deeper Jaguar only codes.
If it drives normal under any condition that is a good sign so maybe the transmission just needs some maintenance as Scottjh9 said above?
It could be something as simple as a fluid level problem especially at 80K miles.

Do your research and replace the sealing sleeve when changing fluid. They almost all leak eventually and will cause low fluid level eventually.
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