Hi guys im a new to owning a Jaguar xj8 4.0 v8 1999 model 58k mileage. I normaly prefer the german cars v6 v8 etc so new to this tyoe of jaguar xj8 sovereign model although my father purchased one brand new back in 1999. Since iv have bought this car iv experienced many issues, mainly restricted performance issues. iv replaced 3 coil packs so far seems to have made the restricted performance error dissappear, so running super smooth bare in mind everything is orginal since 1999 nothings been changed other than a throttle body. I only use v power so the engine can run at its best, so i decided to do a resonator delete i had surge protection on the battery. Since i had did the res delete is come up with a gearbox fault code issue, in reverse its fine neutral fine park fine manual shifts fine, so i have diagnosed it today and has some codesPo790 mode switch malfunctionPo763 shift solenoid c electricalP1647 heated oxygen sensor control module bank 2 open/shortedP1341 cam shaft postion sensor 2 circuit range performance.I have tried a tcu ecu hard reset still the same i have plugged in few different types of obd scanners to see if i could earse the fault code but the gearbox fault error stays.Not too sure on what exactly should i do first so i could save some moneys. I have it booked in this Friday to have a major service.Any help any advice would be great.Thank you

 

could it be that someone forgot to plug some things back while doing resonator job?

 

Hi
Thanks for your message.
for me todo the resonator delete all that needs to be done is to protect the battery.
I wasn't there at the time of wielding
May be had a bad earth contact, im unsure. But before the vehicle went for the res delete I had a misfire i replaced the coil pack after the exhaust job.

 

On the transmission do no push or power through a gear change as this could cause further damage

There is a defect in the pressure regulator up to certain production # that can be resolved with the " Transgo Mod "

This requires removing the transmission pan and reaming up a size on the pressure regulator port on the vavle body

To know you have the issue some others would know better

If it is just a defective shift solenoid no big deal as well

But the main point today is to not push the transmission hard

 

lets don't enter dark topic of failed transmission yet, all those errors are electrical in nature thus or something is not plugged back or got cables burned while welding

 

hi thank you for your reply much appreciated.
To be honest its happend on the weekend and I haven't used it much roughly 5 miles a day.
when in drive it don't move i have to give it some even its really slow moving until I get to 30 mph I let go of throttle and just cruise .
when plugged in the computer the error won't erase. Shift solenoid c electrical.
before resonator delete it was fine.. just had restricted performperformance to multiple minor reasons. I protected the battery and had my colleague to do the wielding unsure whether he earthed it correctly. Soon as job was done gearbox fault code along with restricted performance I replaced a coil pack restricted performance went away left with permanent gearbox fault message .
thanks

 

Its definitely not a failure transmission as before job was done its was great so much so that I wanted todo an resonator delete . Any how definitely an electrical issue . May b bad earth connection inorder to wield. Max 2 3 mins of wielding.

 

The Mass Air Flow sensor is actually 2 . one for for the transmission ECU and the other one for the engine ECU

This may be for the throttle position sensor as would have to look

Both these were in the area of the resonator

 

I agree, always connect grounding point at nearest welding job....so, always disconnect battery !!!!

 

Hi yes definitely used a surge protector on the battery but left the battery plugged inn.
The only thing that I have forgot to mention was I sprayed wd40 underneath inside all wheel hub brakes etc had abit of surface rust.
then came up with a shift solenoid c electrical.
unsure if any of the wheel sensors or abs sensor etc are connected to the gearbox .