2001 XJR 4.0 sc.. The other day the gear change seemed a bit harsh but then drive ok. The second start up was ok, but at about 50mph said “gearbox fault”, then when I got home she wouldn’t engage into reverse or even D. I turned ignition off, then started her up and all was fine. The next day I started off and all of a sudden she lurched forward and I didn’t need any additional gas, it was like she was in failsafe mode. I cleared the codes but she still kept too high revs. I’m certain it is not MAF , (which is indicated by P0101) , TPS or AITS as they’re new. TB has all been cleaned and reset.
Now P0715 says input turbine speed sensor circuit? I cleared it and it’s not come back, but “engine failsafe mode” has.
Do you think that the turbine input sensor is easy to replace? Someone told me the actuator plate may need changing. Is this a cure? I’m puzzled as to why this would cause high revs.
She only goes high revs when I start to drive off, not when she’s just sitting on the drive.
Help most appreciated!

 

Might get more of a response if you tell us what gearbox is in your car and what MY it is?

 

It is certainly good when a posting includes that information and it may get
more responses that way. Julia has a 2001 Jaguar XJR 4.0 sc according
to her profile.

 

Hey thanks! Yeah she’s. a 2001 X308 XJR… 4.0S
supercharged

 

I would clear all the codes and maybe perform a hard reset. When you drive it, see what code(s) occur first.

 

Bob, this is not the first time you have posted this when the OP has included the information in his post.

 

Bad maf sensor could make harsh shifting but gearbox fault
And car going forward by its own it might be the drum
​​​​However I would check the transmission fluid
Liqui moly 1200 ATF suitable for merc W5A580 transmission
5 liter is for 60$ in Amazon

 

Wow! Thats a nice price for tranny fluid for these cars. Are you running
this fluid in yours SilverJag?

 

Oil is fully at correct level.. where is the turbine speed sensor ? Would it create high revs? and is it a difficult fix? cheers

 

I'm actually running amsoil multi atf the one equal to lt71141 I had 6 liter left for my other car so I filled about 3 quart in my zf5hp 1 year now and thankfully everything seem to be fine . The liqui moly1200 is also suitable for zf5hp and the xjr merc transmission the merc transmission have limited fluid choices and the OEM I believe 25$ per quart

 

When I posted this, there was NO car info. If you look, you will see that the post was EDITED. (I would guess to include the info?)

 

Please accept my apologies. I should know better than to accuse you of not reading all the details.

 

First stop for me would be the conductor plate

 

thanks very much.. do you think the conductor plate would cause higher revs? Is it difficult to replace? Cheers!

 

I don't always get the details right but I did re-read this one several times to try and guess the MY and gearbox.

Keep me on my toes though, I do post in the wrong section at times!!!!!!

 

Conductor plate can put the tranny in limp mode which I believe limits it to 3rd gear.

Replacement is pretty easy, just disconnect the multi pin connector, drop pan, unbolt valve body, remove solenoids, swap plates, and reverse. Few hours max

 

Ok cheers!
I disconnected battery.
I swapped the MAF. This was quite newish with 12,000 miles on it which I had kept as a spare but suspect.
Before I did that I cleaned it with a cotton bud with MAF cleaner and sprayed the plug. I then saw this MAF had the diode slightly bent , maybe even touching the plastic protector. I carefully straightened it using a thin screwdriver (not touching the end£
plug the MAF back on, but left it unplugged. (This is a tip from a mechanic in the scrapyard when I was younger) started her. She ran lumpy and angry without her MAF. Switched her off for 5 minutes.
plugged MAF in, started. EML still on, with fault codes P0102 and P0112. Cleared codes whilst running. Switched off.
Started her up. All fine. Have driven 5 drive cycles, taken her up to 75 no issues, so far, so good!
I can only think that somehow the MAF created a bad signal in the middle of the journey, tried to tell the ECU to go into “engine failsafe mode” or “restricted performance “ and made the gearbox module freak out. I’m hoping that it’s not a gearbox issue after all, but this was a strange phenomenon.
cheers and a good weekend!