Hello everyone,

I have an interesting issue with my beloved x308 xjr (89k).

The car stutters quite violently under moderate to high torque demand. It feels like someone else is applying the brakes intermittently.
While this is occurring, the message "Traction Control Fail" flashes up, as well as the ASC function light. Note that the car is not actually breaking traction.

More recently this has also occurred under more mild throttle application on the motorway at 70 - 80 mph in 5th gear (no downshift). Also note that turning off the traction control does not cure the problem, but often, switching off and restarting does. The onboard computer is also not showing any permanent errors/DTC's.

Has anyone else experienced these symptoms? An ideas as to the cure?

 

There have been some additional developements since my original post:

upon taking it to the garage, the car threw a "gearbox fault, then went in to "limp home" and then stalled. Upon pulling over and restarting, everthing was fine again!

Not heard from the garage yet.

 

UPDATE:

The following codes were read:

P0730 - incorrect gear ratio
C1095 - abs pump motor - control module related
C1155 - Front left ABS sensor
P0121 - Sensor A circuit range performance - Throttle position sensor related.

 

So, have you resolved your car problems yet?

 

I'm afraid not, I had all the codes cleared and the battery replaced, but car is still intermittently misbehaving. Additionally the car gave me a P1797 code when I used my own code reader.
Going to have to bite the bullet and take it to an adult to have look at it!

 

I was having problems with my XK8, not the same as yours, but some misfire and cruise control issues. I sent the ECU to ASI for testing and repair and all my problems are gone. As these cars age it is increasingly likely that there will be component failures in the modules. The C1095 code in the abs is an indication that the solder connection to the abs pump is failing. This is often intermittent at first. That can be a DIY repair.

JagRepair.com - Jaguar Repair Information Resource

 

I did not see a comment about checking the battery and connections. Even while driving a failing battery or poor connection can drop voltage to some systems to the point that you get random codes.

 

Thanks for your response RJ237.

I should update the original post on how the symptoms have developed. The car now stalls after a brief stutter under any kind of throttle demand, albeit very intermittently. This is usually accompanied by the "engine fail safe mode" and TC fail messages.

Since the codes were cleared at the "jag specialist" the only recurring codes are the c1095 and the p1797 I mentioned previously.

Things I have tried :

Replace battery (but I have not checked main power connections) - no improvement

clean the throttle body connections and MAF sensor/connector - no improvement.

Replace the EMS power relay for a known working one - no improvement.

I should also mention, that back in January I had a similar stalling problem, which turned out to be the fuel injector relay - which is why I still suspect relays!

Additionally these problems seemed to coincide with when I took the car to a garage to jack up the rear end to have a listen to the diff. This is probably just coincidence though.

How much do ASI charge for that service?

 

For you is cheaper to buy a throttle body from ebay, a new one is around 250 pounds.
Cheapest ASI repair is 325 dollars.

You can try this too, they are in UK, and they gave me a quote of around 200 pounds http://www.bba-reman.com/content.asp...e_body_failing

 

Thanks Flay.

Indeed, I described the symptoms to an ex Jag mechanic on the phone today, and he said he doesn't even need to see the car: it needs a new throttle body!

So in summary: MOT day on Thursday, it needs a new ABS module and a new throttle body, maybe even some tyres - could be an expensive week!

 

You do not need a new abs module. There are rebuild services on ebay. I don't know what they charge in England, but it's $50-75 here.

 

Understood RJ.

I will update this thread when I make some progress.

 

There is a large electrical connector for the ABS module. This can get dirty/corrode inside; suggest take apart and clean. Remove left front abs sensor, clean and test resistance; should be close to 1 ohm from memory. These problems can cause the gearbox error codes too. The codes you are getting do not seem to fit with those that other members report when their throttle body fails. I would exhaust all other avenues before replacing TB, as they are about $2000 new, and second hand ones are likely to fail soon.
Keep us informed

 

Many thanks fredd60.

I preempted you on that (at least partly). I cleaned the connector with some contact cleaner yesterday eve, and touch wood, ABS light has not materialized since.

However, the plot has thickened somewhat since yesterday. On the drive to work this morning I got "GEARBOX FAULT" and yellow light. So I was straight down to my local Jag man (different one this time), to have it diagnosed. The following code was present: P0740. The Jag guru informed me that this is most likely to be the PCB within the gearbox (electrics pack) - £478 to replace all in.

My dilemma is that bearing in mind the earlier P0730 code (He also told me this is the code of death), do I now go ahead and spend money fixing the current issue?

Has anyone had any experience of DIY ing this job?

I am also baffled as to how all these issues have occurred at once. It seems unlikely that a transmission issue would occur completely separately, but in coincidence with the stalling/TB issues! The jag guru's opinion is that they are unrelated; it is possible I suppose.

 

I only had TB issues like those you describe on my XJR; but before I spent the money to get mine rebuilt, I decided to try one last easy and cheap fix which I got here on the forum: I cleaned the throttle body thoroughly, and put cable ties around both sensor connectors. That fixed it. No issues at all in the last 4 months. Clearly, normal engine vibration was playing havoc with the integrity of the connections. Good Luck!

 

Seems you've got a couple of things to look at, going by the codes
730 gearbox - if you can get under the car, check the electronic loom on the side of the gearbox, it's a twistloc and there's a seal in there that fails, leading to trans fluid creeping up the wiring, this can lead to glitches, you can buy the seal from Mercedes Benz for a few quid.
1095 ABS - this is another common fault - the 2 solder points are corroded and have lost control with the module. Easy fix I've just carried it out.....see here
https://www.jaguarforums.com/forum/x...17/#post753352
Abs sensor- could need a clean of the sensor face and rotor ring on the back of the hub, it can be tested along with the link lead, if goosed a secondhand part is a cheap fix
The TB - this sounds like worn tracks and the trigger for limp home mode. It will get gradually worse as the signal gets more intermittent - a refurb or replacement TB is the answer here.

Hope this saves a few quid and clears up what they usually mean. Some people like to replace parts, I like to fix them, keeps the system integrity and no need for reflash.

 

There are three connectors on the throttle body. DENSO gold plated the male pins of the connectors on the Throttle body. Jaguar used tin plated female pins in the connectors that mate to the Gold pins. There are Service Bulletins on the problem. Disconnect each connector, clean both sides with contact cleaner and coat contacts with dielectric grease

See if that improves the problem

 

I must say, I did try that a couple of weeks back and the stalling hardly occured since (while I have been driving the car), however, my father informed me that it stalled in reverse gear last week - I have never experienced this.

First things first, the car is now overdue for its MOT, so need to get that ABS module sorted: abs light = instant MOT fail these days. (Unfortunately the contact cleaner only worked for a day)

 

Just some additional thoughts: Could a torque converter lockup malfunction also be the cause of the stalling? The P0740 code suggests that this is what is happening; if the coverter is locking prematurely, this may have the effect of a high load on the engine for a given RPM when the throttle is pressed -> stutter/stall.

I am thinking that replacing the Transmission electrics pack will effectivley kill two birds with one stone.

Your thoughts please.

 

have you checked the trans connector yet?