Any suggestions on how to trouble shoot this one?

 

First off have you an OBDII reader, if so the codes it pulled? If not, it'd be a good idea to get one and post what you find?

Any symptoms? what's it doing? any engine warning lights? is it attempting to start and drive? is there a restricted performance warning?

Any info at this stage would help immensely!

 

Thanks for post, I'll get this info and post ASAP....

 

Hi Sean,
Apologies for the delay on getting back to you. I had to go out and purchase a OBDII reader to obtain the fault codes.

XJR V8 SUPERCHARGED - Chassis # SAJAC15N82MF44364
There were 4 as listed below:

P1797 - Neutral Switch Circuit Malfunction
P1643 - Fuel Pump Monitor Circuit Low Input
P1637 - Can Link ECM/ABSCM Circuit / Network Malfunction
P1638 - Can Link ECM/INSTM Circuit / Network Malfunction

Any symptoms?
Left hand engine bank is not working.

what's it doing?
Engine only running on the right hand side, the LHS bank is not working at all... Also the Rev counter will rise once and then stay stationary.

any engine warning lights?
No warnings but the dash instrumentation is listing the following:
Failsafe Engine Mode
TRAC Not Available
ASC Not Available

is it attempting to start and drive?
Yes it will start and drive but only using the RHS engine bank.
Hopefully this helps and thanks in advance if you can offer any assistance.

is there a restricted performance warning? Yes

Thanks
Gareth

 

Sounds like the dreaded chain tensioner failure. Pull the offending bank valve cover and see if there is still a chain connecting the intake and exhaust cams.

 

How are you so certain only one bank is working without anything specific like specific cylinder misfires that are only on one bank?

Is the car driveable since you said its running?

 

Thanks for the reply's folks, yes the car is still drivable but i will check the chain tensioner even though I doubt that is the issue because compression seems ok in LHS bank. The car was taken to Charles Hurst (main Jaguar dealer in Belfast) they said they would need to fit 8 ignition coils/packs at roughly £2000... I didn't go ahead and swapped the coils from LHS to RHS myself and the RHS still worked as expected. Was also talking to another jaguar expert and he said it might be a wiring problem. He also said it may be a faulty ECU, I was hoping that someone could figure out the codes that i posted earlier. again help figuring this out is appreciated...

 

Also to add, if engine left running for a few mins, RHS Bank is roasting whereas the LHS is cold. So this is why I'm thinking its total LHS failure.

 

somewhere in the foggy recesses of my mind, the XJR can go into limp home mode if something's amiss with the gearbox cable adjustment. It might be a case of tightening the two nuts that hold it tight under the selector. First I'd check there. You'll have to remove the centre console which is a half hour job of gentle disassembly. Tighten if needed, and pay close attention to the original place the cable was, it's set to a switch and if out of sinc you get these faults. Next disconnect the battery at the neg terminal for 20 mins. This erases the car's memory.

To remove the console use the search function. Let us know if this cures it.

Have you checked fuel pressure?

TRAC/ASC can be due to a number of things, the all time top 3 are...
1. weak battery
2. dirty wheel speed sensor
3. ABS module faulty, these can be fixed a lot of the time, again forum search will bring this up.
But, these can be scrolled with the misalignment of the already mentioned gearbox cable/switch. If the cable is in the wrong place in relation to the switch, any number of faults can be tripped.
I doubt the dreaded secondary timing chain tensioners, the noise would give that away, and your car seems to be a late one, what's it's manufacture date, failing that it's supply date?

Don't take another month to past back eh! lol!

 

What about those network failures?

Presuming the mechanical side is fine, the LHS, like the RHS only needs two things to run. Spark and fuel. Which one is lacking? And then .... why.

 

IF you actually have one bank not firing, and the timing chain is right, then the only things that iare not common to the banks is the ECU or the wiring. I would look first at the negative common connection for the ignition coils, which is shown as a yellow wire with a green stripe. A splice brings the wires together before running back to the ECU.

You don't suppose the timing chain is brioke, but at a position that allows compression?

 

QuadManiac laid out a really good procedure for testing the coil circuits sometime in the last couple of days.

 

I doubt the coils themselves are bad, since four failing at once would be unlikely. The interconnect wiring is the issue.

 

Thanks folks, lots of good suggestions here.... Will investigate them all over the next week and report back on my findings.... Hopefully will get this sorted soon...

 

Agreed. But, that's what the procedure was addressing in terms of "weak" circuits. Not everyone would think of doing it the way that was described.

 

Hi Folks, sorry for the long wait in replying to this, it was the secondary timing chain tensioners, the chain was actually broken so thankfully the issue has been identified. Thanks a million folks for all the suggestions really helped.

Another question for yoiu guys, is there any place that tools can be hired to set the timing for fitting the new chains? I'm looking to hire instead of purchasing as it will be a one off procedure hopefully.

Thanks again guys!!

 

Am I wrong if I think that the compression numbers could not be good if the valves are always closed? Only the negativ-positiv pressure is jumping in cylinder in that case except that there are bend valves and the cylinders are not sealed.

Anyway, this problem is forcing that the tensioners are weak and dangerous parts in the engine after a mileage.

 

I can suggest the J.E.C.

Jaguar Enthusiasts Club, Classic British Cars, Jaguar Owners Club, Jaguar Tool Hire, The largest Jaguar Club covering all models including E-type, S-type, X300, XJS, XJ, Mark 2, XK8

Maybe speak to Annie Jenkins about the hire of a tool set, alternatively, you can buy the set on ebay for around £250, and sell them on when finished, they're a sought after set for obvious reasons!