Engine Stops

[springelec]

Hi Everyone,

It's been a while since my last posting because I've been trawling the net for a nice XJR.

I bought one about six weeks ago, a late '99 with 90K miles and have been testing it for bugs ever since. Overall, the car is fabulous and I've enjoyed every minute. All those members that advised getting an XJR rather than an XJ8 were absolutely right and I would recomend the same.

The chassis number confirmed it was a late Nikasil model, but I had it leakage tested before purchase which confirmed it was OK returning only 17.6 litres/min. From my own research, the car needed to return less than 20 litres/min for a really good example, so I was happy.

The XJR is brilliant in every way, but its best feature is its acceleration. My XJR makes my wife's XK8 feel positively pedestrian by comparison and is closer to my bike than any other car I've driven.

However, it does have one reoccuring bug which tarnishes it a little.
About three times over the past 500 (ish) miles, the dash will show ABS and TRAC failure and the car drops into limp mode.

The accelerator has no effect and the car chugs along at 30mph. Consistant with this 'feature' is the engine idle speed increases to about 1500rpm. Despite this problem, I have cured it every time by switching off the engine for a few seconds and starting again.

Some how, starting the car again must reboot the electronics and it's fine for another few tens or even hundred miles. Has anyone any clues what could be wrong ?.

Thanks

Springelec

[joejag308]

Springy....... Has the throttle body been done? a FREE recall.......... ring the main agent and ask quoting your vin number.......otherwise get a diagnostic check done.......Joe

[paulbarrie]

Hi,
I've had this issue myself and it seems to be an issue with the battery. I do very short trips. After recharging the battery evrything seems to rectify itself.

Hope this helps

Paul

[daveji]

First thing to do is to make sure the battery is fit,and there is not a cell on the way out.
If the battery is "drop tested" it MUST be done OFF the car,or the electronics WILL be damaged.
If the battery is fine the ABS module is suspect and a scan will reveal the appropriate fault code if that is the case.
Experience shows its usually the battery,the voltage at the ABS module drops below the minimum 9.3 Volts and the ECU triggers the fault messages you describe.
Mine did this,except it was more transitory and I did not get the "limp home" mode.
David

[springelec]

Hi Joejag308 & Paul,

OK, spoke to Hatfields Jaguar in Worcester and they confirmed my XJR had no outstanding recall's against its VIN number. However, they have invited me to drop the car in for a diagnostic check to see if there are any residual error codes stored in memory.

Apparently, the car's software will store error codes to allow intermittent faults to be found and diagnosed. I watched an old video from about 1998 on Youtube a couple of weeks ago and this fault detection detail was confirmed by the then Technical Director who took part in the video promoting the 'new' X308.

Although not the greatest fan of 'fly by wire' cars, I'm quite impressed the Jag electronics and software engineers actually had the forethought to include this detail as a future diagnostic tool in the X308.

However, its inclusion could also be read as a disturbing admission of the cars' temperamental nature and unreliability. Another example being Windows 95, 98, 2000 etc, all of which also included built in software diagnostics to inform Bill Gates and his crew when Windows had crashed. Being an Engineer myself, I can appreciate the pros and cons of these tactics.

Thanks for the battery tip Paul, but the car starts first time, every time, and doesn't need charging. I am therefore struggling to understand the link between the car stopping and what would appear to be a perfectly healthy battery ?. If you've got any more information to support this tip, I would be happy to discuss it.

Thanks

Springelec

[springelec]

Hi Daveji,

Thanks for this advice. It should be quite easy to check the ABS module. I believe its the block with the pipes located near side front ?.

If I can find an electrical connector to this unit, I'll investigate with my DVM and look for any suspect voltages.

You made an interesting comment about 'Drop Testing' the battery. I am familiar with this technique and is used to flush out a dodgy cell. The technique allows high discharge current to flow through the battery. Any cells on their last legs will present a higher resistance compared to their neighbouring cells causing more heat to be generated in the electrolyte. Under heavy load, i.e. a drop test, a healthy cell will effervesce, but a sick cell will boil. ( A heavy duty screw driver usually does the trick)

However, this technique is usually used to confirm a battery that is already suspect. I have no problems with my battery and it isn't under suspicion, even though the car stands for up to a week without being used.

So to echo my reply to PaulBarrie, whilst I don't understand the link between the engine stopping and an otherwise healthy battery, I'm willing to discuss to understand more.

Thanks

Springelec

[paulbarrie]

Hi Springlec,

Yes my vehicle also started first time. I have a simple brain and don't understand any of the whys and wherefores but it did seem to be the answer.

Paul

[Brakebuster]

the TB replacement was NOT a ' recall ' , and as such will not show up against the VIN when asked

you have to be specific and tell them that you think you have problems , especially engine cutting out at motorway speeds then restarts , and does the TB need looking at,

they will then look at you VIN and see if
1, your VIN qualifies for any TB work ( could be replacement or simple ecu flash )
2, has the work already been carried out at any jaguar dealership, as a record will be held

if the work hasnt been carried out, and you VIN qualifies, then they should offer to book you in

if you just ask about recalls against your VIN, the TB will NOT show up in their searches

as a rule of thumb, any car after 1999 will NOT need the TB replacement... its mainly AJ26 engines of before 1999......

this includes the XJ8 , XJR , XK8 , XKR, Super V8 Daimler and possibly some very early S-Types ,

hope this helps
BB

[springelec]

Hi BB,

I've printed your notes and will show to Hatfields Jaguar when I go in to discuss.

I'll keep you posted.

Thanks

Springelec

PS: Did I mention I get about 24mpg, which I think is fantastic from a V8, 4L Super charged monster ! !

[Brakebuster]

you car being a late 99 one will have the AJ27 engine, and the revised TB fitted during production

the most you will get against this particular car is possibly an ecu flash for the TB, but you may not even get that if not required

i would let them take the codes from the car and give you a plan of action to rectify it,

a duff battery can cause erroneous codes to be thrown on the dash display , if its the original Jaguar battery, then it needs to be changed for a new one, as its getting quite old for a battery, and starting the car isnt an indication of its condition, and the vehicles electronics are very sensitive to voltage drop etc ,but if your sure its good, then you may have trouble with the gearbox or ecu

sometimes the gearbox loom plug can cause problems ,

BB

[springelec]

Hi BB,

Worthy notes indeed, although your comments about battery sensitivity is a bit alarming. I'm beginning to wonder if the battery is a bit of a red herring and the battery related problems you describe are more to do with tired connectors.

Given a car's electrical system is only 12V, it's very easy to lose voltage down cables and connectors especially when the car is ten years old. It is a fact that summer/winter and under bonnet temperature cycles cause electrical connectors to go soft given enough time. Throw in a bit of seasonal corrosion and it all adds resistance to the electrical connection and hence an unexpected volt drop.

I agree with your comment about letting Hatfield read the car for any residual error codes, but I will also have a look at the ABS connector for wear & tear & signs of age and corrosion.

If the X308 is as sensitive to volt drop as you suggest, a bit of contact cleaner and a tooth brush might be just as effective as a diagnostic reboot.

Thanks

Springelec

[Brakebuster]

i understand your skepticism ,
but its a known fact that the original battery wont last long past seven years or so, if its the original it will be 90% the cause of the problems

our cars ( i own a 1999 XJ8 to ) do not suffer from bad electrical connections, they are in the most-part bullet proof, the wiring does suffer in a few exact locations, such as the bootlid hinge point where it work-hardens from open/closing of the boot and breaks at this point, the headlight connectors also cook-off leaving them brittle, other than that i know of no other wiring faults other than the afore mentioned gearbox multiplug problem

they do however suffer from poor performing batteries causing ghost fault from door locks not working to engines not running and a lot of things in between including abs and restricted performance problems, this is well documented in all the forums and the majority of ' expensive looking ' faults can be rectified by a new battery

i would strongly recommend having the battery changed, leaving the car dead for ten mins to clear any codes, any codes that come back after a new battery as been fitted should then be accurate ones

and a new Jaguar battery is £80 . much cheaper than a gearbox , or even the diagnostics to find out its not the gearbox, if you see what i mean..

BB

i am currently under my car replacing the lower front ball joints and lower bushes , along with new anti-roll bar links

she has done 104k now

have you seen my ' tensioner replacement ' article...


BB

[BrianG]

Hi,

I am an electonics engineer and can confirm that, disappointingly, Jaguar electronics / software can do wierd things depending on battery condition. Last year I had a spate of "bulb failure" warnings every time I started the car. I'd jump out just to check if a rear bulb had failed, but no, both on fine. The bulb failure warning would only be reset by turning off the ignition and restarting. Cleaned bulb holders and connectors, changed bulbs - no improvement.....

Like yours the battery was the original factory fit. It was gradually getting slower as winter approached but still cranked at a fairly reasonable speed so that the car fired after about 1.5 seconds at the most. Bought a nice new 900A-capable HD battery from the main dealer and - hey presto - no more bulb failure problems. Boy does it crank fast!

[Brakebuster]

cool

i'm an electrical engineer , lol

BB

[joejag308]

Nice to have within a forum...........keep your hands in lads these 308s i think will give good cause for concern........Joe...