Hi,

My 1996 Xk8 4.0 has just developed an intermittent fault:-
"Engine fault / Poor vehicle performance" with Fault codes P0352, P0353, P0355, P0358, P1336 & P1368.

The car runs fine from a cold start and this problem develops about 20-30 min into the journey, and goes away again when cold.
I have cleared the error codes (when hot) and the fault comes back, unless I hold the revs above 2500, then the fault stays away (re-appears as soon as I let the revs drop)

I have read all sorts of possible causes on the internet, from Gearbox oil, to plugs, crank sensor, MAF sensor, Temp sensor, ignition modules, jumped timing chains, etc.

I have swapped the ignition modules from side to side and the same cyl's pop up when the error re-occurs.

Have fitted new coolant sensor. Very puzzled. Any Ideas, Help!!!

Tony.

 

Unusual that it only occurs when hot, but still probably ECU needs rebuild. It often happens with early XK8's. I know there is a source in the UK as another member had the same problem recently and it was pointed out to him.

 

I just found the reference, it was for AJ Motorworks, on the sponsor list. But it appears they are not in business. I sent mine to ASI in Tennessee, link below in case you can't find one in UK. A used numbers matching module might work but would probably need dealer or other shop computer to set the other modules, and might also fail.

http://www.autoecu.com/

 

I used ASI for my ECM and other non jag stuff. they are good!

 

but yea I STRONGLY feel anyone with early models like yours through 1998 should make the ECM a maint item to have looked at. It is easy to take out, you will down for 2 to 4 weeks from time you mail it out till they get it back (in the states).
These things act up and cause so many FALSE issues via various multi check lights all at once, or out of no where and make the car seem that the sky is falling, get the lousy performace issues, warnings.

 

**** FIXED ****

Hi, Thanks to all, your replies were spot on, after further investigation on ECU/ECM issues on internet I found that this is indeed a common problem with this XK8 of this age and that the issue is due to old capacitors which leak and corrode circuits paths.







So I removed the ECU and opened it up and found exactly that. There are 7 electrolytic capacitors of which 4 were leaking.



Armed with a soldering iron, I removed the offending capacitors (including the one not leaking as a precaution) and replaced with new ones from Makro (£2.68 in total).
The capacitors were all located in places well away from sensitive IC chips, so little risk of overheating components with the soldering iron, Still I took my time, very carefully taking nearly 3 hours to change 7 capacitors, making sure I did not drop solder anywhere or overheat the board.
Seem to have caught it in time, very little damage to circuit paths, easy to clean.

Put it back in the car today and....... it worked, the fault has disappeared and he car is driving normally (seems smoother as well)
Only done about 20 miles, but the problem used to re-appear within 2-3 miles of clearing the codes - so I'm very hopeful that it's fixed permanently.

Again thanks for your advice - perfect!

Tony.

 

Well I'll be ... Nice work.

 

DIY - excellent!

 

Good stuff: well done.

TBH, 20 years is stretching it even for high quality automotive-type electrolytics, particularly in the hot environment of an engine bay.

 

RJ237
'I just found the reference, it was for AJ Motorworks, on the sponsor list. But it appears they are not in business'
What makes you think that they are not in business? The link on the page doesnt work (dont know why) but just google AJ Jaguar and the correct link is shown

 

tonyforman

Thank you for some excellent information. Should you by any chance have the numbers (values) of the capacitors needed?
Best rgs.
Oyster

 

Hi,

Yes, Capacitors specs are as follows:-
1 x 560uf, 50V, 105°C
2 x 47uf, 63V, 105°C
2 x 220uf 10V, 105°C
2 x 10uf, 50V, 105°C

By the way, still running without issue 2 weeks on and 300 miles.

Also noted that poor hot engine starting issue has gone away also.
Used to have to start using throttle when hot, (took some cranking)(fine when cold)
Now it starts when hot perfectly.

Tony.

 

Hello! I would like to know, when this problem occured, was the engine sputtering? And did it happenned mostly when the weather was hot outside (say above 25 degrees celcius) ??

Thanks