Hi,

I've recently had an issue with a warm start-up misfire on my 2003 4.2 V8 NA S type.

Occasionally, it'll start from warm and run rough for about 20 seconds then settle fine and drive ok. Happened two or three times over a period of the last month with the last incident about a week ago which brought on the Engine Management light.

Put an OBDII scanner on yesterday which threw up the following codes:

P0301
P0303
P0305
P1313

I understand that the 1st three codes are showing the misfire on cylinders 1, 3 and 5 and that code P1313 is for Catalyst damage (I assume from unburnt fuel). Have cleared the codes and driven about 20 miles since clearing and no issues.

Am trying to work out what to do next - I can replace the coils on these 3 cylinders but wondered if there's something else common to these cylinders. I guess I could change coils around to see if the fault (when it happens again) but thought I'd ask if there was any other possibilities? Is it possible that all 3 coils have failed together? The plugs were changed at the last service some 2000 miles back....

One thing did spring to mind though - over here in the UK we're all drowning in heavy rain and I have previously had a problem with water getting into various bits of the engine bay. Also, I found yesterday that there is water getting into the boot by the battery and the terminals were wet - could this cause a misfire issue? I'm quite competent mechanically but am used to working on older XJ's and XJS's which don't seem to have quite so many electrical components!

Any suggestions really appreciated.

Many thanks

Mike

 

Hi Mike,

I've had a similar problem this week on my 2000 4.0.
Mine was missing and giving P0305 as the error. I changed the coil on cylinder 5 and all has been OK, so far. 80 miles have been covered.

One thing I was advised was to make sure that the wiring plugs on the back of the injectors were seated correctly, not damaged and free from moisture. Not sure if your later car suffers the same fate, but it might be worth a shot.

Good luck and keep us informed.

Thanks
Mike.

 

Hi,

Thanks for the quick reply. Will check for moisture etc as I suspect that as an issue rather than 3 coils going at once. I know it might be possible for all 3 to go together but previous issues with the car involved water ingress under the bonnet.

From memory, the problem has occurred when it's been raining or just after rainfall.... can't be 100% though. I just don't want to chuck endless money and head off in the wrong direction.

Thanks again

Mike

 

the is a good chance water is getting past the wiper cowl and dripping onto the plug/coil covers and contaminating the coils.