I recently rebuilt my 4.0 v8 in my xk8 due to the secondary chain and tensioner failing. I thought maybe water in the gas was causing a rough idle but I drained some into a mason jar. It fires up but I'm getting a rough idle and codes p0351, p0354, and p0356. I've tried both swapping the coils and spark plugs from good cylinders to bad and I get no change in codes. I'm at a loss for why these cylinders are not getting spark. Any ideas on what to do to diagnose this issue?

 

go here and download the workshop manual for your MY, listed as the JTIS.

https://www.jaguarforums.com/forum/x...ts-data-29800/

In the JTIS under Powerttain - Engine - Engine Ignition there's a complete list of troubleshooting procedures for your issue.

 

What year and how many miles?

 

If its a 97 with an ECU part number ending in -AK then there is a good chance its the ECU doing it.


Dave

 

RJ, It is a 99 XK8 with 45k miles. Dave, I'm not positive the VIN but I will look into that. I'm guess that might be a common issue with the ECU?
Thank you Janreu, I'll have to get the JTIS all setup.

 

I don't think there have been many 98 ECU failures, but the misfire on both banks is a symptom often reported. The ECU number is on the VCATS tag near the spare tire.

 

Another symptom of a bad ECU that seems to happen with the 2 bank misfires is the CC not working. No red light when button is pushed.



Dave