Hi
Ive got a very annoying misfire that I can't fathom. Rough idle and splutters when accelerating. As I run lpg which is a totally seperate system don't think the problem is fuel related. Brought one of those cheap obd2 units off ebay and getting code P1138 02 sensor high. Have checked for air and vacuum leaks non apparent. Also have aquired an oscilloscope and checked the current to the primary winding of all six coils. All of these seem ok (followed the link from Jim Butterworths page) In any case they are all the same. I have also followed the advice on this post "failed emissions 1995 xjr code p1138"

 

An idea as requested.

Basic testing may find it.

Remove the coil pack plastic cover, find a DARK corner, and run the engine. If the coils are firing the scope will detect that they are firing, BUT, they may be firing to anywhere but down the hole, and the dark corner will show a fireworks type display very easily.

I was amazed, years ago, when I did that with the V12, fair dinkum, lights everywhere but where they were wanted.

The coils are becoming a common issue as age creeps in on this engine now.

Failing that I would head for the TPS, it may full of oily muck that has run down the throttle spindle, also getting quite common.

 

Thanks for that tried looking at the coils in the dark but all seems ok. I've only just done the TPS so know its not that. Decided to try a new temp sender (£10 from ebay) fitted it today and the car is transformed. Lots better still seems a little rough but might just be my imagination will let you know when I have given the car a good long run to clear it out. Also I will take it for retest and see what emmisions are like before deciding if its cured.

 

Sorry just read my original post. The post I was refering to should of been this one "97 XJ6 L rough idle and shake on acceleration"