Ive just bought a '96 XJ6 X300 3.2 auto, which seems to be in petty good shape. It has a princes LPG kit fitted to it which seems to run slightly rough, having read through several sites i have a few things to try, the first being a new set of spark plugs. It seems the car is a bit fussy when it comes to plugs, with champion being the main recommended ones, but reading up o LPG the preferred is NGK. Does anyone here run LPG on these cars, if so what plugs do you recommend? Also should I be adjusting the gaps on the new plugs?

 

You may want to also post your enquiry on the UK/Eire forum as well as most members of this forum are from North America where very few X300s run on anything other than petrol.

 

There are 2 TSB's on the plugs for the inline 6 AJ16 as a reference point but does not specify the LPG operation so it is a reference point

http://www.jagrepair.com/images/TSB/...6%20Engine.pdf

http://www.jagrepair.com/images/TSB/...cification.pdf

 

I'd debug it first using petrol only.

That way you can follow the many posts about things like misfires, air leaks and so on and everyone will be familiar with what you should see.

 

Its much better on petrol, although I think there may still be a slight issue, it stalled a couple of times waiting at roundabouts first thing this morning, was fine when it warmed up. It struggled to get through the emissions test (not sure if they cheated and ran it on gas) think its running rich and it may be missing the Cats although I haven't had it on ramps to check.

 

Clearly faulty so go troubleshooting as the many posts on here detail.

 

I've managed to connect it to a Bluetooth obdII reader, it had no faults stored.
I checked both of the O2 sensors which I think are working correctly, go from 0 to 1.2 depending on what its doing, one seems to read 0 a bit more that the other?
I tried to read the maf but was only getting a reading of 0.1 constantly, I did remove the maf wiring which dropped the revs temporarily and then Idled OK, but revving it it was noticeably rough - think it is working correctly?
Is there any way of testing the coils or the crank shaft sensor?

 

Have a look at more posts, they can save you days and don't guess.

At the very least read up on fuel trims.

 

I found a good screen shot on the 'Little Help with my OBD' thread that I should be able to use as a base.
I have added the trim to what I watch, i can only watch short term trim on bank 1, can watch long term on both banks.
will try that after work