Annoying LX470 2004 mis on number 1 cylinder (2 Viewers)

[Elizaboy]

Background - 2004 LX470,duel fuel, 640,000 K's, new Iridium plugs, all coils tested & OK, 161PSI compression tested on all cylinders. Only repair was installing new valvs and stellite seats at around 250,000K's
Number 1 cylinder constant mis at idling on both LPG and Petrol, most noticible when in Drive, however when revs increase to 800-1000 smoothes out. No reduction in fuel comsumption and acceleration and speed seem to be unaffected.
Any ideas about what to check. Also a suggestion that there may be a vacume leak but with all the pipes and hoses, what do I check and where to start.
Appreciate any helpful ideas.

 

[excessive]

start by swapping coil packs, injectors, etc. around and see if the miss moves to a different cylinder.

 

[Elizaboy]

start by swapping coil packs, injectors, etc. around and see if the miss moves to a different cylinder.

Thanks for your reply, Unfortunately I have tried that with no effect. Cant be injectors as it misses on LPG as well as petrol. I am firming up on a vacume leak as mis is at idle and ok at all other times. Just where to start is my dilema.

 

[TahoeZ]

Have you tested compression?

 

[BoomerUZ]

What kind of diagnostic tools do you have access too? Usually when there is a misfire or condition that is hard to track I run the live data display and watch for the drops. What could be happening is sync loss, which is fairly common especially at higher miles. Where the wires cross over the front water bridge is a common failure point, but I would ohm out the CPS1/CPS2 and CRK