misfire one cylinder

[hitman2]

range rover 4.2 sc
palladio reducer
magic jet injectors
king ecu

misfire developed cylinder 2 only on lpg , no misfires counted when on petrol

have changed out injector , still the same

next checks chaps?

thinking try a new coil pack first? (they are on originals apart from one) had one fail about two years ago , plugs have about 50k miles on them

hoping the loom or ecu isnt giving issues as wouldnt know where to start tracking down a deterioration there , system has been installed since 2013 , new reducer installed two years ago and injectors have about 20k miles on them.

plan to purchase new coil pack and swith off cylinder 2 lpg injection as 2nd course of action as replacement spare injector had same misfires if not worse

any pointers from the pro's?

tia as always

[LPGC]

You know to swap the nozzle from the old injector onto the new..?

[hitman2]

No nozzles to worry about

Straight through, reducer 1.4b ish

Bloody cable not connecting to the ecu error c1 and it's pissing down, will have another bash when the rain drops off...

Main concern is no misfire on petrol, so worried if either loom or ecu is playing up...

[LPGC]

Pull the pipe from the injector on the cylinder with the misfire, see if gas 'pops' out of it when it's switched to LPG.

Like other injectors, one set of MJ injectors can flow differently to others, you need to make sure the set of injectors match in terms of flow, especially if running without nozzles.

Are they the full size/original MJ injectors or MJFX?

Is this one you converted yourself / did I convert it/ etc?

[hitman2]

thanks for the input Simon

before reading your post I managed to get the diagnosic cable working and disabled lpg to number 2 cylinder so thats on petrol only now , unfortunately cable has now totally given up the ghost and wont connect , dont know if its the cable or superseal connector to the ecu at fault , will order both and see what happens when rejigged

full size origianl magic jets btw

[LPGC]

If it won't connect turn the engine off, pull the fuse for the LPG system, disconnect the interface cable at both ends, close the software, then put the fuse back in, reconnect the cable, restart the engine, switch immediately to petrol and restart the software.

As I implied, MJ's from different batches can flow dissimilarly. It could be that the one you fitted flows so differently to the others that are fitted that you get incorrect mixture just on that one cylinder hence the misfire. Injector nozzles can help equalise the under-load flow if injectors flow dissimilarly but nozzles have less effect on very low load / idle mixture where it's more about the opening/closing speed of injectors than nozzle size. You could try fitting large nozzles on all injectors and re-calibrating.

Need to be sure you changed the correct injector though lol, iIrc that engine has odds and evens cylinder numbering so LPG channel numbers on your AEB based LPG install will be different to cylinder numbers.

[hitman2]

ahh too late

just ordered and paid for a new cable , pissing down again will have a bash tomorrow , did notice that when I disabled what I imagined would be cylinder two (bank 2 first injector )that a different cylinder stopped injection (bank 2 second injector) , went for what I would imagined should have been cylinder 4 (bank 2 second injector) and that actually related to cylinder 2 (bank 2 first injector) all from front of engine

banks are from front of car rhs 1357
lhs 2468

quick q should both banks have corresponding coloured wires working back from each bank

eg 1 and 2 same colour
3 and 4 same colour
5 and 6 same colour
7 and 8 same colour

cheers again

[LPGC]

I don't remember the Jag engine'd Rangerover petrol injector wiring colours. If petrol injector wiring colours are the same on both banks it would be intuitive to assume they run in the same order on bth banks but I know of a few engines on which they run in different orders per bank lol! When I convert some vehicles/engines I snip one petrol injector wire at a time, read the OBD error which tells me which cylinder number I've cut the wire for, then I know which LPG system wires to connect to the wire I snipped.

If you mean LPG wiring, yes on an AEB based system the colours should run front to back on both sides in the same order... blue, red, green, yellow front to rear. With petrol injector wiring in that order you should be able to connect plugs to LPG injectors in order ABCD front to rear on one bank and EFGH front to rear on the other bank. Some would argue that petrol injector cut loom wiring order doesn't matter much because the LPG ECU is fully sequential so follows the petrol injector firing order and strategy, so as long as you compensate for any deviation to conventional cut loom wiring by similarly changing the order of LPG injector plugs to LPG injectors it won't make any difference (except for maybe complicating diagnostics)... I say that although that is true of a lot of LPG ECU's, with an AEB ECU it does make a difference and they're not truly sequential, better to wire the cut loom and connect LPG injector plugs in the conventional order with AEB.

Just as an aside, with some ECUs you can assign which cylinder bank (bank1 or bank2) an LPG channel is on, so you could if you wished use channel numbers the same as cylinder numbers on an odds and evens cylinder numbered engine. The same ECU's might even allow individual channel fuelling compensation (tenths or hundredths of a millisecond to add on, plus a percentage to add/subtract, for individual injectors/cylinders) in addition to the same compensation for complete cylinder banks. But with AEB you only get the bank2 percentage correction, so even if engine cylinder numbers are odds and evens you're forced to wire them channel ABCD on one bank and EFGH on the other bank... You'd want to do that with AEB anyway even if you didn't want/need to use the bank trim feature.

[hitman2]

New diagnostic cable arrived in Lisbon today from somewhere in Poland, will update once I see what's what

[hitman2]

Miss fired on gas again, new coil pack fitted and all good

Received the cable from https://projekt-tech.com/ptftdi8-profes ... -p-11.html

This morning