lpg install woe..ideas?

gems 4.6..
sequential log kit, diy install..YES done loads before..(all worked perfect)
running batch fire..megasquirt engine ecu, map 2 controlling gas fueling via zavoli gas ecu..(gas ecu does feck all other than switch injectors, as megasquirt is doing the mapping..run the same on other 2 door rrc , its perfect)

it aint firing on number 4.(o/s bank number 2)
it is FINE on petrol..

so..i have swaped gas injector leads..stays same
i have swaped gas injector from good one..stays the same
so it aint the lpg injectors or lpg wiring..
besides i have unplugged injector pipe from manifold and you can feel,smell,hear the gas exiting the injector..

this leaves spark...but it is running boost..and has NO problems on petrol, which if spark was an issue i would have thought at 10psi it would show up! also spark on number 4 is excellent!ie hold plug over 1/4 inch from engine and it arcs across!!
it has brand new plugs..

unlikley to be a coil pack as would also miss on oposite plug (2 plugs 1 coil wasted spark setup)
so lead??but seems unlikey due to such a decent spark..

i will be swaping leads tomoz (not an easy job due to coil packs hidden behind supercharger)..but i do not think there will be a change, really i dont..

anyone can think of anything else it could be..remember its fine on boost on petrol..plugs are all the same colour on petrol,but on gas missing one is black in comparison.

gas injector nozzles are installed as close to valves as possible.gas nozzle of no 4 is clear and open (put pipe on it and blew down it..its clear..)

thoughts please..thanks..quite urgent as at 8-10mpg on petrol and since sally (the other one ) destroyed its gearbox no.7 (maybe clutch if i am lucky) on way to work this morning i need to use !

imo its a lead.might spark well but can throw a intermittent earthed 1 aswell resulting in guaranteed backfire on lpg

LPG ECU not opening Injector correctly? or No 4 Injection time out of whack with the others?

wil2813 said:

imo its a lead.might spark well but can throw a intermittent earthed 1 aswell resulting in guaranteed backfire on lpg

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this is what i am hoping..but that would just be too eay!!lol

and as for ecu not opening number 4 proper like..i have swapped injector leads, and injectors over (in the same bank, batch fire remember so dont matter which injector is connected as long in same bank)..no change..and ecu is a good un, was used on sally before i uprated to latest king ecu..so cant be that..would you not agree???

zen said:

this is what i am hoping..but that would just be too eay!!lol

and as for ecu not opening number 4 proper like..i have swapped injector leads, and injectors over (in the same bank, batch fire remember so dont matter which injector is connected as long in same bank)..no change..and ecu is a good un, was used on sally before i uprated to latest king ecu..so cant be that..would you not agree???

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well it happened to me on my d2 & boy was I lucky & happy drove mine back 150 miles on 7 cylinders with also a misfire making it 6 1/2 cylinders new plugs & leads now its like a swiss watch,now its gone dark pop the bonnet (no torche) run it up & look for duff leads arcing to earth

wil2813 said:

well it happened to me on my d2 & boy was I lucky & happy drove mine back 150 miles on 7 cylinders with also a misfire making it 6 1/2 cylinders new plugs & leads now its like a swiss watch,now its gone dark pop the bonnet (no torche) run it up & look for duff leads arcing to earth

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good point..ok lets annoy the neighbour time..

report back in a few mins..

so reporting back..you see i dont think its gonna be as simple as a lead..

no breakdown sparks..no belt as i hold lead and follow back to coil pack as best as i can, (cant reach behind blower(

must admit it sounds strange but petrol is more forgiving than lpg.your ignition has to be 110% for lpg but id still go for new leads as it wont hurt anyway, I gather you cant even see/feel them by the coil packs? could be slightly loose/split/burnt you never know until removed for inspection.

wil2813 said:

, I gather you cant even see/feel them by the coil packs? could be slightly loose/split/burnt you never know until removed for inspection.

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too right..gems 4.6 supercharged in a 2 door rrc..feck all room..

well bought a pair of bosch coil packs, mounted on inner wing, once i find some decent ht lead to make some new cables up will give them ago..
hopefully will do the trick..

Try closing the gap on the spark plugs as LPG needs a hotter spark not a larger one

Just an Idea but if your batch firing the injectors - can you easiliy move the suspect one to the other side and see if the problem moves? The it should be just a replacement? As long as the spuds and lpg lines are OK and not clogged?