hi,

i have a 95 ef with a 96 xr6 motor 5 speed manual, has recently been put on an impco LPG system duel fuel

now, the guy told me to replace the spark plugs/leads and i have not done so (only got the system put in a week ago)

in first gear at low rpm (ie sometimes when you release the clutch without enough accerlerator and it bogs down at 800 rpm or so) it backfires occasionally. under those conditions is the only time it backfires. on petrol it runs fine all the time.

so naturally i rang up repco after plugs/leads and their bloke said that because it goes fine on petrol all the time it isn't a problem with the plugs/leads, rather it is the lpg system - mixer or converter. is this true?

i thought it could be the leads/plugs because lpg requires a better spark than petrol due to its octane rating. so naturally replacing the plugs/leads should cure my problem, and if not i should replace the coil pack, and if i still have a problem it lies in the lpg system. right? (i am no mechanic so a yes/no for my logic would be good)

second part, what plugs/leads should i get (yes i have searched but would rather provide my options as some brands are difficult to obtain)

1. ford plugs/leads: plugs 3.20 each but leads a whopping 150ish for all 6 (city ford)
2. ngk plugs - 5.20 for the lpg ones
3. champion leads - 50ish a set of 6
4. bosch leads - 60ish a set for normal, 80ish a set for performance

lpg guy said normally ngk is better but in ef/el the genuine ford articles are the best. i don't mind buying ford plugs but the leads price turns me off. i heared bosch are crap so is champion any good? any other alternatives in the price range? thats the on-shelf range at repco/supercheap

thanks in anticipation

I've got the same thing currently driving along normally then it starts to stall put your foot down a bit to get the rev's back up and sometimes she'll backfire, I don't think that this is a plug / lead issue because I've just replaced mine.

If its only been on for a week give it time because depending on the system you've gotten there maybe a LPG ECU, ie SprintGas system, also if your converters new it might take a while for the diaphram inside to loosen up and allow proper gas flow, give it a little while and see what happens and take it back after 1500k's and get a tune up done, having said that I didn't have a problem til I'd done about 500ks and even since the tune up its still doing it, going to take it to another guy and get him to look it over.

Might be worthwhile looking at your oxy sensor too while your at it.

Tell us what system you got put on might be helpful too

impco system just your regular one, full gear though not ahlf and half

i bought eagle leads and ngk lpg/xr6 plugs (supposedly the xr6 ones are more suitable for lpg) going in tomorrow

will see how it goes and let you know

don't know if its the ecu, i doubt it because there was nothing at all wrong with it when i was first driving it a few days, everything was going great. then backfires etc.. will be thoroughly p****d off if it still does it after new leads/plugs

with any LPG system, the ignition system needs to be perfect. Any problems will show up on LPG well before petrol. this includes, coil, leads, plugs, rotor, cap etc if applicable

I have the old right angle impco system on my EL XR6. My car if going up a hill would surge and shudder, kept getting worse. Got a new dizzy and ignition coil for unrelated reasons, and the problem stayed. Also had new Top Gun 8mm leads. I am running the NGK XR sparkplugs, which is usually the one gas cars run. I think they are one heat temp colder. BPR6 instead of BPR5?

Gapping the plugs down to 0.8mm made the problem much less noticeable. Eventually i got a set of Bosch 8mm leads, and the problem is now gone. I've always thought Bosch was a good brand, all depends on your experience with a company i suppose

yep i installed those ngk xr spark plugs, they are one temp colder. well no problem as of yet but its only been a day.

bought eagle LPG leads and they will go on tomorrow.. let you know if the combo is any good.

Apparently eagle leads are good but bocsh are sopposed to be really good but its so hard to tell???

i always though bosch were a bit bodgey.

the eagle leads look tops and say lpg on the rubber.. apparently they use them for the v8 supercars also, and they are nice and fresh having to be custom ordered in. 60 bux also. i'm happy with them. 8 mil lead is the one i got but they make them bigger, up to 11 or 12 i think

Keep the plug gap down to 1 mill/0.25 thou or slightly less to stop backfirng . I have fitted Eagle leads as well . but they are waste of money , good quality leads are all you need as well as standard plugs . Solved ALL my problems.

I have race series leads from IC & E, cost about $130 iirc, but they solved my issues, i was using champion leads before, which were only 2mths old & they broke down running on LPG. Had the IC & E leads on for a year now, no fuss at all. I also run at least a .1 reduction in the gap when i gap my plugs. Helps the spark jump when running lpg. Most lpg places i've ever spoken to about plugs usually advise reducing the gap .1 from factory gaps.

Cheers

ToranaGuy

thanks i've got eagle 8 mil leads and ngk xr/lpg plugs, no dramas any more

Just use dedicated LPG lead IE bosch or ring ICE ignitions and use NGK BP6EY-11 plugs.