LPG Discussion Forum

Hi

I bought a is200 off a family friend who had it converted onto lpg in 2010 at 67k and now its sitting at 100k.

Car Is a lexus is200 auto 1999. The system fitted is a marini. All was well and ive had the car for 11 months, but few months back on lpg and when in Park and in neutral the revs would drop while stationary like a misfire, gradually moved to the drive gears also but once lpg switched off , the car would be fine on petrol?

Few weeks ago on petrol I had loss of power with the accelerator pressed half way down which triggered engine lights to come on the dash with codes for misfire on cylinder 1,2,4,6, I took it to the original guy who installed the system and he had it checked over and replaced the lpg gas pipes that go into the injectors and told me that was the issue and not the injectors as original thought by 2 other lpg specialist in my area. The misfire on the lpg went away on park, neutral and drive gears also.

car was fine for a few days before lights came back on the dash, with misfire on cylinder 2 with power loss on petrol again and also while running on lpg it had the same misfire issue, running slightly rough on lpg and I could smell gas in the car everytime I switched on the lpg.

I swapped the coil packs over from 1 to 2 and 2 to 1 and misfire disappeared and codes or engine lights never returned. Next day swapped the coil packs back to the original position, and the car runs fine right now on petrol. Point im making Is the car seems to be fine on petrol now have been driving it for past 5 days only on petrol and seems normal as everytime I switch it to gas I can smell gas in the car and runs rough on lpg including the misfire while stationary on park, neutral and now drive gears?

could it be something else like spark plugs, ive got ngk iridiums in had them in for 2 years so only covered around 20k miles but ive read lpg Is harder to ignite so if ignition system is 100% it will cause misfires.

im taking it back to the lpg specialist tomorrow but what do you guys think it can be in regards to the lpg issue, he said to me over the phone it could be injectors causing the rough running on lpg etc?

thanks guys and this is my first post on this forum so hello to everyone.

You are quite correct in thinking you need a good spark for LPG and the fact that by swapping the coil packs over you cured the misfire on petrol suggests a weak coil pack or iffy spark plug. Although NGK Iridium plugs should last for 40-50,000 miles, it might be worth treating it to a set of new ones to be sure. Rough running and a smell of gas does say something isn't right so hopefully your installer will be able to sort it.

Hey bud

got the phone call back from the lpg specialist, told me the gas leak was infact the car system running very rich for some reason? he has re calibrated it and he says its running fine at the moment with occasional missing in neutral and park but not turn off on lpg.

he also says the injectors aint the best as they are a little noisy but car still seems to be running fine on lpg.

he says to take it back and test it for a few days, if not then to get the injectors changed by him if any more problems occur?

is it worth bringing it back and checking if its running okay or shall I just call him and tell him to change injectors?

called me back and he told me took it for a drive, still has a misfire on petrol and lpg so could be coilpacks or spark plugs?

ive got 2 brand new coil packs which I can use on the previous cylinder codes, and I could change spark plugs,

but I would have thought him being a lpg installer could tell me which is misfiring, the plugs or the coil packs?

How much does he want to change the injectors? which type will he fit?

hey,

im not sure which injectors he is going to fit, but my injectors do sound noisy with a ticking sound,

he told me car is ready, went to collect and when switching over to gas, I smelt gas again in the car, luckily I was nearby so went back told him, he said It isn't gas lol, I said it sure is, he bought his metre out and confirmed it was gas and looks like its leaking near the engine wiring for lpg injectors?

his keeping it until tomorrow but the misfire lights came back on when I switched it to lpg, so misfire I think I need to sort out asap as soon as he fixes the gas leak tomorrow.

question is , why didn't he fix the gas leak when I told him and why did he say it isn't gas when it clearly was :s he is the original installer of the car but he seems like a cowboy?

Take it away from the cowboy and find someone else to fix it...
Huw

Lol , that's how I feel too but I cant find anyone else in Birmingham area who deals with marini systems.

anyway got the car back, leak has stopped, and no engine lights have come on so far in 7 miles. Its still has slight misfire in park and neutral but his told me that exists on petrol too and best bet is to change current denso iridiums to any standard spark plug with COpper core as they work better with lpg.

Ive also replaced the coil pack with a brand new one on cylinder 2 as that was the last cylinder to come up on the code reader before I took it to him.

is it true copper core plugs are better then iridiums for lpg? and his also taken out one of the injectors and said it looked fine so most likely injectors aint the issue.

I would have thought iridium tip sparks are far better.

I'm based in Birmingham and could take a look. I am still learning but they all appear to work on the same principle.

hey scotty, are you a lpg specialist?

also I think ive found the problem to my rough idle and stalling and maybe misfire,

ive noticed the throttle body is very noisy once car is warm, rattles quite a lot up and down .

Check the throttle butterfly doesn't have a blocked bypass hole or a build up of filth around the edge.
If it doesn't - check for play in the spindle -Throttle valves are useally expensive.

kbs wrote:Check the throttle butterfly doesn't have a blocked bypass hole or a build up of filth around the edge.
If it doesn't - check for play in the spindle -Throttle valves are useally expensive.

I checked the butterfly hole it self, its clean, but the noisy throttle body only starts making noise when switched to gas, on petrol the throttle body is quite?

got new set of iridium ngk plugs for my car, before I put them in I was wondering how do I adjust gap without damage the spark plug or the iridium element?

the lpg guy told me to adjust new spark plugs to 0.66ml so say around 0.7ml but these come standard as 1.1ml

You don't, leave them as they are. Seems your LPG guy knows a lot less than he makes out.

so is he talking @!## again lol,

and just to confirm ive had no more dtc codes on the obd2 reader, but on gas its still feels weird so will input the new sparks in today and wont adjust the gap on them , hopefully will fix the problem

changed the plugs to new iridiums without re gapping or anything, engine turned over fine and ran normal on petrol,

as soon as I switch to gas when engine fully warm it stalled, tried again stalled again, so tried again but never let go of the accelerator until few seconds after, then car ran very rough on idle, just seems to be jumping up and down on the revs, It feels like not enough gas getting into the engine and it wants to stall?

heres a video of the revs on lpg and then at 30 seconds I turned the lpg off see the difference on the needle.

http://vid1239.photobucket.com/albums/f ... G_8147.mp4

btw anyone local to me in Birmingham/Sandwell who can take a look at It?

anybody have marini software and cable around Birmingham? please inbox me asap

It needs tuning. Its not Idling correctly. Probably too lean...
If I change the mixture on mine (pulse width) incorrectly I can get it to basically hunt like video.

It may need tuning it may have a restriction somewhere that is making the mixture lean. Try contacting Tubbs, he may have the software and cable. He's not exactly Birmingham but he's Midlands ish.

Can you not just buy a cable and download the software. Then least you've got it for changing anything if you want to.

If you can find a cable. Marini is not a common one and none of the usual suspects list a cable.