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[Kevin Wood]

This must be a wiring issue. I'm damned if I can think how it's come about but, when running on petrol, the LPG system is just looping the injector signals through to the petrol injectors to which they were originally connected. Tapping into the RPM and 2 Lambda signals shouldn't be an issue.

I think if the checks we've already discussed don't bear fruit I'd be inclined to try disconnecting these 3 signals from the LPG system and removing the plenum and reconnecting the injector signals to the correct injectors. Let's try and get it back to running properly on petrol. If that's OK, something has gone wrong with fitting the LPG electrics.

What are the specific cam and knock sensor fault codes? Open / short circuit or incorrrect signals?

Don't discount the possibility, however remote, that the LPG system's loom is incorrectly made up :-/

It worked with no problem with James' car but they are presumably hand made and the possibility of error exists. Then again, as I say, I can't see how it would generate these errors unless something's gone wrong with the connections to the petrol ECU. Is it worth buzzing these through with a multimeter to be absolutely certain they go to the correct pins?

Don't give up on it at this stage. I think you're very close and I'm sure James will confirm that the system seems to work very well when it's behaving.

I'm sure we can work out a way to help if you don't manage to resolve it.

Kevin

[Jay w]

well some progress today...but still not complete  

we have got the car going, however i have destroyed a cat (it is rattling its nuts off, i damaged it driving home last friday  )
most of the fault codes have disappeared, we had a short that was causing two of the faults, but i have a knock sensor fault code that will reappear within minutes of it being cleared, on idle it will not reappear, as soon as we get above 1500 rpm it will flash up.

On petrol the car runs fune (aside from the knock sensor) on gas it has a bad misfire, we have put new plugs and leads on today, the dispack was replaced 10k ago, once we have it up to speed it will run, but not accelerate very will without missing.

Kevin, i have tried to use James's map, it will not allow me to import a map   and i will be the first to admit i find the instructions on how to map the system a bit unclear, but even if we had a good map i still feel it will misfire as you try to pull away and accellerate

One for the LPG experts, would a bad knock sensor give all the symptons of a plug lead that was going/gone bad (low speed and under load misfire)

[JamesV6CDX]

I'll confirm the system works well when I get rid of my missfire

Although generally it's acceptable on gas, accelleration is not the same as that of petrol, it feels a little asthmatic when given some welly. Saying that, I left a golf in my dust this evening when on gas, so it's not as bad as I make out - just .. noticable. Although, I guess there will always be a bit of a drop on LPG.

I also get a bit of hesitation when revved from standing start, but I think that's another characteristic of LPG, it's not noticable under normal driving.

I rekon I also need some new leads, and maybe a new coil pack to cope with the LPG - so we'll see what happens when I've investigated these options.

[JamesV6CDX]

I must say, I am a little concerned that we are both getting an "under load missfire".... using the same kit.

I do hope it's not a compatibility problem!

[Jay w]

mine is currently no where near as good as you, it is very gutless and feels like something is being retarded, i have to pull away on petrol and flick it over to gas once we have it up about idle........

[Kevin Wood]

mine is currently no where near as good as you, it is very gutless and feels like something is being retarded, i have to pull away on petrol and flick it over to gas once we have it up about idle........

Have you done any manual tuning? I had to add a lot of fuel to James' one further up the range. Can't remember if we tried to drive it immediately on LPG after the auto calibration but that procedure only really sorts out the fuelling close to idle. Shame that damn file didn't load.

One thought: I was using the latest version of their software downloaded from www.ac.com.pl IIRC. Maybe worth installing that software in case the file format has changed and we have incompatible versions of software?

I do hope it's not a compatibility problem!

It's hard to see what could be incompatible :-/ It only requires the injector drive signals and the RPM signal to run and these are working as evidenced by the injector durations and RPM in the live readouts.

It feels like an ignition misfire too. Maybe the output of the coil packs is a bit marginal for LPG. Have you tried closing the gaps on the plugs slightly?

Kevin

[Jay w]

mine is currently no where near as good as you, it is very gutless and feels like something is being retarded, i have to pull away on petrol and flick it over to gas once we have it up about idle........

Have you done any manual tuning? I had to add a lot of fuel to James' one further up the range. Can't remember if we tried to drive it immediately on LPG after the auto calibration but that procedure only really sorts out the fuelling close to idle. Shame that damn file didn't load.

One thought: I was using the latest version of their software downloaded from www.ac.com.pl IIRC. Maybe worth installing that software in case the file format has changed and we have incompatible versions of software?

I do hope it's not a compatibility problem!

It's hard to see what could be incompatible :-/ It only requires the injector drive signals and the RPM signal to run and these are working as evidenced by the injector durations and RPM in the live readouts.

It feels like an ignition misfire too. Maybe the output of the coil packs is a bit marginal for LPG. Have you tried closing the gaps on the plugs slightly?

Kevin

once we did the auto calibration i then took the car out of the road and did a lot of tuning, my biggest problem there was i am not 100% confident with what i was doing......

the car runs, but misses on idle, it sounds like it is running on 4 or 5, once it is up and running it smooths out, its behaviour is typical of an elecrical misfire, but the difference is soooooo great it is like driving two different cars, it is not a marginal difference, and seeing as the dispack was replaced not that long ago we are running out of ideas

the plugs were gapped up for petrol, would LPG need that much of a different gap?

[JamesV6CDX]

mine is currently no where near as good as you, it is very gutless and feels like something is being retarded, i have to pull away on petrol and flick it over to gas once we have it up about idle........

 

Oh no, it's not that bad. I don't see any noticable difference between the two, unless I am really giving it some large...

Sorry to ask again rather than read back - did you drill those injector nozzles?

I am still willing to bet that this is something really silly, like two transposed injector plugs...

[Jay w]

mine is currently no where near as good as you, it is very gutless and feels like something is being retarded, i have to pull away on petrol and flick it over to gas once we have it up about idle........

 

Oh no, it's not that bad. I don't see any noticable difference between the two, unless I am really giving it some large...

Sorry to ask again rather than read back - did you drill those injector nozzles?

I am still willing to bet that this is something really silly, like two transposed injector plugs...

yes, the injectors have been drilled out, the inkector wiring has been double checked today..

i am still getting the knock sensor fault code that will not go away so that will be changed tomorrow, i am hoping that will have some difference

[JamesV6CDX]

I've seen knock sensor wires cut clean off before, or unplugged, but it won't result in a missfire, unless your petrol is awful....

[Jay w]

I've seen knock sensor wires cut clean off before, or unplugged, but it won't result in a missfire, unless your petrol is awful....

no, on petrol it is ok, you know it is on a limp mode though, it is a bit flat but no misfire.......

misfire only on gas

[JamesV6CDX]

misfire only on gas

Same here - only not nearly as severe as yours.

And if it's not  HT related, I'm going to be stuck!

Only think I can think of, is the nozzles may need angling better? I might talk to sassanch, 'cos we couldn't realistically get the nozzles next to the petrol injectors..

[Martin_1962]

misfire only on gas

Same here - only not nearly as severe as yours.

And if it's not  HT related, I'm going to be stuck!

Only think I can think of, is the nozzles may need angling better? I might talk to sassanch, 'cos we couldn't realistically get the nozzles next to the petrol injectors..

Perhaps the Romano through plenum nozzles do work then?

[Kevin Wood]

Only think I can think of, is the nozzles may need angling better? I might talk to sassanch, 'cos we couldn't realistically get the nozzles next to the petrol injectors..

This is a good point. Injector angle isn't ideal going through the walls of the manifold. I guess at certain RPM there could be a bit of reversion in the intake that's blowing the gas back up the intake tract :-/

It sounds like you've got 2 different types of misfire though. James' car idled smoothly and misfired only under load.

Would be worth finding out what sassanach did. I have a feeling he posted some pictures on here.

Perhaps the Romano through plenum nozzles do work then?

They certainly allow you to get a better angle. However, I've been looking at a lot of conversions on the web and many of them have pretty haphazard nozzle placement.  :-/

What plugs do you use, Martin? Just standard VX 2 electrodes?

Kevin

[Martin_1962]

NGK 2 electrode as suggested for the 2.5 3.0 as 2 electrode is supposed to be better for gas