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[JamesV6CDX]

I'm still trying to get the mapping right.

I'm having the problem that I can spend a few hours getting the lines on top of each other... but next day I'll watch the graphs again, and it will appear a mile off

These are the best maps I have come up with so far:







The last one looks like the best...I did this one this morning. It pulls by far the best using this map, with no missing at all, and deflection is less than 5%. But strangely, it is now stalling on gas when going back to idle from any speed.

Not sure if it's related to the map, because today is the coldest day I've driven it on since the conversion...

I'd appreciate any thoughts, I'm getting mildly fed up now, I want to stop tweaking and enjoying driving!

[JamesV6CDX]

If anyone has any ideas as to why it may be stalling using the last map, or any tweaks I could make to it, I'd appreciate very much.

I just wonder, if it's a case of the ECU needing to "learn" following the changes.

Obviously, caning the car and looking at the laptop is not a good idea (and probs not legal) - but I can see the lambda voltage at about 0.7 when giving some welly....

[Jay w]

i found that the LPG seems to be constantly learning, what we are creating is a base map with some fixed points from which it then adjusts according to conditions......

i spent most of Sunday mapping it again, got less than 5% deflection, both lines really close to each other, took it for a run of about 40 miles and there were no issues, next day 140 miles down the road i get the emissions light constantly coming on.....

since then i have not had it.

i agree with what you are saying about driving and using the lappy, not ideal

[cem_devecioglu]

Heres an idea ..

2 of you (who know the job) meet at one weekend..One drive, the other check the mapping ..

But as far as I understand ECU change the mapping according the conditions..Same in normal fuel..

Even the original ECU have problems with drastic temperature changes so the other (LPG) will also I think..

For controlling all factors you must know the correction algortihm inside the LPG ECU..

[Paul M]

Does it have a fuel cut-off on overrun function? Mine had the problem of stalling, mainly after stopping from speed, such as coming off the motorway with a roundabout at the end of the slip road. So I'd slow from 70 down to a standstill, dipping the clutch just before stopping. I suspect the problem is that the whole time I'm slowing, the throttle is shut and the fuel cut-off is active. Mine was set to do this at 1200 RPM and above, and I when the clutch was dipped the engine revs drop like a stone (due to no fuel). The system re-activates the fuelling at 1200 RPM, but with there being no gas between the injectors and intake valve it appears the short time before the engine RPM drops low enough to stall isn't enough for the fuelling to catch up. I could usually catch it with some heel-toe antics, but the pedal layout on the Omega is far from ideal for this and occasionally I'd get it wrong and stall it.

I adjusted it to 1800 RPM, and the problem appears to be gone. It's unlikely this is the same problem as yours, since mine is a much older system (installed in 2002) hence the reaction times are probably much worse. Certainly the mapping software is a lot less sophisticated than your system. But it's worth a look, should be easy enough to disable fuel cut-off temporarily to see if that's contributing to the problem. You lose a little fuel economy as the gas injectors are still putting in small amounts of fuel when the throttle is shut and the car is moving, but it's pretty minimal.

[Martin_1962]

Leave it now for a week, then have another go, the car needs to learn and the engine will be getting cleaned.

Also if you can turn off overrun cut off and try that

[Kevin Wood]

Overrun cutoff is a function of the main (petrol) ECU. It cuts fuel so the LPG system cuts fuel and unless possible with Tech 2 you can't turn it off.

When fiddling with James' install the overrun cutoff seemed to disengage well over idle speed after a blip. Probably at 1500 RPM or more so I doubt that's the issue.

It would be really nice to get some live data from the main ECU while mapping the LPG as that's the only way you'll get it spot on. If it's out, the petrol ECU will learn some new settings to put it back where it likes things, hence iot looks out again a few days later! Knowing what corrections the petrol ECU is applying is the key.

Kevin

[Paul M]

Overrun cutoff is a function of the main (petrol) ECU. It cuts fuel so the LPG system cuts fuel and unless possible with Tech 2 you can't turn it off.

When fiddling with James' install the overrun cutoff seemed to disengage well over idle speed after a blip. Probably at 1500 RPM or more so I doubt that's the issue.

It would be really nice to get some live data from the main ECU while mapping the LPG as that's the only way you'll get it spot on. If it's out, the petrol ECU will learn some new settings to put it back where it likes things, hence iot looks out again a few days later! Knowing what corrections the petrol ECU is applying is the key.

Kevin

Yes but with mine you can control the over-run independently, presumably it has a baseline minimum idle fuelling duration that it won't go under unless the revs are above the over-run threshold, regardless of what the petrol system is doing. I think the problem with mine is that the injectors are mounted on the sides of the plenum, so although the pipes supplying the fuel are right next to the injectors, there seems to be a small delay in the fuel being re-applied after cut-off. Therefore the threshold RPM needs to be higher than that for petrol to prevent stalling.

As previously mentioned, newer systems are probably more sophisticated and can react more quickly, so perhaps this is no longer an issue. Even the latest LPG systems are still a lot less sophisticated than any modern petrol system though, so they are continuing to improve all the time -- I'm sure you know this with your experience in mapping petrol systems.

[Kevin Wood]

Overrun cutoff is a function of the main (petrol) ECU. It cuts fuel so the LPG system cuts fuel and unless possible with Tech 2 you can't turn it off.

When fiddling with James' install the overrun cutoff seemed to disengage well over idle speed after a blip. Probably at 1500 RPM or more so I doubt that's the issue.

It would be really nice to get some live data from the main ECU while mapping the LPG as that's the only way you'll get it spot on. If it's out, the petrol ECU will learn some new settings to put it back where it likes things, hence iot looks out again a few days later! Knowing what corrections the petrol ECU is applying is the key.

Kevin

Yes but with mine you can control the over-run independently, presumably it has a baseline minimum idle fuelling duration that it won't go under unless the revs are above the over-run threshold, regardless of what the petrol system is doing. I think the problem with mine is that the injectors are mounted on the sides of the plenum, so although the pipes supplying the fuel are right next to the injectors, there seems to be a small delay in the fuel being re-applied after cut-off. Therefore the threshold RPM needs to be higher than that for petrol to prevent stalling.

Interesting. I don't think there's such an option with James' system. It certainly didn't seem to be causing problems when we mapped it, but with colder weather maybe so. I'd be surprised if the injector pipes made much difference. They can't fill with anything but vapour and the volume of vapour required to fire each cylinder once is probably well above that stored in the pipe, making the pipe length less relevant.

As previously mentioned, newer systems are probably more sophisticated and can react more quickly, so perhaps this is no longer an issue. Even the latest LPG systems are still a lot less sophisticated than any modern petrol system though, so they are continuing to improve all the time -- I'm sure you know this with your experience in mapping petrol systems.

This is true, but mainly due to the need to keep the petrol ECU in control of the engine. There are so many variants of engine control system, all doing other tasks such as controlling engine torque during automatic gearbox changes (sorry!), traction control, cruise, etc. that the gas system can't take total control over the fuelling. It acts as a mapping between injector times on petrol and injector times on LPG. Maybe that makes some functions, such as overrun cutoff, less optimal on LPG. The fact that your system has such a setting suggests it might.  :-/

Kevin

[Omegatoy]

hmm had similar problem on the last lpg motor i had, 3litre straight six dual ram, when i got the performance on a par with the petrol i had a constant problem with it stalling , couldnt tune it out but it turned out to be the lpg system is a lot slower to react then a petrol system i.e the vapouriser was supplying enough gas for highspeed then the throttle snapped shut and it had to clear the excess gas before it could tick over properly, does thAT MAKE SENSE?
ANY WAY THE CURE WAS WHEN SLOWING DOWN FROM A SPEED RUn,   to blip the throttle gently to help use the excess gas before coming to a halt, it soon beame second nature to do it and saved the constant hassle of stalling after high engine rpms
hope it helps
Omegato :yy

[JamesV6CDX]

Overrun cutoff is a function of the main (petrol) ECU. It cuts fuel so the LPG system cuts fuel and unless possible with Tech 2 you can't turn it off.

When fiddling with James' install the overrun cutoff seemed to disengage well over idle speed after a blip. Probably at 1500 RPM or more so I doubt that's the issue.

It would be really nice to get some live data from the main ECU while mapping the LPG as that's the only way you'll get it spot on. If it's out, the petrol ECU will learn some new settings to put it back where it likes things, hence iot looks out again a few days later! Knowing what corrections the petrol ECU is applying is the key.

Kevin

Do you think if I bought a "Device" over that's capable of reading the live ECU data, we would have a sporting chance at getting it spot on, then?

[cem_devecioglu]

backward engineering on embedded codes and algorithms ..

you must work in Bletchley park then  

[Kevin Wood]

Overrun cutoff is a function of the main (petrol) ECU. It cuts fuel so the LPG system cuts fuel and unless possible with Tech 2 you can't turn it off.

When fiddling with James' install the overrun cutoff seemed to disengage well over idle speed after a blip. Probably at 1500 RPM or more so I doubt that's the issue.

It would be really nice to get some live data from the main ECU while mapping the LPG as that's the only way you'll get it spot on. If it's out, the petrol ECU will learn some new settings to put it back where it likes things, hence iot looks out again a few days later! Knowing what corrections the petrol ECU is applying is the key.

Kevin

Do you think if I bought a "Device" over that's capable of reading the live ECU data, we would have a sporting chance at getting it spot on, then?

Sounds like an excellent idea

If that doesn't work, I have another idea. What do you reckon are the chances of being able to get one of your Lambda sensors out without knackering the thread? Time to try my Wideband lambda sensor?

I think some of the connectors are embedded in the Westfield's loom but I'm sure I could liberate them.

Kevin

[JamesV6CDX]

I shall get the plus gas out!

[Kevin Wood]

.. a plug from the end of an old Lambda sensor would be handy too

Kevin