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[rodstares]

Thanks LPGC, that's great info. I think I'll try shimming it first and if that's no good then try a double spring arrangement. What thickness shim do you reckon to try first? Very thin shim material or something like a bodywasher? Do you know how sensitive these are typically?

[LPGC]

Sorry I can't be of much help regards springs for this reducer.

In your position I'd try a shim first... Reducer pressure adjustment screws just move a base plate that the spring seats on and most have a range of movement of around 10mm... maybe try a 5mm shim? if it works, great, or it may give insight into what size shim to use.

If totally no joy I'd either give up and buy a different reducer or I'd refresh my memory on how to work out spring rates, check the spring you remove and try to get hold of a suitably uprated spring, might be off a shelf or might be made custom by a spring manufacturer if cheap enough. I've been doing a bit of research into custom springs lately (for something totally unrelated), seems there are a few manufactures.

Would be possible to calculate how much force the spring needs to have to get pressure output at your chosen level and the calculation could be confirmed by checking current pressure (0.9bar) against force of the spring at current pre-load.

[rodstares]

Awesome, I'll have a go with a suitably sized washer or two.

[rodstares]

Found the perfect size body washer so I can adjust in increments of 1.35mm, I'll put three in to start and see what I get. That spring is a lot more powerful than I was expecting.

[rodstares]

Well, a slight overshoot but definitely effective, warmed up the engine, switched to lpg and pressure went straight to 3.1 bar and the pressure release valve went off. I'll take a couple of washers out and try again. I used 4 washers, should have stuck with the 3...

[rodstares]

Alright, 2 washers is giving me 1.27 bar engine off and about 1.15 bar running at idle. Running better for sure. Petrol injector about 3.9 for gas injector 5.6

[rodstares]

This is going to work, just need to fine tune. 2 washers not enough, 3 washers too much. It gets up over 3 bar with 3 washers. At three bar the engine runs well, revving hard and idling smooth, until the prv blows. Anyway I am currently cutting shims out of beer cans to get the tension right. I can see the advantage of an adjustment screw...

[Brian_H]

3 bar will probably cause you issues with injectors opening anyway, sounds like your getting closer to what's needed now though.

[rodstares]

Got it at 2 bar when on petrol then dropping to 1.5 ish when running on gas, idling pretty nice. Can't get auto calibration to run, it says stabilize on idle and wait then doesn't do anything. Wait how long I wonder?

[rodstares]

Auto calibrating away now but I get ECU coms failure before it can finish. Frustrating. Software or ECU issue I wonder?

[rodstares]

Finally got it through auto calibration without a comms failure, running pretty nice now. A question, if the power is disconnected will it retain its current settings? You'd hope so

[rodstares]

Going for a road test, wish me luck

[rodstares]

Glad to report she's running like a beauty. Spot on for just ordinary driving about only one issue, it cuts off the gas, switches to petrol and sounds the alarm on the switch under heavy load. I'm talking 3 tons of Landcruiser pulling uphill with wide open throttle, she gets to about 3500 rpm and says no thanks, I need some petrol. Is that something that can be turned for or should I just set it to switch to petrol at 3500 rpm and be done with it? Apart from that little issue I am very very pleased. Only one problem, I just filled up the tank and gas here is 64 cents a litre while petrol is only 87 cents, not worth running gas just now. I am sure petrol will be up again in a while or gas will drop. Anyway, it's certainly been a good project and I can't thank you blokes enough for helping with all my dumb questions. I'm doing a 400 km trip on Friday so I'll have a good idea of mileage after that. Then I'll be away at work for a month so she'll be on hold till I get back.
Thanks and regards,
Rod

[rodstares]

Update, I set it to switch to petrol at 3500 rpm and it works like a charm, that'll do for now.
Cheers

[Gilbertd]

Nice one. I suspect it's switching back to petrol at 3,500rpm due to the limitations of the reducer so the pressure is dropping and it thinks you are running out of gas. A beefier reducer would cure that but as you say, that can wait for another day.

Similar situation in the UK with fuel prices. It was around £1.25 a litre for petrol and between 58p and 68p per litre for LPG. Now it's down to £1.05 for petrol but the price of LPG hasn't changed. They will probably argue that as LPG is a by-product of producing petrol, as there is less demand for petrol they are producing less so there is less LPG available.

[LPGC]

Great stuff!

Don't forget that if pressure is now 1.5 bar you should set reference pressure in software to 1.5 bar too and doing that will mean re-calibrating (probably worth resetting the ECU before and re-entering basic settings again before running autocal). But save settings before changing anything, so you can always get back to how it runs now.

When that's done, tell us the numbers in the far left column of the map... Autocal only really sets calibration properly for the rpm and engine load it sees during autocal which is fast idle no engine load, the rest of the map needs to be set manually (one of us will write an explanation on how to do that in another post).

As Gilbert says, your reducer may not be capable of converting enough liquid gas to vapour to supply the engine at combinations of high rpm and high load. But if the mixture (calibration) is set too rich on LPG at high rpm and high load the reducer has to convert more gas to vapour than it should be converting for the rpm and load, so if it's too rich it's more likely to reach the limits of the reducer.

It's possible to set the system to add some petrol to the mix above a certain rpm and engine load, obviously any portion of LPG substituted by petrol is less LPG that the reducer has to convert to vapour, so petrol addition can be used instead of a complete switch back to petrol. But first you have to set mixture correctly to find the true limits of the reducer, then you dial in the petrol addition.

As it is now how does gas injector duration (ginj) compare to petrol injector duration (pinj) when your're driving at moderate engine loads (say when pinj is 6 / 8 / 10) at around 2000rpm? Have you ever noticed the yellow LED on the switch blinking during driving?

[Brian_H]

You might also find the feed line isn't really upto supplying the required amount if its a 6mm one given you've gone from single point to sequential, I would assume you've kept the same feed pipe that was fitted before?

[rodstares]

I might get a chance to play about with it this evening otherwise that's it for the month, I'm off to work. Haven't seen the yellow led on the switch at all. The feed pipe is the original one from the old system and now that you mention it the one that came with this system was bigger.

[LPGC]

A 6mm feed is usually OK for 250hp even in Britain's climate (more tank pressure to push gas through narrower feeds in warmer weather)... unless the feed pipe is crimped enough anywhere enough to restrict flow.

If the switch flashed the yellow LED when you put your foot down it'd be because the ECU calculated that the gas injectors would need to be pulsed for longer than the available pulse duration window (pulse length window is rpm dependent - time between the inlet valve closing and opening again on a cylinder).

Look forward to hearing from you on your return from work mate.

[rodstares]

Cheers and thanks again. I'll be looking to get the tuning right as possible when I get back so expect some questions! Also, I never got a reply from Tinley about sourcing a temp sensor for this reducer. You wouldn't know where i could get a 10mm sensor would you?