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[Kevin Wood]

One of these?

http://www.ac.com.pl/en/produkty/12/timing-advance-processors

Sort of, but that introduces another "piggy back" bodge, so I'm not keen on the idea.

[Omegatoy]

Maay be completely off the boil here,but having ran lpg on severall straight sixes for over ten years,
had very similar problems with long tickover periods resulting in over fuelling,then a small lag till the cylinders cleared themselves,and similarly a problem at wot for long periods,
eventually got it running much better,by putting some sensible numbers in the map,but it never completely cured it, however after much experimentation we turned down the vapouriser pressure , then again did the numbers,reduced pressure again, and agin put differect numbers in the map,anyway after a lot of time doing this reached the best compromise we could and the car ran cleanly,all the way through,
except!!!

over 5.5k on track we found gains to be had by switching back to petrol, as you said the car does not spend its life doing above this limit,so even tough i was screaming around silverstone/castle combe etc
car always switched to petrol above 5.5k, eventually i learned to drive up to 5.5 then change gear just before the switch over,and believe it or not didnt lose much over a lap on times,with a 80 litre tank
70 litre approx of usable gas,it would give me  around 26/27 mpg,admittedly my commute was from ardley to corby(69miles each way) everyday and back,but at normal speeds and the occasional blast to upset idiots in high power hot hatches,I was extremely pleased with it,did  129k in 3 years, now this was a romano system which had two rotary injection motors rather than injectors but im pretty sure the basics apply?
food for thought i hope!

edit,at the time I was paying 29.9 per litre form corby lpg centre it was 35ppl in garages!

[Kevin Wood]

Yep, there's a juggling act with LPG injectors that have such slow open/close times, IMHO. At idle they can easily over-fuel, and when the fuel trims try to cut back the fuelling below the open/close time, they stop opening at all, meaning the engine stumbles, the ECU goes back to fixed fuelling and the idle stabilises again, and so on. Conversely, at full chat, you may struggle to get it rich enough even with them full open.

[chrisgixer]

Yep, there's a juggling act with LPG injectors that have such slow open/close times, IMHO. At idle they can easily over-fuel, and when the fuel trims try to cut back the fuelling below the open/close time, they stop opening at all, meaning the engine stumbles, the ECU goes back to fixed fuelling and the idle stabilises again, and so on. Conversely, at full chat, you may struggle to get it rich enough even with them full open.

Current injectors being over rated for this engine, are too rich at the top end. The map is a totally different shape to the old moto gas injectors. Lower at tick over, which improved the tick over hunting, higher but not as high as the old injectors in the mid range, and lower again at the top end in attempt to back it off.

I need to set it to switch back to petrol at high rpm. But the mid range is noticeably cock on and strong at 10c outside temp, 4000rpm on 2/3rds throttle. It really doesn't need revving out at wot.

...which reminds me. It does seem to struggle (relatively speaking, generally speaking its fine ) with seasonal/general temp changes.

[TheBoy]

Have you looked at the 3d map, which takes engine load into account? Wondering if you can tune out the richness at high load/high rpm.

Where did you get your other injectors - I think I may be replacing my motogas ones soon

[chrisgixer]

The what?

Tilo got had them left over in stock. The mid range is fine, but like I say they are 80bhp to big. So at Wot, when the petrol injectors are giving max duration, so are these, and it floods it/goes rich very quickly.

See what your saying, but its mist obvious at high rpm.

Might play later.

[Kevin Wood]

Do we know it's rich at high RPM?

TBH, if the injectors are too large, it's normally at the idle end where things suffer, since they can't supply a small enough squirt of gas.

[chrisgixer]

Do we know it's rich at high RPM?

TBH, if the injectors are too large, it's normally at the idle end where things suffer, since they can't supply a small enough squirt of gas.

That was the consensus last time we mapped it. It was ALL rich prior to. You sorted it, but we decided to live with the top end.

Yes altough these are kehin(?) copies, made by Hanna. About £100iirc. No messing about with drilling nozzels. So do all the work on duration only. I presume that means better control ?