win aldl

You have to be REALLY carefull when you start tring to right to Eprom in those style ECM's. You can wind up with a dead ECM. Did they no supply a updated EPROM for ECM ( then plug in that year) with conversion???

----------------- TheSnoMan.com

Thanks for the advice snoman, I will look into it. cheers xxxxxl

Isn't 1988 a little early for EEPROM? I think its just an EPROM in those ECU's.

Cheers

You are correct.

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Thanks all for the help, is there any setting i can change or am I stuck with the proglem? xxxxxl

Well for starters try advancing the base line referance timing. LPG has a really high octane (over 100) and burns a bit slower too. Stock timing is TDC, try about 8 or 10 BTDC and this should improve CO numbers (more burn time) and overall performance too.

----------------- TheSnoMan.com

currently running 18 degrees, and she goes very well, and good economy too.

Good, I am glad to see you are on top of this. How many KM per liter or gallon are you getting?

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The truck only runs on lpg, the original tbi is all gone except the ecu still operates timing and idle air control valve, in the uk a gallon of petrol costs £4.30 for £4.30 of lpg I regularly get 18 miles, and i did a long trip yesterday and she did 26, pretty good for a 454 bbc. the lpg mixture is adjusted by its own ecu, but i do have this problem with the engine light , its always setting a code for lean mixture. it must be that back in 88 less then 2.o co2 was considered lean , in uk

cars now run at o.o1 at idle.

I am curious, have to tested CO at idle with different timing settings?

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the co2 at 4,6,8,10 was all higher co but the truck didnt drive well, over 10 it improves very noticeably 18 is perfect but 20 is to much. I use a portable bluepoint tester, its accurate as i have matched it to a uk mot standard machine.

This is curious.... Kinda acts like it is over rich.

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allways sets code 44, but drives very well, no pinking or hesitatiion.

Given propanes octane I think it would never ping anyway with stock compression. High CO generally means either not enough burn time or no enough oxygen in mixture for the amount of fuel being burned. Also I have heard that LPG oversea where you are is actually up to 35% or more butane and not pure propane. In the states here propane is generally 90% or better pure. I wonder if the presence of Butane is messing up calibration because Butane has a much higher boiling point (about minus .5 C vs minus 42 C for propane) and it is possible that the butane is not vaporizing properly and burning late and causing higher CO. A possibilty anyway. (how are HC emissions?)

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Hi snowman and thanks for your time, interestingly the last m.o.t test showed hydro carbs as 1196 ppm, and the test limit is 1200, however the engine does use oil, but its only via the valve stem seals, do you know where i could get the tool to do the seals without taking the heads off?

Valve seals are pretty easy to do with head on. You need a adaptor plug to screw into spark plug hole and then hook it to a air compressor and give it the equivelant of about 120 PSI or so. THis will keep valves firmly in seat when you remove rocker arms and use a valve spring compressor tool to remove keepers and springs. BTW, you want to rotate engine to about TDC for the cyclinder in question/your doing to unload liters before you remove them. Also this places cam at proper agle to set lash which should be zero plus 1/2 to 3/4 turn.

If you can you might try turning down regulator pressure for LPG feed if it is a option. (just drop it maybe 3 to 5% and see what it does to HC and CO)

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thanks snowman i will try that.

Snoman made a small mistake. Do not put the cylinder at or near TDC, be sure it is at bottom because otherwise once pressure is applied the engine will turn.

If it is TDC or within a few degrees of it, it will not turn because it will not have enough mechanical advantage but none the less you bring up a very good point. BDC would be "safer", it is just that there either the intake or exhaust ramp on cam will still be active.

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