rough ground, idle surges

[Regulus]

Hi All, I have a 2000, 3ltr turbo diesel which has been converted to run on gas. The set up has been done by a company called E-gas in Perth, West Australia, and when the engine is warm, the system injects gas into the intake before the turbo. Makes a huge difference to power and efficiency.

 

That's not why I am here. You see, if I were to go over uneven ground and the car rolls from left to right a few times, not very heavily, after a few moments I get the engine warning light and the idle can jump from 700 up to 1200 sporadically. It'll do that and sometimes stall, for about 30 seconds and then it disappears. Are there issues like this recorded before or do you think it may be an issue with the gas?

Any help would be greatly appreciated.

Regards, Matt

[Slartibartfast]

First I've heard that you even could convert a diesel to gas. The rolling/idle is odd. First thing I'd do is check the wiring, make sure there isn't something that's swinging loose and stressing ground or sensor wires when the truck rocks.

 

Also, by gas I assume you mean gasoline and not LPG or something? LPG I can see being an issue if the tank sloshed and shot liquid instead of gas out the line, but I'm not sure what would cause a gasoline system to surge like that other than a bad sensor connection somewhere.

[Regulus]

Thanks Starti. Separately alongside the 60L Diesel tank there is a 17L LPG tank. When the engine is at temp, the gas gets injected at a fairly low percentage. Roughly 17L gas per 120L diesel. Its makes a fat load of difference. Apparently the gas is Hygroscopic (???) and causes the large carbon chain of the diesel to elongate (???) and burn more efficiently. The LPG does not truly fire, it merely opens up the diesel for a more efficient burn.

 

On topic, the wiring was checked to be in order but who really knows without fully checking every terminal! Also, the issue raises when either tank are at any level, full or low. Someone last night said maybe the fuel pump which has merit as usually the issue arises about 30 seconds after going over rough ground or fanging around car parks dodging old ladies.

[Towncivilian]

Hygroscopic means it absorbs moisture readily. Though if the gasoline has ethanol in it, this is less of a problem since ethanol "dries" the gas.

[Regulus]

L.P.G. is injected, not petroleum or gasoline liquid. Hygroscopic is not the correct term I was looking for, but the fitter said something like that.

[bushnut]

my idle does that too. but only on restart when the engine is warm. if I shut it down and run in to a store or something upon restart the idle jumps from 750 to 1200 and back but when I put it in gear it settles back to 750. I've alway thought it had something to do with the idle control sensor.

[fixinto]

may want to check for a vacuum leak, when you go over uneven ground maybe something flexes under there and causes a small gap to open, other than that, im with that other fellow about the loose sensor plug. =) Sorry i couldnt be of more help.

 

have a good day