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**TheIronDuke** · 10-02-2010, 19:38

I've got a 4 ltr V8 that runs only on LPG, no petrol.

Its running rich, which means it stalls when cold, cos the gas running into the regulators stays liquid, when its freezing. Once warm water pumps round the regulators, she starts and runs like a proper motor.

The supposed 'gas expert' says he cant adjust the trims because you need to set it up on petrol, on the computer, then the computer automatically sets the trims.

I think he is full of shite. And is a computer geek, not a mechanic.

You must be able to set the trims, regardless of the fuel?

Any advice welcome.

**spannermonkey** · 10-02-2010, 19:50

Stupid question; is the fuel pump on the petrol side kicking in?

I've got a little experience of LPG and most of it seems to come from poorly set up gas/ air maps

**TheIronDuke** · 10-02-2010, 20:03

Originally Posted by spannermonkey

Stupid question; is the fuel pump on the petrol side kicking in?

I've got a little experience of LPG and most of it seems to come from poorly set up gas/ air maps

Theres no petrol. The petrol tank has been replaced by a second LPG tank. In addition to the one in the spare wheel hole.

Theres no fuel pump, because theres no petrol tank.

**jagman** · 10-02-2010, 21:05

What make of system is fitted?
I haven't done any for a while but all the parameters should be adjustable with the appropriate software.
Is your "expert" a fitter for the system you have fitted?

In simple terms, if your XJ8 is running rich you should theoretically be able to adjust that by on the settings the LPG ECU takes from the lambda sensor. On most systems the LPG ECU reads the exhaust gases and adjusts accordingly (its not quite that simple because the exhaust gases are different on LPG from petrol but thats the gist of it)
The LPG ECU sets the fuel ratio according to measured exhaust gases and not by directly mimicing the petrol injection.

As I said, I let my certification lapse some years ago and without system details and instalation date its hard to be precise. A big drawback to LPG conversions are the amount of muppets doing them....

**jagman** · 10-02-2010, 21:09

Just to add (a little bit of second guessing here) that the LPG system should not freeze up even when the vehicle is cold. The presence of coolant in the system should prevent that long enough for the coolant to warm up properly.
A possible cause of this is a mis-reading temperature sender, it used to be a common problem on Jaguar injection systems. The temperature gauge will function normally as the injection system and guage senders are generally seperate.
Without looking and knowing which system you have it is a guess but it could cause the syptoms you describe

**shark3432** · 10-02-2010, 21:57

Go on lpg website mate.

**ArmySurplusSpecial** · 10-02-2010, 22:16

where are you Duke? my mate runs an LPG installation company and is actually making his own systems now identical to a PRINS system. He is ex squaddie and well clued up on LPG.

He will have your answer

**TheIronDuke** · 11-02-2010, 22:14

Originally Posted by jagman

A big drawback to LPG conversions are the amount of muppets doing them....

Aint that the truth. In frustration I took it to the guy who does me Landy. Ex Landy main dealer foreman and works on all sorts from Quads to comfy cars.

"Sort this. Its an LPG problem"

"Nah, cant touch it. That would be illegal. You have to go on a 2 day gas course. Otherwise its illegal"

"Fuck off. Illegal is a big huge bird what lives in Scotland and America. It soars on the wind and eats fish. I seen it in a documentary on BBC2. This is a V8 Jag with a bolloxed LPG system. Sort it"

"All right"

Originally Posted by ArmySurplusSpecial

where are you Duke?

Newcastle, thanks for the offer.

The problem seems to be, it needs to go on the computer diagnostic. And since its all gas, it cant.

**TheIronDuke** · 11-02-2010, 22:23

Originally Posted by jagman

As I said, I let my certification lapse some years ago and without system details and instalation date its hard to be precise....

Its a Bigas tripoint, fitted about 9 years or 160k miles ago. So its had a paper round.

When its proper freezing, like it has been, it starts, then you have to sit with it at 2k revs with the thing sounding lumpy till the temp needle just moves. Then its OK.

Another thing its started doing... when you floor it to pass a truck, it loses power. Take the power up smoothly, and its OK.

I should have bought a Prius. You might not be able to stop them. But at least they go. I could get used to driving a hair-dryer. I'm sure I could.

**jagman** · 11-02-2010, 22:44

www.tinleytech.co.uk are a Bigas distributor and would be able to sort the problem but they are in Cambridgeshire.
They will also be able to supply software and a dongle to connect the system up to a PC to sort it out.
If I remember rightly Bigas systems can be set up to mimic the petrol injection system or manually programmed. It sounds like your expert doesn't know how to do it manually.

The symptom you describe of losing power on sharp throttle movements often relates to an intake leak on the induction system, causing the system to run lean (which would also apply to the cold running problem)

It once took me two days to trace a similar problem on a V12 XJS. Obviously these are just guess's from your description but unless you have has a flat battery lately (causing the LPG ECU to drop its programing) then the chances are that the fault is caused by something other than the LPG system itself.
A modern petrol injection system uses all its sensors and adapts fuelling to suit, the LGP system isn't quite as adaptable.

**jagman** · 11-02-2010, 22:45

Originally Posted by TheIronDuke

I should have bought a Prius. You might not be able to stop them. But at least they go. I could get used to driving a hair-dryer. I'm sure I could.

Don't be foolish! :D

**TheIronDuke** · 12-02-2010, 20:01

Originally Posted by jagman

Originally Posted by TheIronDuke

I should have bought a Prius. You might not be able to stop them. But at least they go. I could get used to driving a hair-dryer. I'm sure I could.

Don't be foolish! :D

I'd love to stay and chat, but I cant stop. I'm driving my Prius.

Fnar.

Thanks for the advice. I'll give it to me Landy man tomorrow. Jesus. Anybody miss the days when a half inch spanner, a hammer and a screwdriver would sort most things? Up to and including a Bolshy bird.

**jagman** · 17-02-2010, 10:54

Any progress on this one Iron Duke?

**TheIronDuke** · 17-02-2010, 17:37

Originally Posted by jagman

Any progress on this one Iron Duke?

Yeah, thanks for asking.

The Barge is with a proper mechanic and his monkey chums. I'm not ringing them every day to ask when I can have my car back.

They will ring me. Then I will pay them. Then I will plaster their name all over the internet, yea and verily, like Haleys fucking comet.

I'll do this not because I love them. I dont. They dress badly and stink of diesel. And Little Woppa stinks of ferrets. I dont ask, you know?

I'll do it because they are not computer plugging readout fairies, but proper mechanics. And thats a rare thing in the modern world.

I'll keep you posted.