Outer Limits 4x4 Board

Okay I have Mazda e2000 dual cab ute which we have converted to a 3.8 v6 and the turbo 700 auto. The truck was mainly built to tow the buggy around and as my daily. We drove to Melbourne last weekend for the OZ ROCK finals.
On the trip down we were using close to 30 litres per Hundred km's on Gas. We had heaps of trouble with it backfiring on medium throttle climbing the hills. We checked and made sure we had no air leaks.
We ran it on petrol on the way home and got around 15 ltr per hundred.
I know gas is less economical than petrol but that seams a bit too much.
Any one have any ideas??

SAM

Sounds like the regulator thingumy is shagged (something is anyway). If you're getting 15 on petrol, you shouldn't be using more than 20 on gas.

When is the last time you had it properly serviced.

What type of system? Impco?

Just 1 single small backfire can put it out of tune. A back fire valve can be placed in-line. The mixer must be as close to the intake manifold as possible.

It's possible the diaphragm in the mixer, if it has one is damaged or way out of tune. When a backfire occurs, there is big flat washer that bends out of shape or the diaphragm itself, splits.

Also the V6 can have an electrical issue in the plug pins on the DIM, under the coil packs. I had this with mine for years and didn't know that was the problem, until I spoke to a Holden electrical guy.

It's an easy fix. Remove the 3 coil packs, undo the Dim plug, unbolt the DIM from underneath, (3 nuts, so unnut it) remove and scrape all the pins on the DIM module loom interface unlit they are shiny on both sides. This has fixed my backfire problem.

Also the coil packs themselves could be failing as well. Get a multi meter and measure the resistance across the lead pins on each one and compare it to a known good one. If the resistance is too high, get a new one/s.

Plug leads must be perfect too with little resistance.

The spark plugs should be NGK - 1 heat range cooler than normal and I think the gap must be closed a bit to 0.6mm, I think.

When I got LPG fitted to my Landcruiser it was using 45+l/100kms. It ran OK but not great. The problem got fixed by fitting a balance pipe somewhere. Now it gets about 30l/100km around town and about 24l/100km on a trip and runs great.

Emo wrote:The problem got fixed by fitting a balance pipe somewhere.

The balancing pipe, is for air pressure balancing when you have a snorkel fitted.

It is placed between the air filter box and the back of your LPG converter.

A snorkel does funny things to air pressure where it is fumigated with the gas vapor. This balance pipe simply applies the same effect of pressure differential to the lpg side of the converter help the Gas processor deal with the differential and supply the correct amount of fuel for the prevailing intake air supply.

[quote="v6hilux"]When is the last time you had it properly serviced.

What type of system? Impco?

It runs an OMV convertor and the mixer is mounted directly to the throttle body it doesn't have a diaphram its more like a venturi it has no adj or anything. The convertor has an Idle adj and a sensitivity adj. All parts are brand new( convertor is a month old and the mixer is less than a week old.

I will check the coil connections as we were getting a light miss on petrol as well.

SAM

v6hilux wrote:

Emo wrote:The problem got fixed by fitting a balance pipe somewhere.

The balancing pipe, is for air pressure balancing when you have a snorkel fitted.

It is placed between the air filter box and the back of your LPG converter.

A snorkel does funny things to air pressure where it is fumigated with the gas vapor. This balance pipe simply applies the same effect of pressure differential to the lpg side of the converter help the Gas processor deal with the differential and supply the correct amount of fuel for the prevailing intake air supply.

I don't have a snorkel. I took it to a place in Dandenong for a 4 wheel dyno tune and they sorted it out.

im sure ur diff whine would be loud enough to drown out any little popping noises

running lean or coils

OVERKILL ENG wrote:It runs an OMV convertor and the mixer is mounted directly to the throttle body

You have an OMVL converter with a fumigation ring. (positive pressure with a stepper valve)

Your problem is probably ignition electrical or engine timing.

Thanks will check all the ignition bits out today.

SAM