LPG

[oze30]

http://cgi.ebay.co.uk/Sequential-Auto-G ... dZViewItem


This one

[gareth]

i agree, the price is offputting. once i've bought that, a lambda sensor, made up or bought an interface lead i doubt it'll be less than £200.

oh it's all soooooo confusing! i'd like to have a LPG level gauge, otherwise i'll just fill up every xxx miles on the trip counter. will these systems switch over to LPG once the engine is warmed up or do i have to do tha manually?

[gareth]

hi spadgeroo!

i plan to run a near empty petrol tank most of the time anyaway! i'm sure you'll agree that a bit more weight over the rear wheels on a 335i is never a bad thing either!!! the tank i have actually isn't that heavy. it's probably 15kg empty at a guess. an easy one handed lift into the boot.

looks like the LPG 335i touring will be the car of choice this summer!

[Brianmoooore]

oh it's all soooooo confusing! i'd like to have a LPG level gauge, otherwise i'll just fill up every xxx miles on the trip counter. will these systems switch over to LPG once the engine is warmed up or do i have to do tha manually?

LPG level gauges don't work very well - they are a rough guide at the very best. Trip meter is the way most people do it.
The normal way of setting up an automatic change over from petrol, is for the change over to occur on falling revs from the first time the engine reaches 2000 RPM, which tends to be the first time you lift off after you actually start driving rather than maneuvering.
Since you really only need to start on petrol when the engine is fully cold, I much prefer to have a simple manual change over.

[oze30]

tell me about it. That's why im trying to convert mine. Planning a european road trip this summer hols!

[Brianmoooore]

hi spadgeroo!

i plan to run a near empty petrol tank most of the time anyaway! i'm sure you'll agree that a bit more weight over the rear wheels on a 335i is never a bad thing either!!! the tank i have actually isn't that heavy. it's probably 15kg empty at a guess. an easy one handed lift into the boot.

looks like the LPG 335i touring will be the car of choice this summer!

Don't run it too low, or you'll damage the pump sucking air.

[oze30]

Gareth has it occured to you that by the time you have added all that weight to your car it will be no quicker than a 325

Cols car dropped about an inch on the rear when he chucked the tank in the boot

and thats empty!

Although, the tank is the bigger 65 ish litre jobbie and weighs about 40-50kg on its own!

But the LPG weighs less than petrol! A full petrol tank and a full LPG tank won't weigh a lot different from each other.

admittedly, yes, but the extra weight behind the rear axle will affect the handling a bit I'm thinking.

[Brianmoooore]

admittedly, yes, but the extra weight behind the rear axle will affect the handling a bit I'm thinking.

Slightly more polar moment, but I can't say I've ever noticed any difference.

[gareth]

this is a M30, i never go as high as 2000rpm!! i did once but that was at santa pod!

thinking about it, a manual switch can only be a good thing as i'm sure it'll help if things go wrong in one system or the other.
regarding setting the trip meter, i do it out of habit anyway to keep an eye on things.
on a car with a carb, i'd rather have a choke so i'm sure i can live with a lpg/petrol switch

[gareth]

hi spadgeroo!

i plan to run a near empty petrol tank most of the time anyaway! i'm sure you'll agree that a bit more weight over the rear wheels on a 335i is never a bad thing either!!! the tank i have actually isn't that heavy. it's probably 15kg empty at a guess. an easy one handed lift into the boot.

looks like the LPG 335i touring will be the car of choice this summer!

Don't run it too low, or you'll damage the pump sucking air.

good god, this thread moved on 4 posts each time i post one!!!

i pulled a noisy VW fuel pump apart a while ago to see if i cound repair it with bits of BMW ones. all bosch. did you know the fuel pumps through the centre of the motor and the brushes run in the fuel? not too bad til you run out of fuel and the brushes start arcing in fuel vapour!!!

when you're switched over to lpg, will the fuel pump keep things primed? i agree, if i ran out of fuel while on LPG, it could do nasty things to the pump!

[Brianmoooore]

There's no reason for the petrol pump to run at all when you're using LPG. I've been meaning to fit a spare rear window switch for about six years to switch it off.
Only time it needs to be switched on is for several seconds while you start a cold engine, and when you think you may be about to run dry of LPG and need to switch over. The first sign of running out of gas is the accelerator having no effect, usually when coming out of a sharp corner or a roundabout. Just goes flat for a second and refuses to pick up. This usually happens about six miles or so before you are right out.
Petrol pump needs to be back on before its needed to clear possible vapour locks out of the system.

[gareth]

ok, so i could have a switch for that too, next to the changeover switch. maybe a load of chrome toggle switches like battlestar gallactica fighters!!!!!

so when it runs low on lpg, it feels like running low on petrol on any other system. is carrying on when the risk of piston melting comes in?

[Brianmoooore]

so when it runs low on lpg, it feels like running low on petrol on any other system. is carrying on when the risk of piston melting comes in?

I'm talking about mixer LPG systems, not vapour injection systems - they all switch back to petrol when the pressure drops.
Doesn't run out like petrol does. When petrol runs dry, the engine dies. On gas it seems to run at the revs its already at, but just won't pick up.
Don't think you're likely to melt a piston, because it just won't rev. The Leonardo fault light will start flashing if you have the weak mixture option selected, but the biggest danger is from a blow back occurring in the inlet manifold. A decent blow back arrester should prevent serious damage, although the fourth (in six years), and last, blow back that I had earlier this year, actually blew a large chunk out of my air filter case.

[gareth]

i see, i think.

anyway, as my local LPG equiped filling station is 1 mile from home, hopefully i won't run out!

have you tried these:
http://www.autogasparts.co.uk/index.asp ... ductid=191
i assume it's like a section of perforated hipe with a rubber sleeve over it so if there is excessive manifold pressure, it blows it out. would that help? the M30 has a handy place for one of these to go, on the end of the manifold:


would a AFM saver be needed too or is it pointless when they're so cheap.
http://www.autogasparts.co.uk/index.asp ... ductid=191

[Brianmoooore]

You need a cat flap type blow back arrester fixed to the output flange of the AFM, which also has a relief valve built into it, and the M30 inlet manifold design just begs for a mushroom valve or two as well.
AFMs aren't cheap 200 miles from home at 2 a.m in the morning!

[gareth]

true!

[oze30]

So I am going to need the mushroom valve as well??

[Brianmoooore]

So I am going to need the mushroom valve as well??

Worth fitting if there's an obvious place to fit one like on the M30.

[oze30]

So I am going to need the mushroom valve as well??

Worth fitting if there's an obvious place to fit one like on the M30.

Does it have to be on the side? or can I mount it on th bottom somewhere? Looks abit cack having sticking out the side.

If I go full sequential, will I still need the cat flaps?

[Brianmoooore]

No cat flaps needed with injection systems, the manifold only contains air with these. With mixer systems you get a manifold completely full of propane and air mixed at just the right ratio to go bang, just as you do with carb. or single point injection petrol engines.
Only problem I can see with putting the mushroom valve underneath is that it'll get contaminated with oily stuff.

[oze30]

just went to the local LPG fitting place and said he wouldnt touch it as a single point is prone to back fire. i said i know.. but still wanted it done. He said no, and when asked about sequential, quoted me 750 quid, for the front end.

When I said Jeez!, he said you dont get something for nothing.

I hate people like that. No sh!t you dont get something for nothing, just I wasnt expecting THAT much to supply only!

Think I might go the KME or BiGas.

Anyone had any experience with kme??

[Brianmoooore]

just went to the local LPG fitting place and said he wouldnt touch it as a single point is prone to back fire. i said i know.. but still wanted it done. He said no, and when asked about sequential, quoted me 750 quid, for the front end.

When I said Jeez!, he said you dont get something for nothing.

I hate people like that. No sh!t you dont get something for nothing, just I wasnt expecting THAT much to supply only!

Think I might go the KME or BiGas.

Anyone had any experience with kme??

You're better off fitting it your self. That way you'll understand exactly how it all works, and how to keep it working. The installation can be done in easy stages, with no stage requiring the car to be off the road for more than a few hours.
Injection systems are wasted on a M20 or M30. Yes, a single point is susceptible to back fires, but apart from the odd heart attack amongst any pedestrians nearby, don't do any, or much, harm.
My car has had four back fires in the six years it's been on LPG. One was caused by me messing around under the bonnet with the engine running.
Another by me running on vapour trying to get to a filling station without reverting to petrol.
Another one was when my wife was driving. No idea on the cause of this one, but the relief valve didn't re seat itself afterwards and temporarily disabled the car.
Last, and most recent one, was provoked by a badly executed gearchange, and this one blew a piece out of the air filter box.

[gareth]

One was caused by me messing around under the bonnet with the engine running.

i bet that woke you up!!!!

[Brianmoooore]

One was caused by me messing around under the bonnet with the engine running.

i bet that woke you up!!!!

I didn't repeat it!

[oze30]

Hmm.. blowing airboxes ap[art. What happens if there's no airbox, but cone filter?

[gareth]

i guess it would look like a flower!!!

they're silly anyway, get the M30 airbox back on, it's got a massive filter, works very well and will house the LPG mixer with ease. as well as looking factory and having a cold air feed.

i bet your cone has 1/2 the filter area!

[oze30]

How do you mount it in the airbox? Pics?

(My airbox to afm hose has split something viscious! Need a new one. The filter is a nice itg jobbie, but I maybe needing it later on!

[Brianmoooore]

The mixer fits the four bolts that bolt the air filter box to the AFM. I removed the trumpet in the airbox and bolted the mixer to the AFM with longer bolts after first unscrewing the gas inlet stub pipe. I then drilled a hole in the side of the airbox that lined up with the threaded inlet port in the mixer and made up a stub pipe that screwer into the mixer, came out through the hole, then turned 90 degrees backwards.
This was all on a M20 installation, and the main reason for putting the mixer inside the airbox was to avoid moving the airbox any further forwards than the 30mm required to fit the blowback arrester.

[oze30]

hmm.. m30 would be interesting as those 4 bolts arent there. need to have a squiz inside my airbox i think.

[gareth]

as above, the M30 AFM is on top of the rocker cover. there is a handy plain straight hose between the AFM and TB though.

does the mixer have to be upstream or downstream of the AFM? eg, is there a significant amount of gas that needs measuring or is it negligable?

[Brianmoooore]

Short answer is that the mixer needs to be upstream of the AFM, as the closed flap seriously affects the pressure between the AFM and the throttle butterfly.
Longer answer is that you can use a pneumatic ram operated by gas pressure to push and hold open the AFM flap while running on LPG, or you can use a vapouriser where the 'atmospheric' side of the diaphragm is connected by a pipe to just downstream of the AFM, so that the vapouriser sees the reduced pressure rather than true atmospheric.
What ever system you choose, make sure that the idle control valve gets fed gas mixture and not just fresh air.

[oze30]

I dont think it would matter where it went into. Just easier to fir it where the afm inlet is as the bolts are already there. Going to have a play sometime on the weekend to see what I can fit and where.

Do you think it would be possible to remove 30mm from the afm/inlet hose to fit the cat flap? Or am I going to have to trim the little ribs off the hose to fit?

[StuBeeDoo]

just went to the local LPG fitting place and said he wouldnt touch it

I had similar problems when I was enquiring. Got various excuses not to supply single point, including one of "It's not legal anymore"! Cheapest quote I got was £1200 fitted for vapour injection, and one place quoted in excess of £2k.
Taking Brian's advice, I shopped 'round for a single point closed loop system and ended-up buying from Gordon Finlay.
I decided against buying second-hand as having a parts warranty appealed as did having a technical back-up (I don't like to keep bothering Brian).

[gareth]

time to drag this back from the depths i think! i've made some seriously slow progress!!!

i've now got the front end setup sorted (cheers oz!) and it comprises of the following:
- OMVL R90/e vaporiser (used)
- 2x lpg filter/solenoid valves (one new, one used)
- Leonardo ecu, stepper motor/valve, switch/gauge unit, labelled wiring loom (used)
- correctly sized mixer plate + combined catflap and pressure relief valve jobbie (used)
- Filler/pipework/mangled loom fragments! (used)
- Corectly sized donut tank with multivalve etc. multivalve has a 0-90 Ohm level gauge according to the markings. fresh rolls of plastic coated copper pipe (new - well ages ago when i bought it!!!)

initially, it looks like i need to source the following:
- oxygen sensor + stub to weld to exhaust
- laptop connection lead and software for the leonardo ecu
- random hoses, wiring, etc etc


will the 0-90 Ohm level sender work with the leonardo's gauge?
do i need an ignition fiddling module to adjust the timing?
what oxygen sensor can i swipe from the breakers?
does anyone have a wiring diagram for a leonardo ecu i can copy?

[Brianmoooore]

Got the software, two designs for the lead, and the Leo wiring diagram!
Send me a blank CD with a return envelope, and I'll run you off a copy.