Help with LPG conversion in progress

Post Tue Jan 24, 2006 7:34 pm

I've bought a single point, closed loop conversion kit last weekend and have started installing it.

I know there are a few on the zone (Brianmoooore etc...) who have done this and I was hoping to get a few pointers as I go along with this conversion.

I've got the tank and associated plumbing and electrics done last weekend so next I've got to tackle the stuff under the bonnet. The questions I've got at the moment are:

1) Lambda probe - My '88 325 never had one so I've got the boss to weld into the exhaust but I don't know how far 'downstream' from the manifold to do this. Will it be necessary to take the exhaust off to do this well, or will I be able to do it on the ramps?

2) Wiring for the probe. Can I obtain the loom the later cars had (connecting under the battery) and plug it into the probe (which I've yet to obtain) or is this unnecessary?

3) The anti-blowback device the firm which I bought the kit from sent me was too big (80mm diam) I measured the fitting at the end of the AFM and it was 70mm. The firm has now sent me a 72mm piece instead - will this fit or should I get them to find a 70mm one?

Sorry for all the boring LPG questions to those not interested in such things! And thanks for any help anyone can offer!

Andrew

Post Tue Jan 24, 2006 9:13 pm

bump .i'm interested as well

Post Tue Jan 24, 2006 10:24 pm

I've fitted the boss for the lambda sensor to one of the downpipes so that it points horizontally inwards around the area of the anti roll bar. Took the pipes off to fit it. No real point in using the OE socket, beacause you don't need the lambda running when on petrol, you need the signal output to feed to your gas ECU, and I don't know if the non cat ECU will power up the lambds heater relay properly.
The "cat flap" anti blow back device on mine fits over the part of the AFM where the hose to the throttle body normally clamps on, secured by three grub screws and sealed with silicon rubber. The rubber air hose then clamps on to the engine side of the "cat flap". Took me a couple of goes to get the correct size one.
The whole thing moves the air filter housing about 25mm towards the front of the car, which needed alterations to it's mountings.

Post Wed Jan 25, 2006 7:56 am

Thanks for the reply,

I can get on with fitting the lambda probe now, which is a great help as I was a bit confused about that. Next weekend will be fun trying to cram everything into the engine bay - like finding somewhere suitable for the vaporiser!

Next up I'll be posting lots of dumb questions about electrics!

Post Wed Jan 25, 2006 8:16 am

Sorry, now for a really, really stupid question: What is LPG?

Post Wed Jan 25, 2006 8:53 am

klu99apm wrote:Thanks for the reply,

I can get on with fitting the lambda probe now, which is a great help as I was a bit confused about that. Next weekend will be fun trying to cram everything into the engine bay - like finding somewhere suitable for the vaporiser!

Next up I'll be posting lots of dumb questions about electrics!

I've got the vapouriser on the chassis rail on the LH side, about half way along. Just needed an extension/re-routing of the power steering feed pipe to the pump.
Solenoid/filter is on the front of the LH suspension turret, right at the top.

Post Wed Jan 25, 2006 8:55 am

Martin323i wrote:Sorry, now for a really, really stupid question: What is LPG?

Liquid petroleum gas - The stuff that comes in bottles that you run your barbecue off.

Post Wed Jan 25, 2006 12:15 pm

Brianmoooore wrote:
Martin323i wrote:Sorry, now for a really, really stupid question: What is LPG?
Liquid petroleum gas - The stuff that comes in bottles that you run your barbecue off.

Ahh, OK. Why would you want to do this conversion? Increased Power/Torque. Better mileage?

Post Wed Jan 25, 2006 12:19 pm

Martin323i wrote:
Brianmoooore wrote:
Martin323i wrote:Sorry, now for a really, really stupid question: What is LPG?
Liquid petroleum gas - The stuff that comes in bottles that you run your barbecue off.
Ahh, OK. Why would you want to do this conversion? Increased Power/Torque. Better mileage?

LPG is around 34.5p per Litre, Petrol around 89p per Litre, can you guess !!!

Post Wed Jan 25, 2006 1:02 pm

Brianmoooore - I saw some pictures of your installation on here a while ago. My main concern is getting the vaporiser somewhere reasonably accessable so it can be tuned etc.

Do you find with yours that once its set up thats it, or does it need tuning every now and then (also my Romano vaporiser has two large black adjusters to adjust (one at the top, one at the bottom) - I thought there was supposed to be only one?)

I'll have some electrical questions by the weekend no doubt!

Post Wed Jan 25, 2006 1:57 pm

kam-325i wrote:
Martin323i wrote:
Brianmoooore wrote: Liquid petroleum gas - The stuff that comes in bottles that you run your barbecue off.
Ahh, OK. Why would you want to do this conversion? Increased Power/Torque. Better mileage?
LPG is around 34.5p per Litre, Petrol around 89p per Litre, can you guess !!!

So can you guys buy LPG at petrol stations in the UK?

Post Wed Jan 25, 2006 2:42 pm

Yep. From some Petrol Stations, mainly in the bigger cities and towns, and also from Gas supply depots like BOC, Calor, Fuel Bunkers.

Post Wed Jan 25, 2006 8:15 pm

klu99apm wrote:Brianmoooore - I saw some pictures of your installation on here a while ago. My main concern is getting the vaporiser somewhere reasonably accessable so it can be tuned etc.

Do you find with yours that once its set up thats it, or does it need tuning every now and then (also my Romano vaporiser has two large black adjusters to adjust (one at the top, one at the bottom) - I thought there was supposed to be only one?)

I'll have some electrical questions by the weekend no doubt!

The adjuster on my vapouriser is easily accessable where I've put it on the chassis rail, and I find that once set it stays OK between services.
I'm not familiar with the Romano vapouriser but the two adjustments will be the main adjustment and an idle bleed, which allows a small flow of gas with no engine vacuum. In practice, I think the idle bleed can be shut off with a closed loop system.
What closed loop system do you have? i.e. What is the make of the gas ECU?

Post Wed Jan 25, 2006 8:29 pm

kam-325i wrote:
Martin323i wrote:
Brianmoooore wrote: Liquid petroleum gas - The stuff that comes in bottles that you run your barbecue off.
Ahh, OK. Why would you want to do this conversion? Increased Power/Torque. Better mileage?
LPG is around 34.5p per Litre, Petrol around 89p per Litre, can you guess !!!

Could say we run LPG out of concern for the enviroment, as LPG produces far less harmfull emissiopns than petrol (LPG car will pass emissions test for cat equipped cars without a cat fitted), and there is a world excess of production of LPG as a byproduct of petro and diesel production. Up to a short while ago a lot of the UKs LPG was flared off (burnt) at the refinery, and still is in the muiddle east.
LPG also greatly reduces engine wear, as LPG does not condense out in a cold engine like petrol and wash the oil of the bore walls, and it doesn't contaminate the oil with nasties like petrol does. Also has a higher octane rating of around 110, so on a LPG only engine the comp ratio can be increased.
Downside of LPG is a slightly reduced engine power (not noticeable, in practice), and, on UK LPG, a 20% reduction in MPG. This is because LPG is 20% less dense than petrol. i.e. Weight for weight, the MPKg is the same. French LPG has a different mix of gasses, and you get most of the 20% back over there.

Main reason for running LPG though is the half price fuel costs.
Another benefit is MPG on LPG is much less affected by "spirited" driving than on petrol, so there's no excuse not to....

Post Wed Jan 25, 2006 8:31 pm

Brianmoooore wrote:
Martin323i wrote:Sorry, now for a really, really stupid question: What is LPG?
Liquid petroleum gas - The stuff that comes in bottles that you run your barbecue off.

LPG: Liquified Petroleum Gas

Click here for a list of petrol stations in your area http://www.boostlpg.co.uk/

Post Wed Jan 25, 2006 9:31 pm

What closed loop system do you have? i.e. What is the make of the gas ECU?

I've got a leonardo ECU. I also bought the interface lead and software for completeness but I guess it'll probably need setting up professionally for the first time.

Can I fit a lambda probe designed for any old car as I'll be cutting the plug off it anyway and wiring it up independently - I presume the actual probe is the same for all cars (I ask as theres some cheap ones on ebay!)

Post Wed Jan 25, 2006 9:48 pm

Go for a four wire lambda sensor. Mine was ageneric one from a local motor factors. Hasn't given any trouble in 4-5 years.
Leonardo is the best, and easy to set up with a laptop, even the first time.

Post Mon Jan 30, 2006 5:11 pm

IÃƒ”š've got everything done on the kit now except the electrics, which I have a few questions about so I hope somebody in the know can answer them for me and IÃƒ”š'm nearly there with my LPG kit!

1) WhereÃƒ”š's the best place to get a switched live from? (Should this run through a relay or will it be okay)

2)Can I wire the red/white wires from the fuel injectors through one relay to deactivate them, or do they need separate relays?

3)Where do I pick up the Throttle Position Senor wiring? I found a plug with some wires from it directly below the Ãƒ”šÃ¢â‚¬Ëathrottle mechanismÃƒ”š' where the throttle cable attaches Ãƒ”šÃ¢â‚¬”a is this where I pick up the TPS from Ãƒ”šÃ¢â‚¬”a any ideas what colour it should be?

4)IÃƒ”š've bought (and fitted the boss for) a 4 wire lambda sensor. From what IÃƒ”š've found on the internet two wires are the heater element and two are signal wires Ãƒ”šÃ¢â‚¬”a which signal wire do I use and what do I do with the other one?

Thanks for any help anyone can offer (please use small words as electrics arenÃƒ”š't my strength!)

Post Tue Jan 31, 2006 12:38 am

klu99apm wrote:IÃƒ”š've got everything done on the kit now except the electrics, which I have a few questions about so I hope somebody in the know can answer them for me and IÃƒ”š'm nearly there with my LPG kit!

1) WhereÃƒ”š's the best place to get a switched live from? (Should this run through a relay or will it be okay)

2)Can I wire the red/white wires from the fuel injectors through one relay to deactivate them, or do they need separate relays?

3)Where do I pick up the Throttle Position Senor wiring? I found a plug with some wires from it directly below the Ãƒ”šÃ¢â‚¬Ëathrottle mechanismÃƒ”š' where the throttle cable attaches Ãƒ”šÃ¢â‚¬”a is this where I pick up the TPS from Ãƒ”šÃ¢â‚¬”a any ideas what colour it should be?

4)IÃƒ”š've bought (and fitted the boss for) a 4 wire lambda sensor. From what IÃƒ”š've found on the internet two wires are the heater element and two are signal wires Ãƒ”šÃ¢â‚¬”a which signal wire do I use and what do I do with the other one?

Thanks for any help anyone can offer (please use small words as electrics arenÃƒ”š't my strength!)

1/ Switched live can come from the + term of the ignition coil. No relay required. The Leonardo harness for this wire also contains the RPM wire (brown), which goes to the coil - terminal.
2/Use the two yellow wires from the Leonardo ECU to cut the feed to the injectors at pin 87 of the main DME (white) relay. This will also disconnect the power to tyhe idle control valve as well, so run a seperate new wire from 87 of the DME relay to pin 2 of the idle control valve in place of the existing one.
3/ You can pick up the TPS switch signal anywhere between the TPS and the ECU. It's a brown/blue wire.
4/Two white wires are for the heater. Earth one and feed the other, via a 7.5A fuse from pin 87 of the yellow fuel pump relay. This will then switch the lambda heater on whenever the engine is running (along with the petrol fuel pump).
Grey wire is the lambda signal earth wire, so earth that as well (by a seperate wire). Black is the signal wire, and goes to Leonardo purple.

Post Tue Jan 31, 2006 9:57 am

Thanks for the exellent reply!

I won't get a chance to wire it all up till the weekend but I can go shopping now for the electrical bits and pieces I need. Hopefully by the end of the weekend my car should be running on LPG

Post Wed Feb 08, 2006 10:02 am

Ok so it wasn't running on LPG by the end of the weekend but it is now!

I've only had it ticking over on LPG but I'll go for a drive later today and check its all working as it should be.

I'm already loving the cheap costs - I filled up with 12 litres of LPG yesterday which only cost me about 4 pounds!!

Big thanks to Brianmooore who has been really helpful on this thread and when I've PM'd him!

Post Wed Feb 08, 2006 9:00 pm

Set the option to indicate a fault if the mixture is lean for too long and go enjoy.
You'll find the gas level indicator (green and red LEDs) is virtually useless. Get into the habit of resetting your trip meter to zero when you fill, and use that instead. You'll find that gas consumption doesn't vary with driving conditions anything like as much as petrol does, so you'll always get about the same miles from a tankfull.
So there's no excuse for not driving with pedal to the metal either.