An LPG wiring question

Mon Sep 22, 2008 2:03 pm

After reading as many LPG install threads as possible, I recently embarked upon my own installation

on my '88 325i Touring.
All is as expected fairly straightforward. The problem I currently have is this..... on the main white DME relay, according to all the threads ive read i need to intercept the red/white wire to pin 87 and connect each end to one of the two yellow wires from my lpg ecu.
However on looking at my pin 87 there are two red/white wires ! a big fat one and a thin one.
Can anyone tell me which one to cut? I was wondering if the thin red/white is the feed to the ICV? which may make a lot of sense.
Also, anyone advise the best place to intercept/find the brown/blue from the TPS?
Many Thanks in advance

Mon Sep 22, 2008 2:09 pm

If you follow the small red/white, I think you'll find that it loops back to the fuel pump relay!
You can splice into the TPS wire in the thick loom that goes to the ECU plug. On any later BMW engine, the engine loom has a wiring box where you can make the connection

Mon Sep 22, 2008 2:33 pm

Oh, Ok! I cant see where it goes as it disappears into the black loom stuff, but now you say that I can see another thin red/white going to the fuel pump relay which must be the other end.
If thats the case I need to cut the thick red/white and join its ends to my yellows on the lpg ecu.
Can you recommend a neat way to send power back to ICV? i dont really want to strip off the insulated rubber shield that seems to cover it all the way to the screw in connector under the TPS.
Thanks very much for your help!

Oh also..... where would I find the 'wiring box' you speak of?

Mon Sep 22, 2008 7:43 pm

Ricksta wrote: If thats the case I need to cut the thick red/white and join its ends to my yellows on the lpg ecu.

Yes

Can you recommend a neat way to send power back to ICV? i dont really want to strip off the insulated rubber shield that seems to cover it all the way to the screw in connector under the TPS.

I cut into the loom branch to the ICV, cut the wire, joined a new wire to the piece going to the ICV, and insulated the cut end from the DME relay.
I then bound the new wire to the loom with black tape, over the existing tape.

Oh also..... where would I find the 'wiring box' you speak of?

You won't on a 325 M20 - there isn't one, apart from the one for the injector wiring, and the TPS wire isn't in there!

Tue Sep 23, 2008 3:47 pm

Excellent! Thanks Brian! its nearly there now.

I have downloaded a copy of the leonardo software as my Landi Renzo is apparently a rebadged AEB Leonardo, Would you know how I can make up a suitable lead to connect??? they are all over £40 on the ebay! which i think is a bit steep?

Any help very gratefully recieved

Tue Sep 23, 2008 11:06 pm

I have two different circuits for leads that I can send you, if you PM me an email address.

Wed Sep 24, 2008 10:21 am

PM Sent! Thanks Brian!
Drove home on gas last night!

went to fill up at my local LPG staion this morning and pump out of order!

Wed Sep 24, 2008 4:56 pm

Also................. having connected up all the wires for the LPG ECU I have found that I do not know where to connect the Orange wire from the ECU which I believe is for temperature?
does it go to the blue or brown sensor? and if so which colour wire?

Thanks!

Wed Sep 24, 2008 8:43 pm

My Leonardo's don't have an orange wire, although the instruction manual does refer to it!
Not needed in any case. Temperatures in the UK don't go low enough to cause problems, so leave it disconnected.
Emails coming shortly, BTW.

Wed Sep 24, 2008 10:21 pm

Top Man!! emails recieved thanks very much for that! I see maplin part no's, so can i order all the necessary cable and conectors from them and just assemble as per circuit diagram!

Thanks

will no doubt have more questions later! thanks very much for your help!

Thu Sep 25, 2008 9:22 am

Mine does have the orange wire, but I left it unconnected. In the manual it hints at it being pretty bloody pointless.

Isn't it a nice feeling running about on Gas with the petrol gauge on empty

Thu Sep 25, 2008 9:31 am

Its Absolutely Awesome!!!!!

I havent stopped smiling yet!

I used to have a range rover that my dad had converted when LPG first came out and he gave it to me (it was getting on a bit then) and even that was cheaper to run than my 2.2 Honda.
There is something about fitting it yourself (for a LOT less than they charge) that makes it all the more satisfying!
I will try to get some pics up at the weekend in case they are of any help to others thinking about it, although its still not fininshed yet, I need to tidy everything up now!

Thu Sep 25, 2008 9:36 am

Jon_Bmw wrote: Isn't it a nice feeling running about on Gas with the petrol gauge on empty

Don't have the gauge too low if the fuel pump's still running.

Thu Sep 25, 2008 9:44 am

Brianmoooore wrote:
Jon_Bmw wrote: Isn't it a nice feeling running about on Gas with the petrol gauge on empty
Don't have the gauge too low if the fuel pump's still running.

Good point, the light isn't on yet, so I'm not too worried. Definatly thinking of putting a switch in so I can turn the pump off on long journeys.

Thu Sep 25, 2008 9:50 am

I have my fuel just over a quarter, but i am a little concerned about getting condensation in the tank? as I always kept it full on petrol.

I have already put in a subtle switch to disable the fuel pump! I did that some months ago after some scumbags tried to steal my car unsuccessfully!

Thu Sep 25, 2008 2:59 pm

Never seen an E30 fuel tank rust from the inside out yet.

Thu Sep 25, 2008 3:33 pm

A VERY valid point!!

I had been led to believe that condensation would form on the bare metal walls of a tank and then contaminate the fuel?

Also of course if you run very low on fuel there is the risk of sucking any general debris from the bottom of the tank into the fuel system.

Thu Sep 25, 2008 6:42 pm

Ive been keeping the tank above half since converting to gas and now have the pump on a switch too, nice little green LED on it to remind me to turn it off

It's a temporary measure untill i get a few other mods sorted out, the mk2 will be more subtle...

Mon Oct 13, 2008 4:58 pm

Further to my trying to wire up a connection to a cheap lap top to check the settings,
can anyone confirm the pin numbers to connect from the 9 pin D connector and which of the 4 pins on the lpg ecu these connect too???

Brian moooore kindly sent me a couple of wiring diagrams, but im not sure I fully understand as the pin numbers on one do not correspond ? one says pin 10? and there is surely no pin 10 on a 9 pin connector, unless im missing something.

Thanks for any assistance!