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2.5 petrol on lpg

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silverbullet View Drop Down
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    Posted: 06 Sep 10 at 11:59

Has anyone got a gassed 5-pot petrol T4 that works properly? I ask as my converted SA 2.6 T3 (near as dammit the same engine with Motronic) has a hot idle fault that's doing my head in.

I'd be  interested to see what arrangement it's got for the vapour plumbing (mine's on a mixer ring, not gas injection btw) before I go re-working mine or getting a second opinion/re-work at different lpg installer.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hogseye Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 10 at 20:06
i just purchased poptop's westy, its 1994 5cyl on gas, he had probs earlier in the year but its running fine for me (had it 3 weeks) i drove it back from wales to suffolk done about 700km in it no probs. this is my first gas conversion so dont know much about them he will prob be able to answer some questions or if you are going to vanfest it will be in carpark on the sat you could have a look... nick
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 10 at 20:20
Nice one! It's within one year of mine so that'll be close enough alright. Yes I'll be at VF, camped in the 80-90 paddock (it will be the only SA there but I'll put my name in the window anyway)
I'll bring my camera.
Cheers,
Ian
pm for mobile numbers?


Edited by silverbullet - 06 Sep 10 at 20:24
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hogseye Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 10 at 09:16
poptop on t4 forum not here my mistake pm'ed you
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrhutch Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 10 at 11:35
Silverbullet, I've done a few LPG conversions and will be in the brickies camping area if you want some advice - usually use the leonardo/AEB lambda feedback systems - I'll be taking the laptop and leads as well.

I'll be the one that everyone is pointing and laughing at

Hutch
T3 1981 Westy Vanagon - thinks lubricant is a fuel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 10 at 13:26
Nice one. I'll swing by and make myself known!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrhutch Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 10 at 15:48
no probs..  what system have you got  - just so I can make sure I have software...

and "hot idle" - do you mean it won't idle when warm, or gets hot when idling  (possible lean running)
T3 1981 Westy Vanagon - thinks lubricant is a fuel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 10 at 16:10
That's just it. When nicely warmed up, usually when coming off motorway. Temparatures are good so it's not miles out on mixture and I have it set at about 2.5% CO (bluepoint exhaust tester) 
It was converted by gasure. Open loop OMVL induction. I've just had a pointer to check the electrical system, conversation went like this...
Me:
Something that I have neglected to mention is that whenever it tries to stall there's a lot of clicking from the lpg tank (solenoids I guess) as it keeps changing over from gas to petrol and back again,
It goes like this: revs fall off, chugga chugga#click#vroom#click#chug#click#vroom# then stalls...
Always happens when thoroughly warmed up. Should I be checking for a loose electrical connection at the tank?
It never, ever misbehaves on petrol and it doesn't matter how much gas is in the tank. I know when it's really low as it misses/hesitates when you try and accelerate on the motorway.
The one thing I have noticed is that when it starts mucking about, the lights on the controller switch go out and "count back up" to the tank level, like it's actually shutting down the lpg system and resetting to run on petrol, then waiting for a throttle blip to switch over to gas.
Reply:
Faulty power supply/faulty switch box... check all connections feeding the switch box... unplug replug in....
if the lights are going out it must be a power supply or box problem..


Edited by silverbullet - 07 Sep 10 at 16:24
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrhutch Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 10 at 07:37
defo sounds like an electrical feed problem, I had VERY similar issue with Mrs Hutchs new beetle running OMVL (rebranded leonardo)system...

Turned out that the power feed to the controller was spiking, and resetting the ecu - the original muppet had wired the feed from the hazard switch, instead of taking a proper iginition on feed from the fuebox..

What happened in my case was similar symptoms, you could hear the solenoid on the tank clicking and engine kept switching from petrol to gas..  Eventually it burned out a couple of tracks on the PCB of the controller..  I made a new loom with PROPER earths and a proper feed and had to buy a new controller..  Been fine since.
T3 1981 Westy Vanagon - thinks lubricant is a fuel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 10 at 11:10
I had enough last night and started at the engine end and worked back up to the controller.
I found, amongst other things: the hose from the mixer to idle valve (motronic) had been poorly cut and crammed on, looks like a prime candidate for an air leak when warm; loose crimp connectors on the vapourizer solenoid; finally got to the dash end and found the controller earth was a soldered eye but tucked under a dash mounting screw and loose! I also shortened the vapour delivery hose by a full foot, hopefully to improve the throttle / mixture response of the vapourizer.
Still haven't checked the tank connections but...
Took the bus down to Longlife Basingstoke this morning for exhaust fitting (from Woking so good and warm, lots of roundabouts and traffic) and it behaved itself the whole way. Not one hiccup, pop or fart. Big smile


Edited by silverbullet - 08 Sep 10 at 11:12
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrhutch Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 10 at 11:17
good stuff!!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 10 at 12:13
It's a shame that I had to find faults like this from when it was converted. Very disappointing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 13 Sep 10 at 10:47
Well I thought that it was sorted and then after a really good run down to VF it started to play up again in the last 5 miles. Only returned 16-17 mpg too and I was getting 21 on gas before new pipes.
Cruised down at 65-70 with the odd quirt up to 80 but wasn't raggin it.
Then spent all Sat am dropping the new exhaust to re-seal the gasket properly with hi-temp RTV.
Tried to re-set the mixture with the CO meter but not much success. Still goes like a demon so must be too rich (not enough diaphragm tension?) I'm going to get a 2-wire lambda screwed in and wire to a 0-1Volt digi gauge and go from there. Setting up on CO is too tedious and inaccurate.
Strangely my thread on this very subject has disappeared from 80-90 over the weekend...Angry


Edited by silverbullet - 13 Sep 10 at 10:48
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TransPorscher Quote  Post ReplyReply Direct Link To This Post Posted: 14 Sep 10 at 21:46
Interesting read as I'm thinking about getting my 2.5 SA bus converted, although K jet not Motronic. Can't the original conversion company sort this out?

Edited by TransPorscher - 14 Sep 10 at 21:46
Charlie

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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 10 at 09:37
C'mon Charlie, cards on the table!
For my part, personal circumstances dictate that I do not have the opportunity to trapse back up to Cheshire. This was made clear when I got the bus converted and I was given the necessary info to re-tune the system once run-in. Having found what I did, I have no intention of going back.
I'll fix the bigger myself and upgrade it to gas injection when funds allow, which is what I wanted in the first place instead of pissing about with crude mixer rings.
Last night I rigged up a low-cost lambda voltage gauge to get live readings and check it's just on the rich side and never goes lean.
Parts from RS: 2v digital LED voltmeter (£40) Lighter socket switchable/stabilized voltage supply (£5) and a 2 wire lambda sensor from local garage supplies (£10)
Cheap as chips and no need for a £200 lambda gauge Thumbs Up
Screw in sensor to exhaust, run speaker wires up to dash, connect supply and signal wires to voltmeter and Hey Presto! 0.95 v at idle, so it's much too rich for a start.
Now since stoich for petrol is 14.7:1 @ ~0.45v but for lpg is 15.7, if I aim for ~0.45v on gas that should give a safe slightly rich mixture. I think... Confused
When I say ~0.45v I mean anything between 0.2 and 0.7 since this is the "steep bit" of the lambda's response curve where it rapidly switches from lean to rich.
Shizzle, this is complicated proper tech stuff...


Edited by silverbullet - 15 Sep 10 at 15:47
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrhutch Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 10 at 09:55
good work there!

I was looking at doing something similar to the GTi project panel van..  When it went through the emmissions at the MOT station it was running REALLY lean, so need to get it sorted - this probably happened because of the de-cat and remade shorter exhaust..  I don't think that the digijet systems can manage to compensate via the ECU as there is a CO adjustment on the loom..

as this one is just having the simple lambda controlled closed loop system added I would like something on the dash to monitor what the probe is telling the ECU and the LPG ECU
T3 1981 Westy Vanagon - thinks lubricant is a fuel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 10 at 10:12
Hey Hutch,
I meant to get ovet to Camp BY at VF to meet you, but wasted most of Saturday dropping the exhaust off as it was blowing like a good'un from the downpipe flange again. Had to go hunting for some Hi-temp rtv to bodge it and try to set the mix in the field...at least I can set it up something like properly now and then find out if there's another wiring fault. Maybe I'd better just change the dizzy cap and rotor arm to be sure, even though they look perfect (pukka Bosch currently fitted, not crap brand)


Edited by silverbullet - 15 Sep 10 at 10:19
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mrhutch Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 10 at 10:22
no probs!  Would have been good to meet you tho!

Which mixer system do you actually have on there??  the leonardo ones  - often rebadged as OMVL or AEB are really good IMHO

The software is great and you can read the live lambda voltages along with TPS and how much the stepper motor is open/close when the engine is running..

I was thinking of a small basic 12v PC with dash mounted touchscreen to keep the software open  when driving!

T3 1981 Westy Vanagon - thinks lubricant is a fuel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 10 at 10:46
It's an OMVL 90e (I think) running open loop at the mo. I haven't got one showing the Vapouriser close up, but this shows the current set-up. I think the vap delivery hose is still too long, so the vap will have to move to near the PAS pump and that's as good as it'll get.
 


Edited by silverbullet - 15 Sep 10 at 10:48
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Post Options Post Options   Thanks (0) Thanks(0)   Quote silverbullet Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 10 at 10:56
Found one, you can see why I shortened the vap hose to start with!


Edited by silverbullet - 15 Sep 10 at 10:57
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