SGi LPG V8 Issue

My Autogas LPG system is not a happy bunny.

I wondered if it was a low gas issue so I filled it to the neck, but still the same.

I know the pressure is good (I assume it's meant to be pretty high) as I had a sparks problem which was caused by a lead which had come adrift from the little metal clip that keeps it on the plug tip. This eventually damaged a coil pack. All replaced and running mint on petrol.

When I put it all back together, I had a gas leak (LPG) and it was down to the poor circlip. Replaced it with a proper job

No more leaking, but the car is not at all happy on switch over, lumpy and lacking any manner of useable power, hunting, missing and just not good.

Plugs are all recent (covered about 600 miles maybe, same plugs as before when she ran like a watch) LPG system was serviced earlier this year and as above, 600 miles or so driven.

I "did" have to remove the inlet manifold and cable tie the LPG injector pipes up out of the way while I removed the rocker cover to replace the rubber gasket (oil weeping). I made sure it all went back as it came apart, so the only thing I can think of is perhaps (although I was very careful) I may have a bad connection on the injectors.

Anyone ant other ideas before I have to strip it again??

The symptoms are when switched, it sometimes idles ok, but now & then it want's to stall. When revving, the LPG switch on the dash has LED guage, a red LED to show the system is active and another to flash & beep when it is empty, then this doubles up as a fault lamp.

Now here's the thing, the fault lamp comes on when the engine is revved then goes out at idle!

I don't know enough about the system to figure if this is an LPG system fault or an injector fault?

Looking into the inlet, it looks like even if there were only 5 of the 8 LPG injectors working, it would still run, albeit a bit weaker, which may be the case.

BUT, I can't tell if the system is merely multi point or sequential...

It has 8 injectors and therefore 8 sets of wires going to 2 LPG ECU's (mounted nearby where I mounted the coils, is it possible the coils are causing an effect???).

Have I buggered it or is it fixable? I think the latter, but I am not 100% sure what to look for and where to start once I have ruled out dodgy (loose) wiring connectors.

If I had cash to spare, I'd go to the guy in Lossiemouth and get him to plug in and interrogate the system. But right now.... So, any idea's will be gratefully received

Hey @Doo ,
Have you tried disconnecting and reconnecting the lpg ecu from the battery, to see if there is a fault logged?
A friend of mine has a lexus rx300 on lpg, it developed a fault with the fuel tank output solenoid. It was replaced but the fault remained until it was disconnected and reconnected.
Maybe? Other than that, just go back over the repair to see if there is anything that could have been knocked or is just not quite right!!

Whilst mine - 3.5EFi - is via a BLOS gas carb & doesn't have much in the way of electrickery & I manually switch from one fuel to the other I know when the gas is low & the pressure drops as whilst it will run it won't accelerate.
Makes me wonder if you've not got all the injectors working so it's a weak mix. Once you've eliminated all connections & that they're connected where they are supposed to be & not misconnected then it looks like you'll need to get a diagnostic done.
Did you do the service yourself or have it professionally done? If the latter could they tell you if its multipoint or sequential?

On mine a weak battery had lost/corrupted the settings in the LPG ECU.
I reset the thing with its own auto-tuning program and it was fine thereafter.

I would concur with getting the lpg system recalibrated first.....

Some systems lose their settings when the battery is disconnected and need to be re setup again, my OMVL system does, but my Prins doesn't.

Try www.lpgshop.co.uk as they provide software and leads for a vast majority of systems.

I was having battery issues just before this problem appeared, so it's a possibility because I did the plug leads & coil packs at the same time.

I moved the coil packs to the top of the airbag bracket at the front left so they are more or less protected, but easy to get to.

I then made up new leads from 8mm graphite core which are much longer than the old 7mm leads, but they work beautifully on petrol so I don't imagine it's them causing the issues.

When I was doing the wiring for the coils (I had to undo all the tape, trace the coil wires, cut, join with solder & heat shrink) I may have disturbed a wire to the LPG ECU or the injector controllers or even those two funny relays that are next to the fuse box and I have a feeling the go to the vapouriser shut off valve.

I will see if the vapouriser needs drained as well.

As stated, I removed the inlet manifold to access the coils and replace the rocker gasket so it is entirely possible I have nudged a wire off one or more injectors.

It's a PITA but what can you do?

EDIT: the controller switch in the cab, it has the gauge, switch over button (which is left on auto when running on LPG, it switches to LPG when warm) as well as a red LED showing it's on and another that flashes when empty accompanied by beeping and if a fault is present it stays lit. It's confusing that it only seems to stay lit when revved... So I'm leaning towards issue with one or more injectors the more I think about it! But the whole switch is working perfectly so no feed fault or seeming ECU problem.

Most SGI gas systems are capable of storing fault codes - I think it would be good to get hold of the LPG system software and lead and interrogate the system.

Saint.V8 said:

I would concur with getting the lpg system recalibrated first.....

Some systems lose their settings when the battery is disconnected and need to be re setup again, my OMVL system does, but my Prins doesn't.

Try www.lpgshop.co.uk as they provide software and leads for a vast majority of systems.

Click to expand...

I have found an AG SGI interface, but I don't know where the socket is to plug into on my car??

Here's the interface: https://www.lpgshop.co.uk/brands/AG-SGI.html

But not sure where to look for the software for my computer (I have Win 10 and Win 7 so either or) on their site?!

Doo said:

I have found an AG SGI interface, but I don't know where the socket is to plug into on my car??

Here's the interface: https://www.lpgshop.co.uk/brands/AG-SGI.html

But not sure where to look for the software for my computer (I have Win 10 and Win 7 so either or) on their site?!

Click to expand...

Have you looked here....and keep scrolling down the list, there are more files near the bottom - one of them is the AG SGi I believe......

https://www.lpgshop.co.uk/lpg-diagnostic-software/

The diagnostic connection will be close to the LPG ECU or even a port under a cover on the LPG ECU itself.....

Saint.V8 said:

Have you looked here....and keep scrolling down the list, there are more files near the bottom - one of them is the AG SGi I believe......

https://www.lpgshop.co.uk/lpg-diagnostic-software/

The diagnostic connection will be close to the LPG ECU or even a port under a cover on the LPG ECU itself.....

Click to expand...

Thanks for that. I will have a squint tomorrow after the hospital (appointment to see orthopaedic surgeon about the pain in my foot and have a go about not seeing my broken neck ).

I also have an LPG question over on AG about a STAKO tank I want to put on my caravan. I'm trying to figure out what step up/down connectors I need for fitting a standard LPG bottle regulator.... It's all there

Gotta go see a man about a dog!