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Gas removal


Shanrad
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Hi ive got a 3.9 discovery. Any issues with removing the gas setup that could create the vehicle to either running like carp or to not start at all? Ive removed mine and iam having alot of issues with it running like carp or randomly wont start at all. When doing the gas removal we also changed the head gasket. Please help. Its now been a month not going and my birthday is next week and was planning to go camping but if it won't running like it should ill be staying home

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V8's love LPG.

If the vehicle runs on petrol it is most likely to be an LPG issue.

If the vehicle runs poorly on both petrol and LPG you have other problems.

Before getting the engine run on LPG it should run perfectly on petrol. Afterwards, you can get the engine to run on LPG.

Bon Courage !

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Sorry about that

Yes iam talk about the LPG. The tank and everything under the bonnet is removed. It didn't run real good on lpg and i was told they wreck the engine so out it goes.

The head gasket was wrecked.i was losing water out the exhaust. It was running fine still until we done the gasket and removed the lpg set up.

Ever since it was all done it would only start when it wanted to and when it did start it ran really rough. Its got me beat

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Anybody know first hand how to check the maf reading with a multimeter? Iam unsure of how to use this device correctly and what settings to have it on. Ive put the red lead into the vma socket and the black into the one that has no label and turned it onto v 20 setting. I then turned the key on,put the red into 35 on the ecu plug and earthed the black but its reading 11.79 which tells me its definitely not right lol. Any help would be awesome. Iam still leaning this side of the discovery and enjoy learning. Cheers

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If not firing then I would check the injector wiring, with lpg it is common to cut these and put a relay in line, without the gas switch installed they may simply be disconnected.

Other option is they used injector 'emulators' though I suspect you have already removed them...

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Check the feed from the ignition coil to the ECU, there's a wire that comes from the coil and joins into the loom by the MAF sensor connector. If the LPG kit had tapped into that for it's RPM input then it may have been disconnected or disturbed. Without that signal from the coil the EFi system will not inject fuel or run the fuel pump after the initial prime. It looks like a thick black wire normally and can be mistaken for an earth. I've lost count of the number of hotwire EFi systems that this particular wire has rendered dead after some work on the engine.

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The vehicle is now running again but still very rough.i had somebody over to help me and they mess with the coil wires when i wasnt around.

 

Its funny that you talk about a wire thats in the maf sensor connector harness. I found an orange and brown wire just chilling on its own so i joined it up to the orange and brown on the maf plug because it had nothing there and was the same color..from what i read its a 12v wire. I had to put an extension of wire in first because it didn't reach the maf. Would this have anything to do with it?

 

There is no wire going to the coil from the maf sensor..its all coming from over the engine. White/green and two white/blue 

Cheers 

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The hotwire loom uses the same colour code more than once, I'd be very wary of joining random wires unless they've obviously been cut and clearly join up with something.

The full wiring diagram is in the tech archive and has been posted before so you can follow the loom.

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When you disconnect the AFM or the throttle pot or most of the other sensors, the ECU uses a default mode to continue running without them. It's actually more common for a faulty sensor, once disconnected, to make the engine run smoother than the other way around.

Did you complete the troubleshooting guide ? That covers off the majority of the wiring and ensures the sensors are in the right ball park.

You need to take a methodical approach to fault finding on these engines, using a "scatter gun" approach just leaves you running around in circles, which, from the posts in this topic seems to be what you are doing at the moment.

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Ive gone back over its all again iam still no better off. I just cant understand how its gone from running great to fixing the head gasket and removing gas and now running like this. Ive had mechanics look at it and auto electricians but they cant work it out (none have ever worked on discoverys before though). 

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It's a bit tedious but can you list all the things you've checked from the troubleshooting guide?

If it's overfuelling like mad and all the sensors check out, if it's been on LPG a long time I'd look at the fuel pressure regulator being stuck (or possibly just mis-plumbed / disturbed) as my next thought (without knowing if you've already checked that).

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Ive replaced and then checked: Throttle position sensor,coolant temp,maf,dizzy and module.

The coil,lead and plugs have done 400ks at a guess. Auto electrician checked the spark and said it was good. Everybody thats heard the vehicle seems to think it sounds like its not running on all cylinders. Ive had the rocker covers off again today and everything in turning over smooth in there plus compression test says its perfect. I did have it running a few days ago (still running bad) but now it won't start. Ive had the bus 1 year and never ran it on LPG. Iam getting plenty of fuel i believe.  My oil now smells of it so ill need an oil change once again id say

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