spluttering and loss of power

[jock]

right then my 1192 vouge se is lpg converted but last night i run out of gas so was running in petrol and it was spluttering and loss of power when i put my foot down a little you could feel it judering type and the odd back fire anyone know where to look and poss faults,when i got to the garage and refilled the lpg and run it with lpg on it run perfect?

[Range Rover Blues]

Whne ours did this it turned out to be the ECU :(

Is it a single point or draw through LPG system or a multi-point?

[jock]

i honestly dont know what type of system is installed on my range rover sorry

[hairyasswelder]

i honestly dont know what type of system is installed on my range rover sorry

Just look at it, does it have extra injectors? Is there an adaptor on the inlet? are there extra electrics? can you find any names/fitters labels? fitting certificate?etc.
If you write a description then someone will recognise it, someone might have the same system

I would also check/test the airflow meter,

Hope this helps
Steve

[jock]

right heres 1 for you guys i  put £17 worth of lpg in yesterday at 39.9p p/l and all i got for it was 80 miles is this good or bad?

[MuddyMike]

Thats about 8MPG which sounds bad unless you drove very hard.

Mike

[MuddyMike]

right then my 1192 vouge se is lpg converted but last night i run out of gas so was running in petrol and it was spluttering and loss of power when i put my foot down a little you could feel it judering type and the odd back fire anyone know where to look and poss faults,when i got to the garage and refilled the lpg and run it with lpg on it run perfect?

How old was the petrol in the tank? If it had been sloshing away in there for months it would have evaporated badly and cause very poor running.

Mike

[jock]

right i put £10 worth of petrol in when i bought it 2 weeks go plus i put a further £10 in last week lol as the petrol light was still on? but whats worrying me now is £17 just to do 80 miles around town type of thing and no heavy foot if it carries on like this looks like ill have to part company with it as i cant afford to run it. :(

[MuddyMike]

OK so the petrol is fresh.
The ignition timing for LPG is different to that required for petrol, does the car have an automatic timing advance/retard system fitted? If not it will never run well on both. The backfiring could be due to the ignition being too far advanced for petrol running. This is also a bad thing in that it will damage the sir flow meter. You will also hear the engine pinking when running on petrol.
If it does have an auto timing system then back to the fuel supply
Next step.
When did you last run it on petrol? If it has been run on LPG for a while crud can build up in the bottom of the petrol tank blocking the pickup pipe. Remove a fuel pipe in the engine bay and see if the pump is delivering full flow. Try blowing back down it. If this improves the flow for a short time that proves it is crap in the tank, and you need to remove the tank and flush it out. If not then it could be the pump not giving full flow. Is there air bubbles in the fuel? If so the pickup pipe could have rusted above your somewhat low fuel level, or the fuel line could have become porous. Check for petrol stains along the fuel lines.

The £17 for 80 miles I read as being on LPG, yes? That I roughly worked out to 8MPG on LPG but you are paying half the price of petrol so that equivalent to 16 MPG at petrol cost so that is bad if driving gently. You should be able to get about 90% of petrol MPG on LPG, but to do that the LPG and ignition system must be 100%. Does the exhaust stink of gas? Does it have good spark plugs, leads, coil etc. Has the LPG system been tuned correctly? I put together a V8 110 for my son running on LPG and he achieved far better than your 8MPG, in fact his cost per mile was lower than his pal who ran an old Fiesta. Its hard to help from a distance but first step is new plugs and good leads, forget budget replacements you must use something like Magnacore leads, an ignition spark booster is also required for best MPG.

A lot to think about I know, and many LPG converters do not take these factors into account, then wonder why they get poor MPG and sell the vehicle on.

Take a look at http://www.rpiv8.com/faq-lpg-gen-info.htm#FAQ-LPG it has a lot of useful LPG information.

Mike

[Range Rover Blues]

* mpg on LPG is bad mate, our off roader runs a draw through system which always tend to run a bit lean making them more economical but less powerful.  It can run for about 13p/mile at present, not sure what that is in MPG.  

A single point system will have a large aluminum ring in the air pipe from the filter to the top of the engine plus it's usual to have either a wire running to the lambda sensor or throttle potentiometer.

A simple draw through system is similar but has no electronic control so relies on engine vacuum to control fueling.

A multi point system will either have 2 banks of little valves on a manifold bar with small bore tubes going into the plenum chamber or 8 indicidual valves supported by the same tube, depending on manufacturer.  It will also have a large silver ECU in a cool corner of the engine bay.

Now my LSE can get as bad as 9MPG but for that it has to have the air conn on and tow a 1,500kg caravan at warp2.  It's thirstyer than a single point or draw through but I loose no power whatsoever.

No, on the issue of timing, with the multi point there is no gain in over-advancing the timing.  With our draw through system anout 4-5 degrees gives you back about half the power loss but no noticeable improvement in fuel economy.

LPG burns more slowly than petrol, so you can't rev as easily on standard timing, it can tolerate higher compression ratios that can give problems running on petrol, it burns hotter giving you problems with the plugs, it's harder to ignite so you need a strong spark, good quality ignition components and close tha plugs gap up to 27 thou.

One final note, if Blue backfires on LPG it's a sign that it's burned out an exhaust valve.  The muppet who had it before us skimmed the heads to raise the CR but it would go throughg a valve in 5 minutes on petrol under load and the timing was set at 2-3 degrees :?
Run a good standard CR, standard timing with a BP6ES plug, if you're rich use BPR6EIS and don't re-gap them.  Use Lucas rotor arm and cap as pattern ones often leave a bigger air gap that shows up when on LPG.

Do a compression test.

[Range Rover Blues]

Oh, the LSE did 157 miles on about £26, warp 3, going to the NEC and back if that's any comparison.  She's a 5.0L :D

[jock]

lol all this talk has confused me know,im lost as im new to cars and 4x4s lol plus im now out of work so cant afford to take it to a garage. :(

[Range Rover Blues]

The trat yourself to a Haynes manual, they are not as c**p as the Disco one although everything you need is in the suppliment.

As a rule try to get the engine running on petrol before arsing about with LPG as that takes more to get it burning etc.

[baileys_1984]

on ave we get 60 miles to £10 of gas round town if that helps

[Range Rover Blues]

That's not bad at all.

Jock if you were closer I'd say bring it round but on the assumption it was fine untill you ran on petrol then that's going to be something to do with it.  If it won't run on LPG now either it could be something you don't want to hear.

If it's fine on LPG and bad on petrol then it's muck in your fuel.

[Dave Rogers]

I have a C reg rangie converted to gas, runs around 150 to 180 to 80l of gas on long journeys, laning and sites it's down 80m, but that's LPG for you.

Have a look at the electronics as well, you should see a voltage at the amplifier lead 12v or coil (input 12v output 10v with the engine switched off) if no voltage then it won't run at all. There is a fuel cut off relay under the driver's seat, turn the ignition switch on and off you should hear it click, if it doesn't, run a fused lead direct from the battery to the fuel tank to make the pump work!
Could be a myriad of things combined to solve the fault(s) so keep looking. You say you have plenty of time, best get the bonnet up then!

Regards

Dave