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View Full Version : Issues Accelerating on Low Revs (only on LPG, not petrol -- dual fuel car)



LaneyCat
23-05-2012, 06:07 PM
I've been searching the forums to see if anybody has experienced my current issue, but I'm just not finding anything, so I thought I'd post.

This thread here:
http://www.aussiemagna.com/forums/showthread.php?t=89354&highlight=lpg+idle+issue, the problem that the original poster asked about is basically the same as my problem, but with one difference.
My car is a 1996 Mitsubishi Magna Altera on dual fuel.
And it ONLY has the issue in low revs and acceleration when its switched to LPG. When its on ordinary fuel, its right as rain.

So when I say low revs, I'm talking 1000rpm and under, generally once the car is running and moving fine, I can switch over to LPG and have no issues, until I either need to pull up to a stop sign/red lights, etc. Then accelerating OUT of the stop horrid, just seems to have no power at all, then will suddenly pull hard and start moving normally, but the low power thing is a bit of a nightmare. I forgot about it when driving up the freeway and got stuck behind a truck, no car would let me change lanes, when I finally could change lines, I accelerated and it was so sluggish. I then remembered and flicked over to petrol and it immediately sprung to life and picked up and accelerated easily.
But given it has LPG, I'd like to be able to use it in every situation, not just for freeway driving, as its a lot more economical.
At the moment I'm somewhat bypassing the issue by simply switching over to petrol everytime I think I migh need to slow down/stop/at traffic lights, etc, and then after accelerating out of the slow/stop, I switch back to LPG, but I don't think I should have to keep doing that if I can fix it.

Hope somebody can help.

I would imagine if it was something like o2 sensor it would do it on BOTH types of fuel, no?

prowler
23-05-2012, 06:42 PM
I would suggest checking the air hoses for holes.

erad
23-05-2012, 07:11 PM
Is the car 'missing'? ie is it chugging? If it is, it is most likely your High Tension leads. LPG is much more demanding on spark quality, and if your plug gaps are too wide, or the lead quality has declined over the years, you will get a miss on one or more cylinders. Once up to speed, it will probably be OK.

The other possibility is that the gas system needs a tune. Take it to a good gas man (if such exists) and get him to check it over. You may be too rich or too lean at low revs. Again, once up to speed it will probably be OK. If you get a backfire, you definitely need to change leads, plugs and get a gas tune.

SH00T
23-05-2012, 07:20 PM
Go and see a gas tech!

Sounds a lot to me the diaphrams have gone in the converter, if the age of the system and the car are a couple years apart, its probably likely, they last 5-10 years...
Problems can start straight away, or build up to where you are now after 3 months or or so, depending how close to the spring the tears are....

SH00T
23-05-2012, 07:28 PM
Oh yeah, and do it soon, if it wont hold idle, and cant accelerate well, it will be running lean, but I dont know if its harmful for LPG engines or not :shrugs: