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joe b
Learner
6 Posts
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 Posted - 27 Sep 2006 : 4:57:41 PM
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Hello,
I was wondering if anyone could help me with this problem. I have a 91 VN V6 Series 2 Commodore Sedan with about 220 000 kms on it. I recently had it converted to lpg (a megagas system) for duel fuel. The problem is it sometimes stalls when you take the foot off the gas and coast ie when you slow down for a set of lights, turn off, or anywhere really, which can be very dangerous. It seems it happens most when I get a straight stretch of road for a few kms then have to slow down. It is fine under power. I have recently changed the thermostat (it runs at about the second bar and opens about the third bar on the temperature gauge). When it has stalled, the gas converter is luke warm to touch though the coolant hoses going in to it, and the thermostat housing are hot (the converter can be hot when driving normally around the city). It doesn't stall all the time when driving around the city, only occasionally when coasting. I've taken it back to the fitter and our efforts haven't been successful in fixing it yet. The next plan is to replace the converter. Has anyone had any similar problems or any ideas on how to fix it? Any help would be appreciated. Thanks.
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trizo
Forum Moderator
3091 Posts
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Posted - 27 Sep 2006 : 9:31:39 PM
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| hhhhmmmmmmm welcome 2 the club mate sounds like you got a nice ol vn there don't know much about the gas but I,me myself have been told 2 steer clear of them with the comms vn-vp in paticular I might start a raging debate in were I get shot down in flames lol but from wat I'v been told sumthing to do with the gas combustion in the motor causes them to bakfire and all sorts of nasty things but then again it may just be here say so who knows might ask the gas installer up the road from my work get bak 2 ya on this!!:P |
3 can keep a secret if 2 are dead |
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mouce
National Driver
1525 Posts
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Posted - 27 Sep 2006 : 9:48:45 PM
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Actually, about the only time you'll ever get a really nasty backfire on gas is if you start the engine with your foot on the throttle. Stay away from the pedal and you should be able to start without too many problems.
If you've got a fetish for starting your car with your foot on the throttle, be prepared to replace your airbox quite a few times.
I have heard that it's possible to modify the inlet tube with a stubby holder so that it won't destroy your airbox, I also believe that it's possible to use a blow-off-valve from a turbo setup to stop your airbox from blowing apart.
As for the issue with the stalling, it may be that it's just not getting hot enough, but something tells me that it's not the source of the problem. There's a big issue that you need to remember with LPG: Gas isn't Gas. Some brands are better than others, and I have heard from several different places that Shell LPG is worth avoiding (it has a reputation for 'clogging' up the converter quickly, aparently it's a very waxy gas.
Since it can stall just about anywhere, check and clean your throttle body (you might be horrified at what's in there, there's a how-to which should help).
There's a chance it's not a problem with the LPG setup and a problem with the car as a whole, can you switch to straight petrol and see if you have the same problems? If so then it might be worth checking a few other bits and pieces.
Try another converter, but don't forget to clean your throttle body...post up with how you go. |
Bite off more than you can chew, and chew like hell - Peter Brock (1945-2006) |
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joe b
Learner
6 Posts
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Posted - 28 Sep 2006 : 6:34:22 PM
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| I have no problems at all on petrol. And yes I am running it on Shell gas. No backfire problems on start up to date though I often do have to turn it over more than when on petrol. Due to get the converter changed in about 2 weeks. Will let you know what happens. |
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mouce
National Driver
1525 Posts
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Posted - 28 Sep 2006 : 6:45:00 PM
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Try BP gas, I've heard good things about their gas. Although, it could just be a dodgy converter, they do exist.
Clean your t/b this weekend if you get the chance, so long as you know how to use a spanner you're set.
http://www.vncommodore.com/forum/topic.asp?TOPIC_ID=394
Try it anyway, even though it runs fine on petrol, clean it anyway. It might help make the car just run a bit better. |
Bite off more than you can chew, and chew like hell - Peter Brock (1945-2006) |
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trizo
Forum Moderator
3091 Posts
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Posted - 29 Sep 2006 : 12:09:20 AM
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wat abiut your miuxture?? may b incorrect?
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3 can keep a secret if 2 are dead |
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pizzadude213
P Plater
58 Posts
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Posted - 01 Oct 2006 : 02:15:18 AM
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well the vn's hate running on gas but they love to run on fuel,
sorry i just say p**s the gas off and just leave it on Fuel.
you will only keep having touble with it otherwise,
seen there getting old but i could be worng. |
go the vn beast!!!!!!!!!!! |
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mouce
National Driver
1525 Posts
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Posted - 04 Oct 2006 : 3:33:10 PM
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Actually...so long as the VN is setup properly to run on gas and the cooling system is up to it, there's no reason to not run it on gas. In fact, when running gas it's quite easy to see a gain in power of up to 8rwkw over petrol.
In some ways running a VN on gas can be a massive advantage. Seeing as the VN is notorious for having a fuel-pump problems, if the fuel pump dies, you can keep driving. |
Bite off more than you can chew, and chew like hell - Peter Brock (1945-2006) |
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joe b
Learner
6 Posts
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Posted - 11 Oct 2006 : 10:19:40 PM
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| Success! (so far). The fitter changed the converter. There is a (recovery or balance?) hose going from the converter to the airbox which provides a vacuum and draws the diaphragm in the converter out to provide the right gas/air mixture on deceleration. The first converter put in had the opening to fit this hose at the back and was not hooked up as the back of the converter was bolted to the car and so the diaphragm was not being drawn out, therefore not enough gas was getting in, hence the stalling. The new converter has this opening on the front and so can be hooked up. No more stalling so far. |
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mouce
National Driver
1525 Posts
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Posted - 11 Oct 2006 : 11:08:48 PM
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| Glad it was so easy. Though I must admit, I'm a tad surprised that the installer didn't pick that up when they were putting it in...sort of question how good they are. |
Bite off more than you can chew, and chew like hell - Peter Brock (1945-2006) |
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