Cough, splutter and stall on LPG HELP!! ;-(

[vq~gangsta]

My VQ has this wierd problem on gas. It works perfect when on petrol, so it's definately the gas playing up.

Every now and then (every day or two) the car sort of cuts out while it's running on gas, and starts coughing and spluttering and looses about 90% power. When i put my foot into it the engine just about cuts out completely, like it's lost ignition almost.

The car will sort of drive OK with minimum throttle, but If i take my foot off the throttle all together and stop, or put it in neutral, it will often stall, especially if i don't give it time for the IAC to up the revs.

Strangely enough, eventually (within 5 minutes) the problem just disappears, and like a snap of the fingers the car leaps back into life like there was never anything wrong with it. I've been trying to work out what specifically makes it good again. Sometimes low throttle driving does it, today it came good when i got up to 70 and started cruising in overdrive.

One thing i have worked out is that pumping the throttle, or heavy throttle doen't help. Feathering it a tiny bit, or just leaving it to idle for long enough seem to be the best remedy i've found. If it really plays up i can flip it to petrol and drive fine, then i can just flick it back to gas a few minutes later and sometimes it comes good again. For all I know, it just comes good again after a random period of time, despite what i do to it.

I did notice once that when it was really playing up, it came good again when i was fiddeling with the idle air mixture screw on the LPG converter (when i screwed it all the way in). Since then i've taken the screw out, cleaned out the inside with carby cleaner, then it didn't have the problem for a few days, but then it started doing it again.

About a month ago I cleaned it out again with start ya bastard and again it came good, but only for a few days. A week later i took the screw out again, and noticed that the spring inside it had gotton all twisten and caught up in the gas convertor.

After realising that the spring was turning with the screw, i lubed up the brass ball on the top of the spring with some vas (shame on your dirty mind!) so that the spring wouldn't stick to the screw and turn with it.

Well i tell ya i thought i had it licked then. It ran like a bloody beauty... for about 10 days (a new personal record) and now it's back to acting like a spoilt little bitch again.
:bang:


HELP ME!!!!!
:ranting:

 

[Pretender]

No go gas

I have the nearly the same symptons with my VN.
Does your gas run through your injectors?
If not I have been told that it is:
1. Unburnt gas in the exhaust (the screw you play with needs adjusting)
2. Same as above but due to bad lead
3. " " due to wrong plugs
4. #%@!@* Cat
5. Too much air (busted filter box so mixture all out or not enough gas)
6. Faulty Coil
7. Petrol not completely shutting off when switched to gas.
8. Gas mixer faulty (or water not hot enough as it passes through the mixer)
9. Water leaking through the mixer into the intake.
10. Electrical fault.
11. Just needs a service to the gas system
All from what I assume are reliable sources except for the water leak (it is definately not this). I have checked the things I can like plugs , leads, Coil, airfilter and box etc. I do need a new cat. As I am not in a position to purchase a new cat or pay for a service, I have been putting up with it. Interestingly it now will do the same occasionally whilst on petrol.
If I could afford to I would get a gas service first as this will eliminate most of the items above and they should be able to pinpoint or fix the cause.
I believe my problem is the cat.
You can just keep trying to adjust the valve and find a compromise between idling well and performance.
If I had an old car with a carby I'd say it was flooding. That's the best description I can come up with as to how mine runs.
Just realised you said the screw on the converter. Look for the valve in the gas line. I was told once, with another gas car, never to adjust the converter screw as this needs to be set using a gas flow meter set for the particular vehicle.

 

[vq~gangsta]

My LPG mechanic told me that when you adjust the idle mixture screw that all it needs to do it get the car idling as good as it can, all that screw does is set how much gas goes through at 0 throttle. It doesn't affect your performance at all.

The screw on the line going from the gas convertor to the throttle body is the power mixture screw. Does the same thing except when your accellerating, not idleing. You basically set this one as low as you can (for economy) up until the point that you start to loose power. I just turn my down until it stops flooding from flooring it too hard before the revs are up. You just gotta make sure you don't turn it down so low that it backfires at high rpm, otherwise the air box busts like a split water baloon. Not Pretty!

Thanks for the tips, i'll start looking into them.
I think i'll start with the coil...
-CHEERS

 

[Pretender]

Now I know the truth about the Converter adjustment. Thanks for that. I might go and play with to see if I can get the idle corrected.