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Old 1st July 2008, 17:38   #1
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Default LPG Tuning

Hi,

I was wondering how many of you would have done Tuning the LPG kit yourself. Infact i did it on my BRC LPG on my 2002 model Corsa 1.4 GLS and made it a mess. Now i get lesser mileage (earlier it was 8-9) at 6-7 km/litre in the city and driving is no longer fun. I have just turned that valve (one with springs), don;t remember how much i have deviated from the standard setting that was done by the BRC mechanic.

If anyone knows or done something on the LPG kit tuning, please share your experience on what you should consider when you do a tuning etc etc

Thanks
Raj
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Old 5th July 2008, 19:38   #2
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Default lpg tuning

hi raj.....there are two tuning points....one is on the vapouriser and the second one will be on the rubber hose which connects vapouriser and air intake line (from near ur air filter). Even if u have disturbed there is no serious issue. If u have disturbed the tuning point on the rubber hose and dont know what was initial position then first u open it fully(that is full air should flow through the hose) and start ur car on gas. Then slowly turn the tuning screw anticlockwise so that air flow reduces. when air flow is very less car will take jerk and stop. so you turn it anti clockwise till the point u feel that engine is running smooth and there i no jerk or vibration. at that point u leave the tuning screw and give accelerator and see response of engine. It should give an instant response should not lag. then take the car for a short trial run and see engine response. If not happy further open the air flow.

If u have turned the tuning screw on vapouriser apply the same principle for that screw....open it only upto that point where ur car engine responses properly to throttle dont open it too much.

u can adjust it back by hit n trial method.

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Last edited by Rehaan : 5th July 2008 at 23:38. Reason: Please see note in post.
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Old 7th July 2008, 11:31   #3
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Quote:
Originally Posted by rammishra View Post
hi raj.....there are two tuning points....

If u have turned the tuning screw on vapouriser apply the same principle for that screw....open it only upto that point where ur car engine responses properly to throttle dont open it too much.

u can adjust it back by hit n trial method.
Hello Rammishra, Thanks so much for a very helpful answer.

Hope you will give me some more points on this regard. I actually wanted to increase my FE, hence did this tuning on LPG. Earlier i was getting 7-8 in the city and 12-13 in the highway (Without AC ON). Now i did some tuning couple of days ago before reading your message (I did trial and error on the tuning screw on the rubber hose) and really started feeling that my city mileage has increased (Looking at the meter on the tank and total kms run).

But i also feel that in the first gear, if i step up the accelerator from the stand still, after reaching say 15-20 km/hr there is hardness in the accelerator pedel. Then i have to change the gear to second. The same happens with the second gear (at 25-30 Km/hr) and all other gears. In the fifth gear , the hardness can be felt once it reached 70-80 km/hr. What could be the reason for this? will it be the loss of power that it is showing? Infact iam a light footer. Should i increase the gas flow when i hit highways to increase the FE or will it be sufficient.

Thanks again for all the help.

RAj
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Old 8th July 2008, 15:44   #4
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Hi Raj,
Looks like you are running very lean mixture
You need to increase the flow of gas by turning the top value clockwise. Then adjust the other value on the vaporiser to run the engine on correct RPM. You can start the engine on petrol and listen to the sound then start on LPG and try to get the same level of sound and vibration. It should not be low, this will cause engine stop at signal lights.
The drop in performance and top speed should not be more than 10 to 15% when compaired to Petrol. This is the point where you get good FE.
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Old 8th July 2008, 22:36   #5
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HI raj,

Its upto you if you feel you are getting good mileage leave it at current position. Only thing to remember is that if you leave tuning screw more open you are going to consume more gas. So just open it as much that your vehicle is running smooth. I didn't undertood what u mean by hardness of accelerator but if gas flow is little less then it may happen that if you accelerate suddenly your engine is not going to respond quickly. actually it is recommended that if you wish to get good fuel efficiency on gas you should press that accelerator softly in all the gears you should avoid pressing too much padel suddenly..
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Old 8th July 2008, 23:40   #6
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My friend's Alto LPG ( dont know which kit ) had a similar problem.
He was not getting the prefect tuning to suit both city and highway driving.
If the setting were done for feul effeciency, then the car would jerk and if the fuel flow was increased, they FE dropped.

He took the car to a local mechanic. The mechanic gave the idea of a " Booseter ". This essentially works by means of giving more amount of fuel. Since then the FE in city has slightly reduced, but overall the car is going smooth.


I tried to inquire more about the " Booster " but could not get any answer.
Can someone throw light on this ?
We are facing a lot of jerking problem in our CNG Maruti 800. I want to fit in that Booster, but first would like to know more about it.
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Old 17th July 2008, 15:39   #7
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Please advice me on what went wrong with the car

Last week i gave the car for servicing the BRC LPG kit and i asked the mechanic not to alter the tuning. But he tuned the kit to get some more mileage and he altered both the valves and it ran perfectly for another 400 KM, which was a long drive from Calicut to Bangalore.

While in the long drive, couple of times car stopped when driving in LPG. Again i started and pressed the accelerator and it runs smooth in LPG. Now 2 days ago, i could start in Petrol and switched to LPG and then it stops, tried twice and no luck. Hence i had to run in petrol. That whole day i ran in Petrol and again, the next day, ie yesterday morning, i ran the car in petrol mode as it was not working in gas. So i almost ran around 50 kms in Petrol. Yesterday evening when i was going back to my home from the office, i started the car and it refused to start. Tried 10 mnts almost to start it and then finally, gave the ignition while in first gear and then it slowly started to show life and after giving acceleration for some time, made it smooth. After reaching home, i increased the LPG flow in the valve and switched to LPG, it worked.
Today morning again i started the car and it refused to start. 10 - 15 mnts of trials did not give any effect. Gave ignition while in first gear and no use. Before going i asked a friend to check it. He came in the afternoon and checked and car started without any issues. Quite strange .

Anybody please tell me what could have gone wrong . I serviced the car at German Motors (the dealer) in Calicut, last month and i serviced the gas kit only last week. Any help is appreciated.

Raj
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Old 26th January 2009, 15:33   #8
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[quote=raj_7703;906891]Please advice me on what went wrong with the car

Hi
know its an old post and hopefully your problem has been solved long back.
But if it hasnt , please do not lose heart. Your LPG kit ll work far better with a closed loop system where it would not need manual intervention.
i am using one since last year and half and i would say its fairly reliable.
Also it would mean a few additions to the kit and cost would be withing 6k.
On MPI cars a closed loop system works better for a longer duration without requriring a little tune. For me it remains good for 6/7.5 k km after which tuneup becomes necesary.
It would mean an addition of a lambda based system which works in tune with the engine ecu , o2 sensor and throttle position etc to derive exact fuel air mixture required . This results in better combustion , better performance and better FE.

It works !
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Old 6th April 2010, 15:46   #9
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Question Determination of Air Fuel Ratio for LPG

What should be the Air/Fuel ratio at LPG side for a Bi-fuel(Gas & LPg) vehicle?
How to determine ?
Should the LPG be rich or lean when compared to Gas?

Can anybody Enlighten me
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Old 6th April 2010, 16:55   #10
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Target AFR for LPG should be around 15.5:1 as compared to 14.7:1 in case of petrol
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Old 6th April 2010, 16:58   #11
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Thanks Psycho, But why it should be leaner than Gas?
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Old 6th April 2010, 18:03   #12
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Some more info from Wiki site, might be helpful Air-fuel ratio - Wikipedia, the free encyclopedia
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