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Old 8th April 2007, 01:28   #1
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Default Very poor average / efficiency on CNG

Hi ,

I guess I will convert my zen on CNG but have small quarries, plz help me to solve those :
1) From lots of thread I cam to know max tank size for CNG is 14 kg, in that you can fill only 10.5 kg, that means if FE of my zen is 15km then after filling tank completely I can go only 157.5 km, is that true ??
2) If I am running car with A.C on, will get CNG smell in cabin ??
plz answer above queries
Thx in advance
JItendra
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Old 8th April 2007, 13:06   #2
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Suggest you go for a smaller tank of 12 Kg rather than 14 its too big and heavy for a zen.

On an average I can fill in 9.5-10 Kg during Winters,In summers around 8-9 Kgs.

My XETA gives me a Mileage of 17-18 without AC and around 11.8-12.5 on petrol, So I guess Your Zen will give more than its existing mileage on Petrol, Considering the Zen is 900 cc engine and Indica is 1405 cc engine.

CNG has slight ammonia smell, but you can hardly smell it since, it is lighter than air so it dissipates immediately incase of any leakage, compared with LPG which is heavier and sticks low incase of a leak. ( Auto-LPG also has a slight odour like normal LPG Cooking gas but much less)

You can never fill in a complete Tank of gas, Max I have got is 10.8 for a 12 Kg Cylinder.

My daily run is 38 Km and I hardly drive on Petrol. The fill on average lasts me 4-5 days

Last edited by wolfinstein : 8th April 2007 at 13:14.
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Old 8th April 2007, 15:23   #3
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Smell inside the cabin can only mean one thing - Leak!

From Wolfenstein's FE figures, i see that he's getting around a 40% increase in mileage when run on CNG.
So, with 10.8 kgs of fuel in a 12 kg tank, considering that ur FE is 20km per kg.
Ur range would be around 220 kms atleast.
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Old 8th April 2007, 16:13   #4
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The distinctive CNG smell comes only from the outside...if its in the cabin that mean you gotta leak.
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Old 8th April 2007, 16:55   #5
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Default Smell in Cabin. of CNG Fitted Zen.

Pl . check using soap water all the joints ,(Ferules) metallic tube connecting the pressure regulator for leakage. on leakage tighten the joint slowly, ( Not over tighten it) , & re check with soap water again. till leakage stops.
The main reason for low FE seems to be only LEAKAGE.
Suneel Gore
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Old 8th April 2007, 17:55   #6
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220km is dissipointing for me, as travels mumbai to pune, mumbai-Baroda ( 450km - one way ) what shd i do ??? wil i get CNG filling centers, out side Mumbai??
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Old 23rd January 2011, 20:25   #7
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Default CNG Cars, low mileage on Petrol

Hi People

I don't want to start another thread for this query, million apologies for highjacking this thread

Recently i got CNG retro fillted in my Santro erlx Xing. The car is running perfectly fine on CNG (touchwood) but when running on Petrol the mileage has dropped. Also when running on Gaoline Mode from the exhaust i can smell smell of Unburnt Fuel.

Would appreciate if CNG cars owners put some light on this?

Thanks

Amit
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Old 30th August 2012, 08:04   #8
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Exclamation CNG mileage issues

Hi, I couldn't find any thread on the specific issue in concern.
I have a 2006 Swift that i recently converted to CNG.
The kit used is a BRC kit, a closed loop system with all original parts.

My car refuses to give me anything more than 13.5Km/KG.
I am desperate, i have tried everything:
  • changed air filter
  • changed spark plugs
  • cleaned throttle body
  • got the kit 'tuned'
  • the CNG installer was also changed my mixer and lambda control module
At this point even he is clueless, and he has a good reputation.

If any of you gurus could help me, i'd be very grateful.
This is a bit urgent as this is a car that my mother uses for her office(not me) and she doesn't understand a thing about cars, i leave for the UK on the 6th of sept for my higher studies, and will be gone for over a year initially. The driver also does not understand when the car has a punctured tire, hence i'd like to sort this issue out before i leave.

Thanks
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Old 31st August 2012, 14:31   #9
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Default Re: CNG mileage issues

Quote:
Originally Posted by HimuraKenshin View Post
Hi, I couldn't find any thread on the specific issue in concern.
I have a 2006 Swift that i recently converted to CNG.
The kit used is a BRC kit, a closed loop system with all original parts.

My car refuses to give me anything more than 13.5Km/KG.
I am desperate, i have tried everything:
  • changed air filter
  • changed spark plugs
  • cleaned throttle body
  • got the kit 'tuned'
  • the CNG installer was also changed my mixer and lambda control module
At this point even he is clueless, and he has a good reputation.

If any of you gurus could help me, i'd be very grateful.
This is a bit urgent as this is a car that my mother uses for her office(not me) and she doesn't understand a thing about cars, i leave for the UK on the 6th of sept for my higher studies, and will be gone for over a year initially. The driver also does not understand when the car has a punctured tire, hence i'd like to sort this issue out before i leave.

Thanks
I have the sample problem with my zen with cng.I have changed all that you have mentioned and more.

im still trying to solve it, currently the issue has been identified as a vaccum leak in the intake manifold(but dont know where exactly). Because of which the idling speed is more and hence more fuel consumption.

You may have to check your idle speed, check vaccum pressure at intake manifold.

Im struggling to solve the issue for last few months, as MASS or other workshops shows least interest in solving the issue.
Vaccum leaks are difficult to identify and requires time and expertise to identify and plug.

To add to your list, As of now i have changed in the last few months,
1. Brake vaccum hose - Rs 1400
2. Idle air control value - Rs 3000
3. Changed all packings - 1500 including labour
4. Cleaned and changed Fuel injector O rings - Rs 1200

Im planning to change inlet manifold gasket this weekend.

If that doesnt solve my problem,
i have only one option left is to change the engine itself :-(
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Old 31st August 2012, 16:13   #10
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Default Re: Very poor average / efficiency on CNG

Why dont you try to spray some wd-40 on your intake manifold,throttle body and all parts you suspect.

I tried the same method when i finally used wd-40 and sprayed on all the joints and found the location as i could see wd-40 disspate immediately,on the other hand if there is a big leak then your idle with wd-40 will either go high or very low as wd-40 enters,but for sure you will locate the leak.

all the best .
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Old 31st August 2012, 17:33   #11
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Default Re: Very poor average / efficiency on CNG

Hi @HimuraKenshin

I tried helping you last time, but we could not make any headway. Can you do one thing as a simple check to confirm whether there is leak of CNG or not? In the morning, instead of any other person opening the car, you open the car & check if there is some foul smell, because if there is any leak some gas will remain in the cabin, & hint at the leak.
Alternatively, try the soap solution test as @novatekcorp has mentioned which could point out to loss due to leak, if any.

However, as you have mentioned
Quote:
she doesn't understand a thing about cars... The driver also does not understand when the car has a punctured tire
Are you sure the driver is not the culprit.

Try a simple test if you know driving. Fill in minimal gas after the next indication of reserve gas (red light on the panel), say 1 kg & drive on your own on road with normal (not heavy traffic) to record the mileage. Probably you will get your answers then & there.

Let me cite you my recent experience... my car had a leak & the cabin would be full of (mild) foul smell when I would open the car (I drive on my own) after 6-8 hours & I was getting a mileage of 15 (aprox) as compared to 20-22 regularly. After I got the leak repaired last Sunday, I changed my route due to heavy rains & water logging in the regular route. The new route had heavy traffic & massive jams, due to which my mileage with 75% AC was around 16 only, but, now I am back to my regular route with lesser jams & heavy but moving traffic & expect my mileage to be around the older figures (I refueled yesterday evening) & the after almost 30 kms on gas the first blinker is yet to go (like what used to happen in pre-leak days).

Hope this helps. But, please also note that basically whatever I am suggesting you is on basis of personal experiences only.

Last edited by CARDEEP : 31st August 2012 at 17:36.
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Old 31st August 2012, 23:35   #12
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Default Re: Very poor average / efficiency on CNG

Quote:
Originally Posted by CARDEEP View Post
Hi @HimuraKenshin

I tried helping you last time, but we could not make any headway. Can you do one thing as a simple check to confirm whether there is leak of CNG or not? In the morning, instead of any other person opening the car, you open the car & check if there is some foul smell, because if there is any leak some gas will remain in the cabin, & hint at the leak.
Alternatively, try the soap solution test as @novatekcorp has mentioned which could point out to loss due to leak, if any.

However, as you have mentioned
Are you sure the driver is not the culprit.

Try a simple test if you know driving. Fill in minimal gas after the next indication of reserve gas (red light on the panel), say 1 kg & drive on your own on road with normal (not heavy traffic) to record the mileage. Probably you will get your answers then & there.

Let me cite you my recent experience... my car had a leak & the cabin would be full of (mild) foul smell when I would open the car (I drive on my own) after 6-8 hours & I was getting a mileage of 15 (aprox) as compared to 20-22 regularly. After I got the leak repaired last Sunday, I changed my route due to heavy rains & water logging in the regular route. The new route had heavy traffic & massive jams, due to which my mileage with 75% AC was around 16 only, but, now I am back to my regular route with lesser jams & heavy but moving traffic & expect my mileage to be around the older figures (I refueled yesterday evening) & the after almost 30 kms on gas the first blinker is yet to go (like what used to happen in pre-leak days).

Hope this helps. But, please also note that basically whatever I am suggesting you is on basis of personal experiences only.
thanks so much for your patient replies.
There is no leak i cheacked with a soapy solution on all joints.
There is one thing that i'd like to tell you:
On petrol, the MAP sensor giver proper reading of the pressure, but as soon as cng is switched on, the map sensor stops giving any reading and drops down to zero and the CIL comes on. i checked this with my OBD kit.
Can this be the culprit as the map and tps are connected to the timind advancer processor.
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Old 1st September 2012, 11:19   #13
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Default Re: Very poor average / efficiency on CNG

Quote:
Originally Posted by HimuraKenshin View Post
thanks so much for your patient replies.
There is no leak i cheacked with a soapy solution on all joints.
There is one thing that i'd like to tell you:
On petrol, the MAP sensor giver proper reading of the pressure, but as soon as cng is switched on, the map sensor stops giving any reading and drops down to zero and the CIL comes on. i checked this with my OBD kit.
Can this be the culprit as the map and tps are connected to the timind advancer processor.
To be honest I never tried out any diagnostic device with my car... but, my car doesn't has the timing advancer even.

To the extent of sounding stupid, I would suggest you to try to disconnect the timing advancer, & then measure the fuel efficiency. I bet at most it would be like driving the old Swift Diesel (not the latest updated model)... when you would be in correct rev range you won't feel much difference, but at lower revs & higher gear you would struggle a bit to pick up speed fast.
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Old 3rd September 2012, 10:42   #14
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Default CNG Kit service

Hi People,

My Santro Xing CNG, has clocked more than 35k, kms just on the CNG. Planning to get the kit serviced. Not really sure, what are the components need to be serviced during the servicing and how much it costs.


BR

Amit
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Old 27th March 2014, 17:33   #15
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Default Re: CNG Cars, low mileage on Petrol

============Recently i got CNG retro fillted in my Santro erlx Xing. The car is running perfectly fine on CNG (touchwood) but when running on Petrol the mileage has dropped. =============


same is the case with me, though I am not sure on this ,but yes, my Honda City gulped up around 3 liters of petrol in 20 kms. Also when running on GAS, it uses up 1000 Rs of Petrol for every 700-800 kms.

Is this normal? I little information here wont hurt
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