CNG TUNING How to do it

[hammadmajeed]

can anyone shed some light on the air blocker used on the air intake. Usually tape is used to close half of the intake. What is significance of this ? Do we really need it ? I have santro club 2003 with LZ kit.

[Silicon03]

Dear Experts!
I bought a city iDSi 2005 model, 27K km driven and on Petrol with NO CNG installed
I have installed LandiRenzo CNG kit with 55L cylinder, and LendiRenzo STAP78 Advancer and Emulator.
My car runs fine on CNG giving me 135-155 Km per filling.
As soon as I started the AC, the idle RPM started to decline and finally to 0 and the car switched off. Without AC, everything is fine and also there is no problem on Patrol.

I have replaced the plugs, got throttle body cleaned and then get tuning from CNG installer.. works fine for some days or so then same problem appears....

Any permanent solution to this problem or suggestion for any expert CNG mechanic in islamabad ?

some of the friends at PW suggested to reduce the air flow.

[bmehmud]

@Silicon03
I think a LAMBDA corrector should be installed. One usually does not need a LAMBDA in car but sometimes it it recommended by CNG experts. Anyways get your car checked up from a specialist. I recommend Aneeq CNG at Sixth Road Rawalpindi. They are good at fitting and tuning.

I have a Vitz 2004 and I experienced a loss of pick on A/C after I installed CNG. I preferred to do it myself before going to a CNG mechanic. I started my car and turned my car A/C on. I pulled the accelator cable from the engine and increased the RPM to a considerable speed. I then incrased the gas flow from main srew a bit and start to increase and decrease the race from the cable. At that point the car started missing while i pushed the cable gently. I further adjusted the gas inflow from trial and error to a point where car missing did not appear. I then adjusted the idle speed from another srew location slightly beneath the kit. Car is now giving me good pick and consumption.

[iamadee]

@hammadmajeed
Air intake of you car is desined for petrol normally in cars which do not come ff. In such cases blocking the air is must by doing this you can not only increase the power of your car hence its consumption too.
3 Basics of CNG tech are
GAS=AIR=Current
A bigger intake will require more of GAS and Current to Keep up with.
Instead a smaller intake will lead lesser gas to intake and match the current requirement as well.
Hence increased pickup and milage as well.
This is a pure myth that increasing or decreasing the gas from T switch will lead too better performance or economy unless done precisely keeping the rest of the things in accardance as well.
Every car when set on best performance gives best economy as well.

[hammadmajeed]

@iamdee,

thanks for the reply. Well the logical thing to do is to reduce your intake to such a level that would reduce the inflow of the gas without affecting the pick. Does blocking the half (approx) of the intake with tape ensures the optimal setting for the blockage ? If not, what measures should be taken to accomplish this ? My car had a good pick with my old air filter. I found it dirty so replaced it with a new one. Now my pick has affected and its not as good as it was before. My logic tells me that now that I have installed the new filter, its relatively open and allowing more air to flow, which means more air intake. Now my gas setting was for the low air intake hence i am getting poor pick. It seems to me a wise thing to unscrew the T switch to allow more gas flow or block 3/4th of the intake. What you thin ?

[iamadee]

I think its should be 3/4th or 2/3rd of the intake depending upon the power of the engine. Then adjust the gas from the T screw to the optimal setting and then adjust the idle race screw. It works great i have a rolla with 4AFE engine. i have adjusted it to best perormance and economy follwing the same rule. It gives excellent performance (pick wise and all) with great economy too.

[hammadmajeed]

I have santro, should it be 2/3rd or 3/4th ? Does bigger/powerful engines require relatively more blockage ?

[iamadee]

I'll Suggest 2/3 to be blocked. it should work fine.

[iceman_kimi]

Does anyone know the slang terms for the timing light and feeler guage? Also, how to advance the point in carburettor based engines? Any pics will be much appreciated. Thanks.

[Rawfay]

how much KGs of gas fill in a 55L cylinder?

[HellsGuardian]

the idea of blocking the intake is completly rong, i tried and it dosent word. this isnt the way to block intake,
if u have blockd and then press of pedal, at first less air will flow but when u reach higher rpms like 3000+
the air flow will be same as when it was not bllocked.
only difference is that ur engine is trying ahrd to get that amount of air.

blocked intake:
engine takes more time to reach that rpm

unblockd, it will reach faster
but when both (blocked and unclocked0 reached say 4000
air flow will be the same.

one more thing as engine is desperate to get air, and not easly getting it, engine will suck more gas then normal.

ur problem can be adjusted by the idle knob!
i had same problem but now its great!
ENGINE NEEDS AIR TO RUN. otherwise blockage has bad effects on engine life NVR DO IT!!!
cng may require less air to burn, excess air simply wents out from exhaust.
however if there is too less gas then u may need to increase a bit. but still dont block intake

if blocking was a nice way why landi etc make such a piece of equipement to block a bit of intake

[ansar68pk]

The idea of blocking the air intake is not completely wrong or else my CNG cultus wouldn't come fitted from the factory with a flow restrictor. This flow restrictor is a slightly cone shaped plastic disc with a hole in the middle.

I tried taking out the flow restrictor and the engine died with even a mild push on the accelerator pedal. I tried adjusting the CNG valve but that didn't help much either.

So its a balance between too much air too little air. Too much blockage is bad but some blockage does help.

[iceman_kimi]

@Rawfay
A 55 Liter(or kg) cylinder takes around 8 kg of CNG under normal pressure. If you can find a station which has a higher pressure you may be able to fill half a kg more into it.

For the reference, the feeler gauge is called 'tapet gauge'. I'm not sure about the cost. Will post that too once I get it. It works for gap adjustment of tapets (aka lifters) and/ or the spark plugs.

[salman108]

Blocking the air intake does not always decrease the gas input. the concept is the same as CHOCKING in patrol engines.

Remember CNG kits work with vaccum lining inputs, so chocking the car actually decreases the pressure inside the air intake, thus increasing suck of the vaccum and allowing more CNG to come in.

[Rawfay]

@iceman_kimi

thanks a ton bro! finally someone replied so a 40kg cylinder should fill up around 6.8 to 7kgs of gas. Am i right?

[iceman_kimi]

@Rawfay
You're welcome. I think for a 40kg (or Liters) cylinder would take around 6-6.5 kg with the typical pressure. Why do you ask? If you have a 40kg (or Liters) cylinder you can easily check the amount filled in it at the filling station.

[Rawfay]

@iceman_kimi

i was confused. At the time of installation the guy told me he's putting a 40l cylinder. The other tuning guy told me its 50l. And my friends tell me its 55L. Haha:P

It fills 6.9kgs of gas with max pressure. Now tell me the capacity in liters.

[iceman_kimi]

I think it's a 50L cylinder. My Mehran has a 50L cylinder and it fills up to that mark. If you've not taken out oil from the kit, please do so for a notable increase in capacity.

[TalhaAnwer]

Hi Ansar
I tried multiple CNG workshops (in karachi) for a TAP (advancer) for my 1000 cc margala sedan (Japan) - 3 cylender engine (they call it cultus engine). All of them are insisting that advancers are only for EFI cars. :s
How do i get an appropriate advancer and get that installed?

[crazy_rider]

can any1 tell me the cost of servicing cng kit and cylinder for oil removal as i hav noticed considerable drop in pick n car is missing i instalkl kit last year in july n car is 94 khyber
plz tell me if some1 knows or hav idea
thanx in adv.