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Thread: Removed CNG Air Blockage From My Civic Today

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    Default Removed CNG Air Blockage From My Civic Today

    I had around 60% air blockage rubber bush installed in air filter box for CNG. The car had excellent pick & mileage with air block.
    Today i had some extra time & just to kill it i decided to remove it set the CNG without the air block. (Caz i had a chul since long that why they block air). i dont like it.
    As i drive on CNG & PETROL both. i felt that the engine feels suffocated when accelerated hard on petrol with air block installed (normal cruise was fine), but runs smoother without it.
    Here's wat i did
    1. removed the air block rubber bush
    2. the engine died on cng (couldnt idle or accelerate)
    3. Opened up the CNG 1.5 turns 4m the T-bolt
    4. Then engine started idling
    5. tuned cng 4m T-bolt at 2500 rpm
    6. fine tuning 4m regulator screw
    7. All done

    I didnt feel any difference in pick & idling is also fine
    The engine runs smoother on higher rpms now
    Abt 5-10% decrease in pick when moving from halt ( but i think i will b able 2 rectify this as well after some hit & trial runs)
    Will post abt any difference in mileage (couldnt check it due to CNG load shedding)
    Previous mileage
    110 kms within city
    190 kms on highway with AC @110 km/hr (never checked on highway w/o AC)

    Can any body here provide me a burner type ventury?


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    if u r able to get back that 5-10% acceleration on launch, im gonna be the next person who does this on his car... keep us posted!
    When the power of love exceeds the love for power, the world will finally know peace=Every man is guilty of all the good he didn't do

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    btw i was able to keep the engine running at idle without air filter box with only venturi at top.
    i think some modification of venturi will solve the problem. i hav that desi type with pipe sticking out in centre.

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    i m thinkin of modifying the venturi by attaching pipe extending downwards. i think it will solve the problem. wat u say?

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    members suggestions r eagerly awaited

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    Your CNG tuning method is what is causing the decrease in performance. You can't set it at a constant 2500rpm run. You have to rev it, listen to the engine noise, make sure it doesn't bog down. You need to tune it at full throttle from around 1000rpm upwards.

    Get the original venturi that has circumferential holes through which gas is sucked into the centre. The pipe sticking out in centre venturi doesn't really perform...
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    yesterday, i got CNG in my car n i did a test. removed the blockage in the air intake... the car barely idled! at 200-300RPM. n it didnt revv past 3500 RPM.

    Then i opened the CNG intake (from T bolt,if thats what it called) this made it revv more and by opening the bolt more, it was able to rev upto 6000rpm. i opened even more but still the acceleration i could was almost half that of normal. max speed achieved in 5th gear was 100km/h. So, today i got the blockage back in :/
    When the power of love exceeds the love for power, the world will finally know peace=Every man is guilty of all the good he didn't do

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    u will ruin ur car. i would suggest that u dont just try stuff. get urself busy or ur car will be ruined. btw do not remove the air filter, if u do so, ur engine will receive unclean air. will destroy ur engine...

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    Quote Originally Posted by MKArsalan View Post
    u will ruin ur car. i would suggest that u dont just try stuff. get urself busy or ur car will be ruined. btw do not remove the air filter, if u do so, ur engine will receive unclean air. will destroy ur engine...
    no, i didnt remove the air filter itself... i removed the extra blockage that is put in cnged vehicles. Offcourse i wont take the air filter element out.
    n i dont think playing around a little bit with air/fuel ratio would ruin my car so easily. offcourse i wont be running it on bad ratios for a long time...
    When the power of love exceeds the love for power, the world will finally know peace=Every man is guilty of all the good he didn't do

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    Quote Originally Posted by ahmadbila View Post
    yesterday, i got CNG in my car n i did a test. removed the blockage in the air intake... the car barely idled! at 200-300RPM. n it didnt revv past 3500 RPM.

    Then i opened the CNG intake (from T bolt,if thats what it called) this made it revv more and by opening the bolt more, it was able to rev upto 6000rpm. i opened even more but still the acceleration i could was almost half that of normal. max speed achieved in 5th gear was 100km/h. So, today i got the blockage back in :/
    I hav been tuning my cng settings since long. i assure u its not a new thing 4 me. if u cant rev ur engine beyond 3500 rpm, then ur settings r not optimal.
    Abt the idle issue that it drops to 200-300 rpm. its normal. u have to set it right.
    Setting ur cng at 2500-3000 rpm is the proper way of manually adjusting the mixture. here is a guide for setting ur gas, with or without blockage (thats wat i do)

    1. Remove air block (optional)
    2. Start ur car & rev it constant at 2500-3000 rpm
    3. Loosen ur t-bolt roughly 3-4 turns but make sure it doesnt come out all the way in ur hand (lol)
    4. the engine will start crumbling
    5. now keeping the accelerator at same place/ tension, start slowly tightening the t-bolt.
    6. At certain tightening ur rpm will start increasing by itself
    7. keep on tightening it slowly
    8. now at certain place the rpm will start dropping again
    9 stop tightening the t-bolt where rpm starts dropping & now start opening the t-bolt more slowly
    10. u will find the place when for abt 1 turn the rpm remains stable (not increasing anymore)
    11. Thats the place.
    12. In other words u just have to find the exact place while tightening where rpm starts dropping. when u find it Open t-bolt by half turn & stop.

    Now check ur settings by hard acceleration. if there is no lag then u r done. if there is lag then open t-bolt by 1/4 (0.25) turn & try again. keep doing it until u feel no lag

    Now fine tune the idle with the knob on cng regulator. same process is done with fine tune screw but replace the word "rpm" with "vibration". the location with least vibration is ur sweet spot.

    Above procedure will let u rev ur engine to red line without any lag.
    The myth of economy or acceleration cng setting is hidden in the half turn of t-bolt where rpm stays constant.

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    & for the info of everybody u can see in 1st post wat mileage i get 4m my civic.
    By doing above method u will have max acceleration as well as economy.
    i normally drive at 110-120 km/hr at highway alongwith occasional jumps to 150 km/hr.
    i m talking about cng not petrol

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    The best solution which i did works best.
    https://www.pakwheels.com/forums/per...intake-cng-diy
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    Quote Originally Posted by roms View Post
    The best solution which i did works best.
    https://www.pakwheels.com/forums/per...intake-cng-diy
    @roms
    i have already seen that thread. u did a good job there.
    but we r talking abt removing the air block all together. b'caz we think that it is not compulsory to block air.
    we r working here for equally treating cng & petrol with just a press on button to convert to cng or petrol.

    I hav also been working on installing a butterfly like u did, but instead of manually doing it with a choke wire, i was converting it to automatic with the help of a linear solenoid which operates when cng regulator wire is powered. as the advancer remains off on petrol & is powered only when u convert to cng & advances the timing.

    btw Sorry 4 the off topic discussion

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    the blockage of air is only necessary to help create vacuum in mani/TB so that cng is sucked in properly. It has nothing to do with pick or economy.
    if ur vacuum is appropriate then there is no need of blockage.
    It all depend on the design of the venturi u install. a good design will create more vacuum. as for our local made venturi design, it is not able to create that much vacuum, thats why we have to opt 4 air blockage.

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    I dont have the air blockage in my car so could it be a reason of pathetic mileage ?

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    Quote Originally Posted by irfan44 View Post
    I hav been tuning my cng settings since long. i assure u its not a new thing 4 me. if u cant rev ur engine beyond 3500 rpm, then ur settings r not optimal.
    Abt the idle issue that it drops to 200-300 rpm. its normal. u have to set it right.
    Setting ur cng at 2500-3000 rpm is the proper way of manually adjusting the mixture. here is a guide for setting ur gas, with or without blockage (thats wat i do)

    1. Remove air block (optional)
    2. Start ur car & rev it constant at 2500-3000 rpm
    3. Loosen ur t-bolt roughly 3-4 turns but make sure it doesnt come out all the way in ur hand (lol)
    4. the engine will start crumbling
    5. now keeping the accelerator at same place/ tension, start slowly tightening the t-bolt.
    6. At certain tightening ur rpm will start increasing by itself
    7. keep on tightening it slowly
    8. now at certain place the rpm will start dropping again
    9 stop tightening the t-bolt where rpm starts dropping & now start opening the t-bolt more slowly
    10. u will find the place when for abt 1 turn the rpm remains stable (not increasing anymore)
    11. Thats the place.
    12. In other words u just have to find the exact place while tightening where rpm starts dropping. when u find it Open t-bolt by half turn & stop.

    Now check ur settings by hard acceleration. if there is no lag then u r done. if there is lag then open t-bolt by 1/4 (0.25) turn & try again. keep doing it until u feel no lag

    Now fine tune the idle with the knob on cng regulator. same process is done with fine tune screw but replace the word "rpm" with "vibration". the location with least vibration is ur sweet spot.

    Above procedure will let u rev ur engine to red line without any lag.
    The myth of economy or acceleration cng setting is hidden in the half turn of t-bolt where rpm stays constant.
    That is soooo helpful! thanks a LOT sir! i'd definitely do that on my car... earlier i used to tune it with hit n trial but now i know the actual technique.

    I gotta ask u a few more things.
    1) The T bolt is usually located between the cng kit and intake pipe, right? my car doesnt have one! on mine, there is a nut/screw sort of thing attached to the top of the cng kit itself. there is a spring below it too. turning it clockwise closes the cng inlet and CC turning opens it. does this change in design effects the procedure that u stated in ur post? or its the same?

    2) The cng kit of my car is full of oil all over it. sumthing like oil seepage (havent washed the engine bay for quite some time now) i know there is some oil in the cng filled which stays in the cng kit and can be removed by a nut below it but that nut is not accessible on my car. sumone told me i need to the kit serviced (by opening it) do i have to?

    3) Its a 2006 honda city idsi. when i take off its air filter cover out (the place where the blockage is installed) there is this oily thing all over the pipes inside, even before the part where the cng inlet is located. is it the cng's oil that is spread inside the air intake box? (there is no oil on filter or anywhere below the blockage) or is it due to engine breather pipe coming to the air intake?

    4) The last thing, as discussed, i ve learned that we need to have a vacuum in the air intake to suck in the cng into the engine, with the blockage removed, how will this vacuum be formed? and if it wont, how does the cng gets sucked in?

    Once again, im really thankful to u for ur highly informative post...
    When the power of love exceeds the love for power, the world will finally know peace=Every man is guilty of all the good he didn't do

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    Quote Originally Posted by fahadsoulsnatcher911 View Post
    I dont have the air blockage in my car so could it be a reason of pathetic mileage ?
    it should not.

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    @ahmadbila
    1. my car also has the same nut screw with spring. it has some name but cant remember it now. its better than the manual t-bolt. its function is the same but it has an added safety feature. it shuts down the cng flow when off & turns ON/open when power is supplied to cng kit.

    2. if ur cng kit has oil then better is to get it serviced properly & also remove ur cylinder & get it cleaned. cylinder must be having a lot of oil.

    3. Yes the oil is 4m the same source

    4. The vacuum is already there. as suction is created by movement of pistons & it sucks air from the air intake & alongwith it the cng is also sucked in. when venturi is fitted on top of TB it is slightly smaller than the TB bore. the small area below venturi between venturi edge & TB wall creates more vacuum, which sucks in the cng from the inlet pipe. Burner type venturies hav holes in that area. thats why cng flow gets more smooth.

    To feel the suction power of the intake, remove air box & try to cover it with ur palm when engine is even idling. u will feel that it will suck ur flesh in.

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    ahann... so that means i gotta get my cng kit serviced and the cng cylinder also cleaned! all of this equipment has a mileage of 200,000kms now... all of that without ANY service, cleaning job watsoever... though engine tuning was done periodically.

    yes i know the vacuum is already there but my question was that is it enough?? given that the blockage is open and all the vacuum can be filled by the air and not the CNG because the intake outlet is much wider... anyways, im assuming YES...
    When the power of love exceeds the love for power, the world will finally know peace=Every man is guilty of all the good he didn't do

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    Apart 4m pick from halt, i m loving the sound & lighter feel.

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