Cultus VXRi Intake restriction on FF CNG model

aminjafer5441 (Amin Jafer) 2020-02-10 12:42:53 +0500 #1

There is a restriction in the intake after air filter in the FF CNG model. I know it is there to create vacuum for the CNG burner but I believe it restricts too much of air flow especially when driving on petrol. Has anyone tried to remove it and drive the car on CNG? Would it be possible to adjust the CNG flow and remove this restriction to get better breathing for the engine ?

engnr.mubashir (engnr.mubashir) 2020-02-12 17:29:40 +0500 #2

With CNG you won't be able to enjoy both thing you have to sacrifice one thing either CNG or Gasoline.

margallar (margallar) 2020-02-12 18:30:19 +0500 #3

Yep i have removed it with great results, however car can only be used on petrol when it is removed.

You will have to close the hole where cng pipe was attached.

aminjafer5441 (Amin Jafer) 2020-02-13 16:02:06 +0500 #4

Thanks for the info, there is also another restriction right behind the air filter. The opening of the pipe is restricted internally. I was thinking of removing that and not the CNG burner itself. That way I might be able to drive on both CNG and petrol. I'll try to do it and see if there is any effect in performance or economy

aminjafer5441 (Amin Jafer) 2020-02-13 16:04:09 +0500 #5

Agreed but I believe the restriction is too much as the intake is restricted already by the CNG burner and then there is another restriction where the intake pipe connects to the air filter box.

margallar (margallar) 2020-02-13 16:48:16 +0500 #6

Remove both

RehanBhatti (RehanBhatti) 2020-02-13 17:06:19 +0500 #7

Yes. CNG venturi is a big restriction itself.

aminjafer5441 (Amin Jafer) 2020-02-13 17:10:58 +0500 #8

Currently the cost of driving on petrol is too much as cultus isn't fuel efficient which is why I need the CNG option

aminjafer5441 (Amin Jafer) 2020-02-13 17:11:44 +0500 #9

I agree, there should have been an injection system like in liana but then the repair would have been very costly

RehanBhatti (RehanBhatti) 2020-02-13 17:15:06 +0500 #10

CNG gives you false savings always. It ruines your engine end of the day.

margallar (margallar) 2020-02-13 18:53:30 +0500 #11

Shift car to petrol only. You will love the power and fuel average.

Cultus gives 13-18 km/l local and 16-18 on long if tuned right on petrol...

RehanBhatti (RehanBhatti) 2020-02-13 18:59:24 +0500 #12

Yes. Mine is driven on petrol only nowadays. Fully tuned on petrol as well. But it gives 12-13km/l maximum on local.

aminjafer5441 (Amin Jafer) 2020-02-13 19:02:01 +0500 #13

I did think of it but with the ever increasing price of petrol vs CNG it is hard to make this decision. If the petrol price is reduced drastically maybe I'll disable the CNG setup altogether but until then it's difficult. Just to give you an idea, 1300 Rs. of CNG runs approx 220-240KM in city.

aminjafer5441 (Amin Jafer) 2020-02-13 19:09:09 +0500 #14

Exactly that is the issue, the petrol economy is very low.

RehanBhatti (RehanBhatti) 2020-02-13 19:32:11 +0500 #15

Because CNG has screwed the engine already.

margallar (margallar) 2020-02-13 19:42:45 +0500 #16

Cng is actually better for engines compared to petrol.

Low fuel avg is blamed on jammed brakes, bad tune and bad bearings.

RehanBhatti (RehanBhatti) 2020-02-13 20:07:05 +0500 #17

Brakes and bearings are perfect in my case. Tune up might be not top notch. Would you like to give me few tips for best tune up. Please

aminjafer5441 (Amin Jafer) 2020-02-13 20:47:40 +0500 #18

Not really brother
Engine is quite strong and smokeless and power is pretty good for such an old engine as it is 2008 model. Actually there are two different school of thought on the CNG matter. In my opinion the only down side CNG has that it has the potential to harm the Valves due to higher temps if not tuned properly (especially the Valve lash) other than that it is actually a cleaner option to petrol and does not have knocking, carbon build up nor does it dilute/contaminate the engine oil like petrol does when running rich in cold start.
Regardless I actually prefer the power and response of petrol, especially bouncing of the rev limiter once in a while but if only the cost factor was not an issue I would have already removed the CNG setup.

aminjafer5441 (Amin Jafer) 2020-02-13 20:54:25 +0500 #19

You can clean the throttle body, use the Liquimoly fuel system cleaner, inspect the Fuel Pressure regulator this is the main culprit for most petrol cars having low mileage as I myself faced this issue. Check if the vacuum side of the FPR is having petrol in it by removing the little vacuum pipe connected to cylinder number 3 on the engine. If there is petrol or you can see it wet then the FPR is bad and leaking petrol directly into the intake plenum. Then obviously the ignition system need to be checked, plugs, wires coil and distributor Cap and rotor, replace any component that seem worn or damaged. DO NOT HAVE THE INJECTORS OPENED! unless by a very good and professional mechanic as they mostly leak after refitting instead use the Liquimoly fuel system treatment first. Also try using the Liqui moly MoS2 oil additive on next oil change.

RehanBhatti (RehanBhatti) 2020-02-13 21:03:46 +0500 #20

Good points bro. I will check FPR for sure. Thanks