First of all there are different kinds of Fi system. There are open looped type and the closed looped ones. The difference being that open looped type donot have an O2 sensor while the closed looped type do have the o2 sensor. Hence the ECU in the closed looped FI system bikes get constant readings from the O2 sensor if the bike is running lean or rich, and the ECU increases/decreases the fuel flow accordingly. However, bike with open loop systems do not have any O2 sensor hence their ECU donot get those reading and does zilch!!

The FI system used in R15 is an open looped one however I'm not sure of the ones used in P220FI or RTR160FI or ZMR although I doubt if they'd be closed loop as the cost of closed loop via open looped system is quite high.


Bajaj removed the FI tech from the P220FI to make it less costly the p220FI used to retail at 93000/- and is now available @ 72000/- odd bucks. Although this is only what I know...there may be more to the story. ZMR has cooling problems eh.....well I'm taking a wild shot at this coz I haven't ridden it yet, I think the cooling problem is due to the air cooled nature of the engine coupled with the full fairing. The full fairing restricts the flow of oncoming air towards the engine and hence the engine needs alternative cooling methods(read:Liquid cooling as in R15).



First of all, K%N all by itself does nothing to the bike except giving her more air. This more air if coupled with more fuel flow (via increasing the jets' size in carb bikes or by updating the ECU in FI bikes) gives the engine more fuel to burn. Hence the increase in performance. Although the fuel efficiency will decrease.

@all i think ZMR has closed loop Fi.....

@ Renny
Firstly the whole idea of introducing FI's in india is Global exposure. India is really behind in terms of technology when compared to most of the other countries.
The FI's available in Indian bikes (except ZMR) are open looped where the ECU cant adjust AFR itself.
Also all FI's available here including ZMR cant be re-mapped. Remember technology comes at a price.
In the Indian market for which economy is the highest priority, the manufactures make the best possible at a VFM price tag for higher sales.

All u can do to such FI's is alter the AFR within predefined limits. P220 FI & R15 have specialised tools for the same. Not sure of RTR FI & ZMR FI

1. The ECU CANNOT increase/decrease the fuel flow. The rate of fuel flow depends on the diameter of injector nozzles & number of holes in it. The ECU can only alter the AFR.
2. The cooling problems in ZMR is due to the vertical oil cooler. I guess Bernoulli's principle can be applied in this case. Adding an oil cooler unit is itself a design flaw. Add to that a vertical one.

Some inputs regarding PGM-FI from Honda:

PGM-Fi controls air-fuel ratio by varying the opening duration of the fuel injectors.

PGM-Fi works in closed-loop mainly during engine idling. In closed-loop mode, PGM-Fi uses the signal from one critical sensor, the O2 (or sometimes known as lambda) sensor to attempt to attain an ideal air-fuel ratio of 14.7:1 (stoichometric ratio). An O2 sensor operates by measuring the amount of oxygen left in the exhaust gas. The amount of oxygen is a good indicator of the combustion efficiency and a higher oxygen content will suggest a lean condition and vice versa. O2 sensors are normally mounted on the exhaust manifold (or sometimes called the extractors) and/or catalytic converters (for cars equipped with them) and PGM-Fi uses the O2 sensor reading to bump air-fuel ratio up or down until it gets a reading indicating optimum combustion.

So during engine idling, the air-fuel ratio may initially fluctuate up and down based on O2 sensor readings but should eventually settle to a stable value corresponding to the ideal 14.7:1 ratio. PGM-Fi works in closed-loop mode only during idle or very light accelerator openings.

From moderate to maximum throttle openings, PGM-Fi goes into an open-loop mode. In open loop mode, PGM-Fi ignores the O2 sensor signal but will still use the other sensor signals (air temperature and pressure, TPS etc) to make compensations on the base injector opening values. However for very heavy accelerator positions (indicated by large TPS values), PGM-Fi now gives priority to engine RPM, MAP and TPS sensor readings. RPM and MAP sensors will always be required since they are input parameters for reading the fuel-map. But in open-loop mode, PGM-Fi no longer makes as much compensation for other sensor readings, other than TPS sensor, as in closed-loop mode.

When operating in open-loop then, PGM-Fi will usually be operating in a rich-mode. This will be especially true for JDM vehicles when imported directly from Japan into various countries (whether as used or new cars). The PGM-Fi program will have been originally designed based on the atmospheric conditions in Japan and they will almost certainly be different from the countries into which the cars are imported. Even for truly localized line-ups, a rich condition also normally prevail because the PGM-Fi program would have been originally developed to accommodate for the whole country or sometimes even an entire region and thus would again be based on a large base of 'average' values.

Responding to a very old post. However after reading the recent posts regarding AFR, it would seem installing K&N (if possible) on stock closed loop FI unit would NOT increase fuel flow, rather the FI unit would negate the increase air flow of K&N to maintain factory optimum AFR settings by decreasing air flow instead. Thus K&N would serve no purpose. Does this sound reasonable? No expert, just using common sense.

rahul ur point on zmr cooling failure makes sense!!! my friend did say it had problems with the coolent!!! lolzzz hero honda faced such problems??? cant believe that!!!!

lolzz so no use fitting a filter to the fi tech bikes!!!! something new to learn!!!

There's no coolant in the ZMR. It could be the cooling unit - oil cooling unit.

You can use air filters if the FI system is closed loop.

(or)

If you can adjust the AFR appropriately. (pls correct me if wrong)

As such, nobody on our forum who own a ZMR has reported problems of engine overheating due to cooling issues. I do not understand why people are taking the rumors for granted and discussing it as a failure.

And lolz, there is no coolant in ZMR.

sorry guys no coolent!!!! m new to this world! lolz

Fuel Injection system does not require high compression set up though they might allow the high compression set up by modifications to the combustion chamber design in a way similar to engines with carburetor. Direct Injection systems too allow the use of a higher compression ratio (but that is a different story altogether ).

There is no difference in the functioning of an Air Filter in carburetted or Fuel Injected bike.

Isn't the AFR is varied by changing the mass of Fuel flowing through the Injector ??

In a Closed Loop system, O2 (or Lambda) sensor is of prime importance in maintaining the AFR. The O2 sensor sends continuous signals to the ECU about the type of the AFR burning in the combustion chamber. The ECU then adjusts the AFR depending upon the signals from the O2 sensor by increasing/decreasing the fuel flow through the injector.

Now if there is an increase in the air flow (with fuel flow remaining constant), the AFR will go lean (which will be detected by the O2 sensor). The ECU will then increase the fuel flow through the injector in order to achieve the stoich AFR. Over a few cycles, the mixture becomes stoich.

So, K&N in a closed loop will serve the purpose without any problems pertaining to the AFR which we otherwise face in an open loop FI systems..

Hi guys.. i own a karizma zmr.. i was thinking of installing a k&n filter.. after reading through the thread i understand it does bring in the advantage of more power..

since the ecu tries to maintain the AF ratio increased air intake means increase in the fuel flow rite ?? so more power...

how come this effect is negated in open loop systems ?? is air intake based on exhaust O2 sensors ??

Firstly, in Open loop, the ECU cannot detect if the engine is running Lean/Rich due to the absence of O2 sensor to give a feedback to the ECU.

Secondly, the Air intake is not based on the O2 sensor but it rather depends on the Throttle position. The more you open throttle, more air is admitted into the cylinder and, therefore, more fuel is injected (assuming AFR is maintained at stoich.)

Fitting a Free-flow Air Filter in a closed loop system is a matter of Plug-and-Play.... (experts can correct me if i'm wrong )

No, even for a closed loop system a free flow air filter requires you to make adjustments to the fuel map of the ECU. This is simply because for a closed loop FI system there's a certain limit to how much it can adjust the amount of fuel it injects. On top of that, it has already been mentioned that even closed loop systems go open loop when you really crank the engine to prevent it from burning up. All FI systems richen the mixture at large throttle openings and ignore any O2 sensor if they have it. A free flow filter will screw your AFR when it goes open loop for sure.

Okay now I'm completely confused.

So far I have read two contradictory conclusion in Closed loop FI unit.

1. It does not increase/decrease fuel flow.
2. It increase/decrease fuel flow.

Mega confused.

How does AFR actually works? You know, the ratio can work by
1. increasing/decreasing air flow.
2. increasing/decreasing fuel flow.
3. increasing/decreasing both simultaneously.

Which is it?

If that's the Logic then why wont it work after fitting a Free-flow Air Filter ?? The mixture will burn richer at higher revs which is better instead of burning a lean mixture, isnt it??

One thing is for sure, in a closed loop system, fuel flow does increase with the increase in air flow rates since the system maintains a stoich air to fuel ratio. However, the maximum rate of fuel flowing through the injector depends upon its selection. If HH has Designed the system with a lower Factor of safety to keep costs under check, then...... which i hope HH hasn't done.
But, generally the injector is selected such that it meets even the higher demands. Imagine a case when one of the holes in the injector has clogged due to some dust particle. In that case, the injector still has to meet the fuel flow requirements.