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Re: Hero Honda Karizma ZMR
Okay, got some info about the bikey. So question is answered
PGM-Fi operating logic also needs an explanation of what is called the 'open-loop' and 'closed-loop' operating mode for PGM-Fi. Closed-loop means a feedback-loop mode. 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 accomodate for the whole country or sometimes even an entire region and thus would again be based on a large base of 'average' values.
ONE MORE QUESTION
So more FE = a lean mixture
It is bad for my bike, right?
Also, engine is not heating up much.
PSR sir is using the same desnorkeled setup in his ZMA right?
Sir, can you please advice?
Also, how to tag a person in a post here, like tagging using '@' in Facebook?
Wait, again an issue. Just read the quote again
If it adjusts the injector opening based on air pressure value, all my concepts are correct.
Tech savy people, please help.
Really good to see that you have found the answers yourself what you have found above is actually correct. This is a misunderstanding with many that ZMR runs only with a closed loop. But NO, it runs with open-close-open loop depending upon your riding conditions.
Conventional wisdom suggests that engine running in closed loop will compensate for the more air. But the fact is, If the ECU has selected the closed loop mode and the oxygen sensor signals are stable and correct, the ECU could just be commanding a mixture that is simply too lean. The ECU selects the closed loop mode for mainly for idle and low-torque cruising. When in closed loop, the ECU simply reduces the fuel injector control signals to satisfy its desire for a super lean mixture. So yes, when you are running with those mild RPM values the bike is actually running lean. Only when the throttle is opened does the ECU switch to open loop & that is where you are experiencing a significant reduction in FE figure. This super rich (due to more air/more fuel) is also the reason why you would also be feeling a slight increase in power with snorkel removed.
However it is assumed (trusted by many) that the Honda PGMFI system is optimized enough to handle the lean running under low torque conditions. As such your engine is much less stressed at lower RPM & there should not be an issue really. But yes, the program would always have a max & min value for the supply of both fuel and air. Therefore something (mostly air) going beyond the control limit would result in ECU error. You would know as the engine would start behaving abnormally.
Originally posted by vishnurajanme
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Okay, got some info about the bikey. So question is answered
PGM-Fi operating logic also needs an explanation of what is called the 'open-loop' and 'closed-loop' operating mode for PGM-Fi. Closed-loop means a feedback-loop mode. 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 accomodate for the whole country or sometimes even an entire region and thus would again be based on a large base of 'average' values.
ONE MORE QUESTION
So more FE = a lean mixture
It is bad for my bike, right?
Also, engine is not heating up much.
PSR sir is using the same desnorkeled setup in his ZMA right?
Sir, can you please advice?
Also, how to tag a person in a post here, like tagging using '@' in Facebook?
Wait, again an issue. Just read the quote again
If it adjusts the injector opening based on air pressure value, all my concepts are correct.
Tech savy people, please help.
what you have found above is actually correct. This is a misunderstanding with many that ZMR runs only with a closed loop. But NO, it runs with open-close-open loop depending upon your riding conditions. Conventional wisdom suggests that engine running in closed loop will compensate for the more air. But the fact is, If the ECU has selected the closed loop mode and the oxygen sensor signals are stable and correct, the ECU could just be commanding a mixture that is simply too lean. The ECU selects the closed loop mode for mainly for idle and low-torque cruising. When in closed loop, the ECU simply reduces the fuel injector control signals to satisfy its desire for a super lean mixture. So yes, when you are running with those mild RPM values the bike is actually running lean. Only when the throttle is opened does the ECU switch to open loop & that is where you are experiencing a significant reduction in FE figure. This super rich (due to more air/more fuel) is also the reason why you would also be feeling a slight increase in power with snorkel removed.
However it is assumed (trusted by many) that the Honda PGMFI system is optimized enough to handle the lean running under low torque conditions. As such your engine is much less stressed at lower RPM & there should not be an issue really. But yes, the program would always have a max & min value for the supply of both fuel and air. Therefore something (mostly air) going beyond the control limit would result in ECU error. You would know as the engine would start behaving abnormally.
still it is not good for the engine...
I was just correcting Bibhudatta's words.
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