Fuel Injection Question..

[degrom]

With Fuel injection engines...

If I change the exhaust to a flow better and the air intake to breath better.
Why do you have to Dyno it after all the modifications?

Does the engine management system not compensate for the changes in the system and keep the mixture in balance?

[Kwaka14]

Kawasaki use a throttle position indicator as opposed to an airflow meter so the dyno thing is required, I'm not sure if that applies to all injected bikes but definitely an issue for the ZX12 also

[degrom]

Kawasaki use a throttle position indicator as opposed to an airflow meter so the dyno thing is required, I'm not sure if that applies to all injected bikes but definitely an issue for the ZX12 also

That makes perfect sense!!! So the computer does not calculate the mixture then,it just reads its memory and see what amount of fuel is needed at the current throttle position...

[sAsLEX]

That makes perfect sense!!! So the computer does not calculate the mixture then,it just reads its memory and see what amount of fuel is needed at the current throttle position...

Correct, to make a truly self adjusting system would require lots of sensors and computing power which will add to weight and cost so they don't do it.

[The Stranger]

With Fuel injection engines...

If I change the exhaust to a flow better and the air intake to breath better.
Why do you have to Dyno it after all the modifications?

Does the engine management system not compensate for the changes in the system and keep the mixture in balance?

You don't have to and no, in general the fuel injection won't automatically compensate.

Unless you have a Power Commander (or similar) you can't adjust the A/F ratio anyway.

However, if you do put it on the dyno you can check it's not too lean (unlikely) and if you dyno it with a PC you can probably get better performance from it.

[degrom]

Mmmm...(Kwaka12R) But I am looking at a Honda and this is what the manufaturer is saying:

The essence of this system is the continuous use of several variables to control the injected-fuel quantity. Technically, the PGM-FI is an n-alpha mapped injection system, meaning that the basic variables are the engine speed (n) and the throttle angle (alpha). Based mainly on those measurements, the system looks upon its fuel map for the fuel delivery corresponding to the n and alpha of the moment. The computer then adjusts this fuel delivery according to four additional variables; airbox pressure, engine coolant temperature, intake air temperature and atmospheric pressure.

This process of recalculation of fuel delivery is repeated many times per second to ensure continuously correct mixture for conditions, and to provide optimal performance and remarkably crisp throttle response over a wide operating range.

[The Stranger]

Mmmm... But I am looking at a Honda and this is what the manufaturer is saying:

The essence of this system is the continuous use of several variables to control the injected-fuel quantity. Technically, the PGM-FI is an n-alpha mapped injection system, meaning that the basic variables are the engine speed (n) and the throttle angle (alpha). Based mainly on those measurements, the system looks upon its fuel map for the fuel delivery corresponding to the n and alpha of the moment. The computer then adjusts this fuel delivery according to four additional variables; airbox pressure, engine coolant temperature, intake air temperature and atmospheric pressure.

This process of recalculation of fuel delivery is repeated many times per second to ensure continuously correct mixture for conditions, and to provide optimal performance and remarkably crisp throttle response over a wide operating range.

I think you will find though that the scope of that adjustment is somewhat limited.

An example of a mechanism of which you speak is the O2 sensor in the exhaust. It is designed to keep the A/F ratio optimised for the catalytic converter, not for performance and comes into play only at low RPM. It is there so as the manufacturer can pass their emissions tests.

It is sometimes necessary to disable this to correct the mixture when you set up a PC as the fuel injection will continually try and adjust the ratio back to optimal for the catalytic converter, not the bike.

[vifferman]

Kawasaki use a throttle position indicator as opposed to an airflow meter so the dyno thing is required, I'm not sure if that applies to all injected bikes but definitely an issue for the ZX12 also
That's kind of right... although on the Honda at least, there is a MAP sensor.

The problem with bikes is that the negative pressure in the intake manifold can't be measured accurately when the throttle is wide open, because of the multiple throttle bodies/intakes and the large valve overlap of the engine. Conversely, using just the throttle position sensor doesn't work too well at very small throttle openings. So, (on the VFR at least), the computer uses two different kinds of maps - one for the MAP sensor, and one for the throttle position.
The VFR is also a bit tricky in that the V4 configuration means there are differences in cooling, fuel requirements, so it uses 8 different maps altogether - 2 for each cylinder. The ECU reads data from 9 sensors then determines the fueling from reading the appropriate map's data. If the O2 sensors aren't disabled, it uses those at low revs/small throttle openings (in 'closed loop') mode to determine the fueling directly from the EGO levels. The trouble is, the ECU is set ultra-lean to satisfy Euro3/4/5 limits, so the bike ends up with a lean surge, and an awkward hesitation as it switches from 'closed loop' to mapped mode.

You don't necessarily have to get your bike dyno'd if you change the airfilter and/or zorst - it depends how much of a difference it makes. There are quite large margins built in to the fueling so the engines don't blow up if the owner changes anything. For anything but Harleys (no offence intended, HD owners), the engine is pretty much optimally tuned already, so aftermarket airfilters and zorsts don't actually improve 'breathing' much anyway. If your bike has O2 sensors, then the low revs/small throttle fueling is taken care of already.

However, apart from potentially mental fueling in 'closed loop' there's also usually a mid-range dip built in because the emissions testing (noise and exhaust) is carried out at fairly specific revs, so the manufacturers do stuff to cater for this, so the engine gives the appearance of saving the whales and cooling the planet, but only if you don't look past that sweet spot. If you go for aftermarket ECU-fiddling mods in conjunction with dyno-tuning, you can often get rid of this annoying mid-range dip (subject to mechanical constraints, such as cam profiles). That's a big advantage.

[degrom]

My other question was about Ram Air-Intakes (http://www.kiwibiker.co.nz/forums/showthread.php?t=57918)..

How will it effect the bike if you build a Ram Air-Intake for it?
(It will definitely take away the negative pressure in the intake manifold)

[craigs288]

My brother put a different exhaust on his XT and that is injected but only runs off the TPS. Him and his friend stuck the gas sniffer up the pipe. I can't remember if it was leaner or richer, but they adjusted the TPS position until the exhaust was similar to the original setup.

[Pancakes]

My brother put a different exhaust on his XT and that is injected but only runs off the TPS. Him and his friend stuck the gas sniffer up the pipe. I can't remember if it was leaner or richer, but they adjusted the TPS position until the exhaust was similar to the original setup.

The TPS will be one axis and revs normally the other. Messing with the TPS is a pretty brutal way of fixing fuelling. If it worked it was just by chance that that system happened to be ok with it. Fuelling isn't linear so you can't really just raise or lower the sensor to enrich or lean out the motor and be confident it will work.

[imdying]

It's a typically Kiwi bodge :puke:

[Pancakes]

It's a typically Kiwi bodge :puke:

Yeah until it dies then "that Jap stuff's shit ay bro?"

It's liek when people ask what to do to mod their S2000 (Honda car) and it's the most powerful car/L ever! Methinks smarter people have already had a go at making them fast before they were even built?

[The Stranger]

Methinks smarter people have already had a go at making them fast before they were even built?

Maybe they are smarter people, but there is no doubt that some smart people can obtain decent improvements with very little work.
Just in the process of tweaking the Fazer now. I have 10hp more out of it and know from others that it is easy enough to get another 10. Don't really need it but hey it's not hard to gut the cat and install smaller sub throttle plates.

[imdying]

Yeah until it dies then "that Jap stuff's shit ay bro?"

It's liek when people ask what to do to mod their S2000 (Honda car) and it's the most powerful car/L ever! Methinks smarter people have already had a go at making them fast before they were even built?

Yeah mate, doesn't even have to die though... rough idle (doesn't no it's idling so doesn't use the idle map), heavy gas consumption, flat spots, vibration, all potential results from a misadjusted TPS. To each their own though, but you won't catch me doing it.

[Pancakes]

Maybe they are smarter people, but there is no doubt that some smart people can obtain decent improvements with very little work.

No doubt about that, I just don't think this guy and his mate in the shed bending sensors are the other smart people your talking about and didn't want people to read that and think they'd make gains by fooling the sensors on their bikes.


Just in the process of tweaking the Fazer now. I have 10hp more out of it and know from others that it is easy enough to get another 10. Don't really need it but hey it's not hard to gut the cat and install smaller sub throttle plates.

Yeah people with experience will know what to do and how but that will vary vehicle to vehicle with the S200 being a good example because dozens of reputable tuners found that lots of mods will lose lots of power in these cars. I meant, a new turbo Falcon makes gains just by lifting the airbox but almost nothing with free'er pipes, if you do too much, gain more than 15% from memory and the computer uses the fly-by-wire throttle to lower the torque back to factory.

[imdying]

In their defence, fooling the sensors can potentially have a positive effect. It's just easy to make things worse instead.

[Pancakes]

In their defence, fooling the sensors can potentially have a positive effect. It's just easy to make things worse instead.

Yeah true, lots of simple fixes too if you know what your upto.

[imdying]

They worked better back in the day though, ECUs are getting a lot more sophisticated, and often can tell when you're messing with them :laugh:

[bimotabob]

Hi

Adjusting the TPS to make the bike mixture change also may well change the ignition timing like on my system.
Alpha N systems often need remapping of the std fuel curve before mods are done anyway to get rid of dips etc.


Cheers

[stify]

a new turbo Falcon makes gains just by lifting the airbox but almost nothing with free'er pipes, if you do too much, gain more than 15% from memory and the computer uses the fly-by-wire throttle to lower the torque back to factory.


I see this kinda shit every day(foreman at ford dealership), the "big zorst goes faster" thing, that has got to be one of the worst mods on that car without doin some work to the wastegate.

my cbr600rr with only a pipe on it runs leaner than std, I have a k&n to fit but won't till I have a power commander or such like to compensate for the increased airflow

[delusionz]

Really? I thought it was common knowledge that messing with the exhaust throws out tuning. The very design that is supposed to line up exhaust pulses evenly so 1 sucks out the other.

[Pancakes]

Different with a turbo. Some think to use a tuned lengh runner is better some use a log manifold so it pulses more like a single cos aturbo doesn't spin according to the average gas flow it can be spun high by a pulse then carry enough inertia between pulses. Also, the computers messing your fun up aside the more pressure before the turbo and less after (pressure differential, BIG BORE zorst) the more boost can be passed to pressurase the intake and it will come on boost sooner too. So big bore and front mount (better cooling, again less pressure drop) are the two first points to address in a turbo car. All assuming the computer isn't going to see your tricks and limit power thru throttle control or retarding timing. Sorry, I'm writing fast, I wonder if this will make sense?

The Turbo Falcon computer (Black Oak, better than HAL 9000 I guess) is real smart and has multiple sensor cross referances on it's maps to find out if your cheating it.

[FROSTY]

AND now we go back to the origonal question--why do you need to put it on a dyno.?
You put it on a dyno to quantify the changes.both made and possibly needed
It really is that simple.
Once you get into ram air you are into voodoo art -duplicating the ram air effect on a dyno --I don't know of anyone who is able to duplicate the ram air effect in a dyno room

[FROSTY]

Really? I thought it was common knowledge that messing with the exhaust throws out tuning. The very design that is supposed to line up exhaust pulses evenly so 1 sucks out the other.
Unfortunately dude its er not that simple.
if exhaust systems were made JUST to get best performance then they would be made one way
They are made to pass noise emmission laws and gas emmission laws

[delusionz]

Unfortunately dude its er not that simple.
if exhaust systems were made JUST to get best performance then they would be made one way
They are made to pass noise emmission laws and gas emmission laws

It was a response to bigger is better. Is this what you're saying? If not, no need to argue.

Ofcourse they are also designed to pass noise and gas emission laws, I'm not oblivious to mufflers and catalytic converters...

[Pancakes]

It was a response to bigger is better. Is this what you're saying? If not, no need to argue.

Ofcourse they are also designed to pass noise and gas emission laws, I'm not oblivious to mufflers and catalytic converters...

Thats a kinda rude answer when it does seem you might not understand as much as you think you do delusionz.