Sunday, February 7, 2010

Whats so scary about fuel injection?

What is there to be scared of, its really not very complex to tune and the system is so basic your atari from the 80s crunches more numbers than the ECU on your scoot!.
Yet for almost 2 years now no tuners in taiwan have really touched FI bikes, most have just offered conversions to switch back to carbs and this has created a wave of misinformation that even i was guilty of falling for.
In short its lack of skill and knowledge thats caused this, not because FI is impossible to tune.

To understand just how serious this is you need to know how big scooters are in taiwan, let me compare:

You know honda civics, in you country (usa, europe, almost anywhere in the west) they are very popular with younger guys (or girls!) and the tuning industry is quite simply HUGE (turbos, engine swaps, superchargers, bodykits etc.) ...... right?.

Well times that by 10 and install that user base on a tiny island and you have taiwans scooter tuning industry!.

There are more scooters in taiwan than people and scooters out number cars by about 5 to 1, though taiwan is small it does have alot of people, i think scooters out number the population by 2.something to 1!.

Scooter tuning is a big thing over here, kids are poor and cant afford cars, so scooters offer them the thrills they need for a price they can afford.

The only people buying the new wave of FI bikes have been older people or people not looking to tune, everybody else has been paying throught the teeth for older models with carbs, in fact the older bikes have demanded higher prices because of this crazy situation!.
It wont last long, our '272' has been doing the rounds in magazines, race events and also attracting attention on the street....... people are learning that FI can be tuned and that FI is indeed the future.

Back to the system itself, its frightfully simple and nothing at all like a modern car.
Modern cars have FI systems that are controlled by amazingly powerful ECU's that are computing many different things at once (air density, temp, fuel quality.......god lots of things) to constantly adapt the fueling and ignition timing to stop the car blowing itself up and to pass emissions while putting out good power.
The Z-125's ecu isnt like this........... its like a casio watch, it doesnt monitor anything but the O2 sensor, when it does bother to crunch the numbers its given back from the O2 sensor, you have been waiting about 5 seconds!.
Ignition timing is fixed and it has no control over it, it doesnt measure the air temp or density, doesnt take into account the engine over heating, its got a set map with about 5 or so variables to change to........ which takes around 5 seconds.

The simplicity of it is a right pain for a tuner like me, but its also a mixed blessing, allow me to explain why:

You can change the injector to a higher flowing one, the ecu doesnt know and carrys on fueling like stock, so if you get the flow rating right you can get it fueling almost any engine setup you want!. 

You can manually adjust the ignition timing, it will never know!.

If its running rich you can enlarge the intake or install a larger throttlebody, it will never know!.

Just plug in an O2 reading wideband (even a narrowband) experiment with different setups until you get it as close to perfect as possible, the standard ECU will carry on fueling with a hitch!.

One annoying problem that cant be fixed is the response, remember i said it switches maps or reads the O2 sensor and takes a while for it to adjust, well your stuck with that.
So you can be going WOT from a dead stop and its riding perfect, that you roll off to about 50% and then go WOT again, it will bog down for a few seconds while it decides to adjust or you can close and open the throttle again.

Annoying i know, until they install a ECU thats faster we are stuck with that.

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