fuel injection

[89blaster89]

ive never really read about it, how does it work on quads? like if you put on a new exhaust and no airlid on a fuel injected yfz 450 how does the jetting work? does it correct its self and let more fuel in when mods are added?

oh and anyone ever read or seen this? Two-Stroke Fuel Injection is Here.... Now! | Two Stroke MotocrossTwo Stroke Motocross

 

[joeak47]

I couldn't get that link to work.

Here's for the do it yourselfer's...

2-stroke Small Engine Fuel Injection Kits

 

[sicivicdude]

ive never really read about it, how does it work on quads? like if you put on a new exhaust and no airlid on a fuel injected yfz 450 how does the jetting work? does it correct its self and let more fuel in when mods are added?

oh and anyone ever read or seen this? Two-Stroke Fuel Injection is Here.... Now! | Two Stroke MotocrossTwo Stroke Motocross

Most "simple" fuel injection systems use a speed-density calculation. Basically, the computer has several inputs to calculate the proper amount of fuel to spray into the engine. Throttle angle (Throttle Position Sensor), manifold pressure (Manifold Absolute Pressure), coolant temperature, and a timing function (generally a pickup somewhere on the engine to tell the computer where the engine is at in its stroke), and occasionally an oxygen sensor (depends on the setup, whether it's closed loop or open loop design).

If the system is designed as an open loop system, the fuel injection is preprogrammed to spray a certain amount of fuel for a given set of parameters (sensor inputs). If it's designed as a closed loop system, the computer will start with a preprogrammed amount of fuel calculation and then adjust that based on what's coming back from the oxygen sensor (thus the name closed loop). Any changes in the amount of fuel that would be necessary in the engine and a closed loop system will compensate because it will know that it's slightly lean (due to more air being allowed through the engine) and will begin to hold the fuel injectors open slightly longer.

An open loop system will NOT compensate for the changes.... It thinks there's still XXX amount of air moving through the engine and will spray only the amount of fuel that would be required if it was still moving that amount of air.

Most of the "tuners" you see are actually not tuners at all.... generally they work by creating a slight offset in the MAP or coolant temperature sensor input into the computer so that the computer "thinks" it needs to spray more fuel and will.

 

[2smoker85]

see I disagree with u in some points due to the Ecu on a atv arent as sofisticated as a new truck or car,all depends on if u want max performance and get the most out of ur atv or are worried about running lean, the Ecu on most atvs do not know what a/f ration is at any condition or time, ecus are loaded with a base map as they would call it and in the map there is a look up table that controls injector pulse width for the combination of throttle position and rpm. The people that load these into the Ecu have tables and sh*t they go by for engine load air intake temp etc this is calculated to determine the amount of fuel being injected. every atv is different some are going to run richer than others right out of the factory. The question is do u want to take the risk of running lean? Installing an exhaust increases engine efficiency and power which increases load which ur map senses but do u want to risk it because MAYBE ur Ecu compensates for the change? leaner engines run hotter, are u 110% sure ur ecu is going to compensate? do u know for sure that the ecu detects that its running hotter or colder? And is going to drop more fuel to cool the engine, we don't know that, unless u have built one, There is no guarantee it will be enough, with a tuner u have a custom map made for ur bike, to me it's reassurance. I have tuners on my truck and motorcycle due to the fact u can't rely on the factories to be 100% reliable.

if in doubt spend the money on a tuner

 

[joeak47]

Neat stuff,but I'll stick with carburetors

 

[sicivicdude]

see I disagree with u in some points due to the Ecu on a atv arent as sofisticated as a new truck or car,all depends on if u want max performance and get the most out of ur atv or are worried about running lean, the Ecu on most atvs do not know what a/f ration is at any condition or time, ecus are loaded with a base map as they would call it and in the map there is a look up table that controls injector pulse width for the combination of throttle position and rpm. The people that load these into the Ecu have tables and sh*t they go by for engine load air intake temp etc this is calculated to determine the amount of fuel being injected. every atv is different some are going to run richer than others right out of the factory. The question is do u want to take the risk of running lean? Installing an exhaust increases engine efficiency and power which increases load which ur map senses but do u want to risk it because MAYBE ur Ecu compensates for the change? leaner engines run hotter, are u 110% sure ur ecu is going to compensate? do u know for sure that the ecu detects that its running hotter or colder? And is going to drop more fuel to cool the engine, we don't know that, unless u have built one, There is no guarantee it will be enough, with a tuner u have a custom map made for ur bike, to me it's reassurance. I have tuners on my truck and motorcycle due to the fact u can't rely on the factories to be 100% reliable.

if in doubt spend the money on a tuner

I know for a FACT that the honda ATV ecm's are open loop. I had the pleasure of riding and working on a rancher 420 EFI. If you lugged the engine down. it would load up, start smoking black, and cut off. No closed loop system is going to do that...

If the ATV has an oxygen sensor, it's a closed loop system and will compensate to a certain degree (until you hit the max pulse width time on the injector or the regulator can't keep the rail pressure up)

I'm not sure, however, how many ATV system's are closed loop.

The tuner you are talking about on your truck is a completely different beast. You're talking about a program that modifies the hex code ECU programming to match new "curves" to the modifications for your vehicle. It a lot more complicated ECU too.

 

[2smoker85]

my point is every atv isnt the same if u want to take the chance of running lean that's fine but for me I would add the tuner for performance and a piece of mind and the reference to my truck was just an example the Ecu on my truck and the tuner are much more complex than a atv.

 

[sicivicdude]

Well, that's why I gave examples and a basic run down of how both types of systems work. If you find an ATV system that has an oxygen sensor, then it SHOULD self compensate for any small changes.

The simple systems will not compensate at all for any changes (like a carburetor with the same jet in it) so you'd have to do that manually (with a tuner most likely)

 

[Agro2424]

I know the new Can-am Maverick runs a closed loop system with a catalytic converter. It's the only one that I am aware of.

 

[DirtDiggler]

EFI on a 2 stroke is overthinking to the extreme. More parts to fail , have to have a true 12v power supply to run it and you still need a damn throttle body as well.
Too much work , just ride the Bastid!!!!!

 

[jus_me]

Srry if i upset anyone but this is BLASTER forum. Not truck or car or your rocket ship.. we r tlkn about 2 stroke's and carburators, not flux capacitor valves. only thing fuel injection will do is cost more $ to something that already works great. IMO..

 

[jus_me]

I have to apologise,, good idea but not for me. ill stick with a carb over fuel injection any day. ..

 

[Larry's Shee]

X-2 I:I If it ain't broke, don't fix it. $$400 + just for kit. I could see that it would be well over 500 before you're done. Would it even add any "Extra" power? Maybe slight driveability improvement.