No, the stock ECU will only allow a flow rate of XXX which it calcualtes from the TIME the injector is open vs. the size of the injector provided in the software, which you can set.
It is set up for 30 pound injectors to run full duty cycle. If you require bigger injectors, you have to remove the time limitation that the pulse width is open.
There are a number of ways to do this by "lying" to the computer....but with the limitation removed, it is more "true".
For example, if you need a pulsewidth of 10MS, based on the size of the injector, the stock ECU will cut you off at 6MS, creating a lean condition.
Before the pulse width hack was written people would simply lie to the computer to "fake it out" to get what they mean. This is the primary reason for after market systems.
Also, the VE tables on a stock system only run to 5400, another advantage to the after market systems. HOwever, with the EV (extended volumetric tables) software, you can take it to 6400 on the stock ECI, another example of where the stock software is catching up with after market systems.
I am learning tuning, I am a novice, but what I print, I know is true.
I have never heard of this before. To my knowledge the ECU reads a value for injector size that describes how long it takes 1 injector to flow 1 gram. So sec/gram for 1 injector. if you have a 30 lbs injector operating at the rated pressure then a 30 lbs injector takes .264 seconds. This is the maximum flowrate and that's at around 85% duty cycle.
If you add bigger injectors and don't change the value then obviously the ecm is tricked like you say, but even if you change the valve. Why would there be a setting to limit the flow to a certain amount? The ECM doesn't "know" what the right hex value is for this number (in this case HEX264 = 108) it just takes that number and uses it. It's jsut a big old calculator and does calculations, nothing else. I fail to see how there would be a max flow restriction in the system. The only restriction I see is tha max pulsewidth the injector can operate at.
I worked with an engine simulator:
this simulator can re create any engine condition from maniflold pressure, temp, O2, etc.... It has a check engine light, AC on/off, basically there is no condition that can't be recreated on the bench.
As you can see, although blurry, when an engine analyzer is hooked to it you can see the pulse with increase as the TPS knob is turned up to X% throttle.
As the TPS goes up the pulse with on the engine analyzer goes up accordingly.
In the software we are using, Tuner Cat, there is a field to put in your injector size. When that field is changed, you can see on the engine simulator that the pulse with goes up and down when the injector size is increased or decreased.
Now, if the injector is too small the pulse width will hit the wall and not increase say for example over 70% throttle. If the injector is too big, it will limit the pulse width to less than adequate. The stock computer, without the limit, is designed to deliver what a 30lb injector can deliver at max delivery.
When a new program is introduced with the pulse width cap eliminated, you can see, without question, on the engine analyzer that the pulse width continues to go up... I've seen jumps as much as 50% using the simulator.
So, yeah, that's exactly how it works.
