hustler

iTrader: (6)

I assume that loading new .msq files will not change my spark settings for trigger angle...correct?

cjernigan

iTrader: (13)

The spark settings for each MSQ can be different and you can change your spark setting trigger angle by loading a new MSQ. If the spark settings are the same, and they have they same trigger angle. Then no you won't be changing the trigger angle.

Ben

iTrader: (33)

uh yeah it will. sharing complete msq's is a recipe for disaster. there are a lot of settings that can be vehicle and situation dependant. that's why I am not in the habit of sharing msq files.

hustler

iTrader: (6)

something went wacko and my rpm scaling on the VE table is all crazy whacked out, and I was going to reload the DIY basemap.

Braineack

iTrader: (62)

import the fuel and spark table.

Braineack

iTrader: (62)

yep. you're getting smarter!

hustler

iTrader: (6)

I've read through the manual a few times, again yesterday, but it never really made sense until I started working with it. I've given up on road tuning the car for a few days.

hustler

iTrader: (6)

new topic:

Can someone explain PWM to me in lay-man's terms? There is much in the manual to define it. I always interpreted the VE values to be PW considering they adjust the amount of injector pulses open. I know what pulse width is, but now with the "modulation" idea thrown into the mix. I don't understand why the manual suggests setting the PW time threshold to the same value as %. I can't grasp it for some reason.

Braineack

iTrader: (62)

http://www.megamanual.com/v22manual/minj.htm#pwm

hustler

iTrader: (6)

****, I overlooked that page. I'm still stuck though on the concept...why would I want to chop up the injector pulses to begin with? Why not run 1 full squirt per cycle. As long as the fuel atomizes, I don't see why chopping up the PW is beneficial, aside from cutting fuel.

Braineack

iTrader: (62)

its for low ohm injectors. so you don't fry them. PWM quickly pulses them, so there isn't as much current flowing into them. that's about it.

hustler

iTrader: (6)

so by setting it to 100% we're essentially disabling it.

This **** is much more simple than I was making it out to be.

Braineack

iTrader: (62)

100% PWM means it's not limited, so a full 12v would flow to the injectors.


low ohm injectors need some some of current limiting....so they will fry or not flow correctly.

PWM of 50% would make the 12v signal, 6v.

hustler

iTrader: (6)

so pwm reduces voltage (which I don't care about since I have high z) and duty cycle is independant, and adjusted through the VE table?

neogenesis2004

iTrader: (12)

Pulse width modualtion is simply taking a set frequency and changing the length of time something is "on" during each period. The amplitude of it, or voltage in this case, remains the same no matter what the pulse width (pw) is. This in turn is used to determine the Duty cycle (DC) of the solenoid, the injector in this instance. The DC is simply the amount of time it is on divided by the entire period.

So say you have a basic square wave at 50% DC, which is what your injectors "ideally" run on. One period of it looks like this:

|^^^^^^^^^|_____________| Pretend the ^^^^ form a flat line.

You can then change the DC by changing the pulse width. A low pulse width produces a smaller DC, like this:

|^^^|______________________|

As you can see, the frequency remains the same because the period of the wave has not changed. The time it is "On" however is about half, and therefore it now has a DC os 25% or 1/4 of its period.

To get a 75% DC the wave would look like this:
|^^^^^^^^^^^^^^^|______|


So hopefully you can SEE now what exactly it means to MODULATE a pulse width, and how it can be used to control any type of solenoid.

Joe Perez

iTrader: (8)

PWM is a method for approximating an analog voltage using only digital switching. It's much more efficient than linear regulation, assuming you can tolerate some switching noise.

The idea is that averaged over a period of time, flipping a lightswitch on and off very rapidly produces the same amont of average illumination as setting a dimmer to the mid-level position. If you were able to flip the switch several hundred thousand times per second, you'd never notice that it was happening- the light would just seem dim.

In this application, PWM is used to limit the average current going through the injector to a safe level after the initial (full-power) opening period has elapsed. Let's say we want to open a low-impedance injector for 5 milliseconds. You apply full power to it for the first millisecond or so (causing it to draw a lot of current and open very quickly) then you PWM the line for the remaining 4 msec, limiting the amount of power that the injector consumes to a level sufficient for holding it open without burning it up.

neogenesis2004

iTrader: (12)

The above response breaks my rule of not posting in your threads, soley because you actually asked an intelligent question. It is an exception of the rule, I don't plan on it being a normal thing so you shouldn't either :P

hustler

iTrader: (6)

PWM = a concept, not a value
PW = net time period solenoid is activated per activation increment of DC
DC = net activation period throughout the cycle

I think I have it. If not, I give up.

neogenesis2004

iTrader: (12)

PWM is more just a name to call a method of controlling something on and off using a waveform rather than a constant voltage/current supply. Its not a "unit" of anything.

The PW is the length of time it is ON during the period.
Ton = Time on = PW

DC is Ton/Ttotal.

hustler

iTrader: (6)

so essentially PWM is set per injector type as a constant, then PW is the independant variable.