Megasquirt FAQ, writeup (Updated 30/10/09)

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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby ___Scott___ » Sun May 29, 2016 5:15 pm

I haven't followed MegaSquirt development for a long time so it would be interesting to read more about what's happening now. Especially with respect to how it applies to an ST165.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby MWP » Sun May 29, 2016 5:21 pm

Whats happening now is the MS3-Pro :)
It's worth every penny.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby hoys » Sun May 29, 2016 5:48 pm

For my application the MS2 was worth the money for the time and simplicity. I have all stock functionality (minus the stuff I don't care about like EGR, the fuel pressure control, and knock detection.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby MWP » Sun May 29, 2016 6:23 pm

You don't care about knock protection? :shock:
As for fuel pressure control, it is useful on our cars with the stock smaller fuel return line (I control my pump speed with the ms3).
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby hoys » Mon May 30, 2016 12:53 am

MWP wrote:You don't care about knock protection? :shock:
As for fuel pressure control, it is useful on our cars with the stock smaller fuel return line (I control my pump speed with the ms3).


To be honest, if this engine blows up, I'll swap it. I'm not going to tune the knock circuit on the car where I've spent more on the ECU than the car itself.

The 165 has no variable pump speed control, just a vacuum modulator on the fuel pressure regulator to increase fuel pressure in effort to cool the engine down if it's overheating.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby captaingowa » Thu Sep 01, 2016 1:35 pm

hoys wrote:The 165 has no variable pump speed control, just a vacuum modulator on the fuel pressure regulator to increase fuel pressure in effort to cool the engine down if it's overheating.


It does have fuel pump voltage regulation..
It however, was not implemented to regulate fuel pressure rather conserve the life of the fuel pump.

Voltage regulation was based on Air Flow signal which in turn would signal the Fuel Pump Voltage Regulator to either high or low voltage..
Example:
your sitting in traffic... The pump would run at low voltage, thus conserving the life of the fuel pump.

Most people ditched it when modifying for performance since they did not want any chance of losing fuel pressure via the pump not getting full voltage signal when required.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby captaingowa » Thu Sep 01, 2016 1:43 pm

MWP wrote:You don't care about knock protection? :shock:
As for fuel pressure control, it is useful on our cars with the stock smaller fuel return line (I control my pump speed with the ms3).


Knock detection on MS is one of it's weaker points..
I would not rely too heavily on it unless you plan to calibrate the knock frequency.
Which by the way requires making your engine knock and recording the tone via the programmable ECU.
mmmm detonation.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby hoys » Thu Sep 01, 2016 1:45 pm

captaingowa wrote:
hoys wrote:The 165 has no variable pump speed control, just a vacuum modulator on the fuel pressure regulator to increase fuel pressure in effort to cool the engine down if it's overheating.


It does have fuel pump voltage regulation..
It however, was not implemented to regulate fuel pressure rather conserve the life of the fuel pump.

Voltage regulation was based on Air Flow signal which in turn would signal the Fuel Pump Voltage Regulator to either high or low voltage..
Example:
your sitting in traffic... The pump would run at low voltage, thus conserving the life of the fuel pump.

Most people ditched it when modifying for performance since they did not want any chance of losing fuel pressure via the pump not getting full voltage signal when required.


I thought the AFM circuit was just a pump kill, not a high or low speed switch.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby captaingowa » Thu Sep 01, 2016 2:04 pm

hoys wrote:I thought the AFM circuit was just a pump kill, not a high or low speed switch.


One of its functions does control the Circuit Opening Relay .. or as you say pump kill.

That Vane Air Flow meter or VAF was pretty much the corner stone to Toyota engineers and Engine Management.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby hoys » Thu Sep 01, 2016 2:05 pm

captaingowa wrote:
hoys wrote:I thought the AFM circuit was just a pump kill, not a high or low speed switch.


One of its functions does control the Circuit Opening Relay .. or as you say pump kill.

That Vane Air Flow meter or VAF was pretty much the corner stone to Toyota engineers and Engine Management.


Can you explain how the pump was commanding two speeds in the 165?
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby captaingowa » Thu Sep 01, 2016 2:23 pm

hoys wrote:Can you explain how the pump was commanding two speeds in the 165?


The pump does not command anything since it is only a motor.
http://www.lovehorsepower.com/ToyotaPDFs/22.PDF

View page 5 in the PDF.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby hoys » Thu Sep 01, 2016 2:27 pm

captaingowa wrote:
hoys wrote:Can you explain how the pump was commanding two speeds in the 165?


The pump does not command anything since it is only a motor.
http://www.lovehorsepower.com/ToyotaPDFs/22.PDF

View page 5 in the PDF.


Sorry, I used the wrong word there, I meant to say how the pump is commanded to have two speeds. Looking at the diagrams now.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby captaingowa » Thu Sep 01, 2016 2:33 pm

hoys wrote:Sorry, I used the wrong word there, I meant to say how the pump is commanded to have two speeds. Looking at the diagrams now.


That's fine .. That manual is not specific to any vehicle and is just referencing a 7M engine, though the fuel pump control is the same for the ST165
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby hoys » Thu Sep 01, 2016 2:34 pm

Looks like in my MS I just commanded the pump to always be high. Could easily be put on a programmable output triggered at engine idle speeds. No problems so far so I'm not too worried.

There is also the Fuel Pressure VSV that is normally used to raise the fuel pressure for cold start conditions, but I was interested in commanding it for higher pressure for larger injectors.
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Re: Megasquirt FAQ, writeup (Updated 30/10/09)

Postby captaingowa » Thu Sep 01, 2016 2:44 pm

hoys wrote:Looks like in my MS I just commanded the pump to always be high. Could easily be put on a programmable output triggered at engine idle speeds. No problems so far so I'm not too worried.

There is also the Fuel Pressure VSV that is normally used to raise the fuel pressure for cold start conditions, but I was interested in commanding it for higher pressure for larger injectors.


You can do allot with by programming outputs.
I removed the fuel pump resistor pack, and fuel pump relay, and added my own relay and at the back of the vehicle close to my relocated battery, that was to ensure it received optimal power.
Off of the G1 connector I simply run the signal wire for the Fuel pump relay to the ECU.
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