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Discussion Starter #1 (Edited)
There have been a thread or two about megasquirt lately so i figured id set the record straight here and bring everyone up to date.

First off a history lesson, Alot of what you read about ms is based on what gurov did with the original setups. These boxes got the rpm signal by counting when the individual ignition coils fired. Alot of stuff was written about how this is not the best way possible to do it and I won't, nor do i think gurov would, disagree that its not ideal.

Now that thats out of the way forget about EVERYTHING you've ever read on this site, including the last paragraph, about megasquirt setups. Its a new generation and Im going to tell you everything you need to know right here.

1. rpm signal: Megasquirt 3 will now read your stock trigger wheels, in the stock location, using stock sensors. The developers coded it in about a year back and its worked ever since. This is how my car is running. There are a few advantages to this.

1. obviously no need for an external setup, these are hard for you to fab up in your garage and a bit tempermental if not mounted solidly. All you have to do is patch into the signal wires from the stock angle sensors to the ecu and your set.​


2. this makes the megasquirt the only standalone ecu for our cars that retains sequential injection. In order to keep sequential injection, ecus must have access to a cam sensor. So any setup that requires an external wheel is forced to run a slightly less than optimal batch injection/ignition. This is not a huge deal, but the car responds better with sequential fueling and has a more powerful spark at higher rpms.​


3. This is much more accurate than the previously mentioned (which you shouldnt remember) method.​


2. Throttle body: Megasquirt 3 will NOT power your stock throttle body. The developers have flat out refused to code it do to recent issues with oem electronic throttles causing runaway acceleration. This leaves you with 2 options.

1. You run a cable throttle body. A KA24 tb will bolt right up to the stock manifold, just buy a new gasket for it and done. Then you need a cable, I suggest a sr20 b15 cable. Then you need a gas pedal that has provisions for a cable, i suggest a b15 gas pedal. The b15 gas pedal does NOT direct mount into the spec v frame, but i can sell you an adaptor for $40 or you can make one yourself. Ideally you may need some sort of idle valve, to make warmup and ac a tad more civil. These can be picked up from a junkyard etc.​


2. You use the stock ecu to control the e throttle. This is a decent option as 99.99% of you will not be removing your stock ecu. The only downside to this is you have to keep the maf installed. The reason for this is that the ecu needs to see a certain MAF voltage in order idle correctly. I have a untested workaround for this in my head that may or may not work if someone is willing to try it. The other option would be to install the maf somewhere where you cant see it so its out of sight out of mind.​


3. MAF: Megasquirt 3 will allow you to do away with the maf with a few considerations.


1. The Intake air temperature sensor for spec v is built into the maf. You will need to get a GM IAT sensor ($20ish) to replace this if you want to remove the maf. This is a pretty easy and cheap conversion.​


2. You will need to convert to a throttle cable in order to run without the maf. * see 2.2​


4. Extra features: Here are some of the bigger features that the megasquirt will offer in addition to the obvious fuel+spark. This is not a conclusive list and theres plenty more features availabe, but these are the most common/desired.


1. Launch control/flat shift: This can be wired to use the stock clutch switch. A tad bit of wire trickery is required here but it only requres messing with two wires and i have the diagrams to describe it.​


2. Fan control​


3. Vehicle speed input: shows you your vehicle speed and can be used for speed dependant boost. There are options on how to install this. One is to use the transmission sensor but this will lead to inaccurate speeds when the car spins the tires possibly leading to more boost. The better way is what i am doing which is to take over a abs sensor in the rear wheels. If you dont have abs this isnt an option unless you find a hub and sensor from an abs car. But this way will give you accurate results unless your on a dyno.​


4. Boost control: theres the simple way to do this, which works like pretty much any other ebc. Then theres the boost by speed.​


So how can you get in on this? Well, i can build you one. Theres to main ways to buy a megasquirt, unassembled (requires about 5-6 hours of soldering when your familiar with it) and assembled. Basically what I do is buy the unassembled kit, assemble the board, add a few modifications to make it work better with the sentra (additional hall sensor input and correct jumpers), load a basic firmware and tune from my car, and test to verify that it works. Then I send it to you for pretty much the same price as what it would have cost to get the assembled board. heres a price breakdown:

standard:
megasquirt ecu box = $700
Wiring harness = $125

options:
coolant temp sensor = $20
intake temp sensor = $20
4 bar map sensor = $70 (if you want to run more than 20 psi)
boost solenoid = $50
gas pedal adaptor = $40
gas pedal = $30
accelerator cable = $60

if your interested in a setup that involves no wiring at all and are willing to pull your ecu harness or bring the car to me, I can wire the box in for $250 as well.

Armandotech and I can also tune them if your close to Orlando, FL and interested in that.


If you have any other questions, please either PM me or post up.
 

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+1, listen to this guy.
 

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ah! the real deal at last
thank you

i just went uprev too,
lol, just as Justin left
Yeah, that was one of the big deciding factors for me...I'm not afraid to get my hands dirty and do some learning, but it's always nice to have someone knowledgeable when you run into trouble.
 

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The only downside to this is you have to keep the maf installed. The reason for this is that the ecu needs to see a certain MAF voltage in order idle correctly. I have a untested workaround for this in my head that may or may not work if someone is willing to try it.

I would like to hear more about the work around, would it be like a O2 sim or other type of oscillator?

After reading this I really think I am gonna do this vs the 04+ convert for those of us who do not have 04+ already (me included).
 

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if you have a 02 must you keep the 02 maf
that seems to be a most fragile maf
04 up seems tougher [longer lasting]

on my qr i did just about everything to avoid the early maf

my experience with the swap motor and 02 ecu, which required the 02 maf killed all enthusiasm for the 02 maf
[i went thru three of them in a year of racing]
 

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thanks - this is interesting - should I convert from a Tec 3 to this? i'm thinking about how i'm going to read cam timing on the Tec.
 

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I've lost your number... You think you could help me wire a MS3X in my qg18?
 

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Modified magazine had a blurb about Megasquirt offering a group buy program for plug and play units through DIYautotune.com in this.months issue.

shitty mobile reader app posted this on some kind of smart phone.
 

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Can MS3 do anything with cam phasing? So If i'm just going to splice this into the cars harness then I can keep the Maf and electronic throttle body in the car and hooked up, it just doesn't use it?

Just trying to figure out if I should go with the o4 uprev stuff or go with MS3.
 
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