Megasquirt tuning sr20det

A place to discuss the systems and methods of tuning Nissan engines.
tr(o)picana
Posts: 13
Joined: Sat Sep 13, 2014 4:54 pm
Car: 91' 240sx redtop
Location: Murrrland

Megasquirt tuning sr20det

Postby tr(o)picana » Sun Oct 12, 2014 9:59 pm

Looking to get feedback who has tuned their sr20det using megasquirt. Am planning on possibly getting one to run e85 in my car :naughty: and as far as I can tell the only weakness for the system is it doesn't like small wires for grounding. Also how beneficial is fully sequential injection over semi or batch, apparently semi has improved idling on the 4g63, but what about full? Lastly, would I be able to set up boost by gear using one?


65ShelbyClone
Posts: 18
Joined: Wed Jan 04, 2006 8:27 pm
Car: '00 Frontier
'72 Pinto Turbo/Megasquirt
'68 Mustang

Re: Megasquirt tuning sr20det

Postby 65ShelbyClone » Sun Feb 08, 2015 12:14 pm

I haven't tuned a Nissan with one, but most of your question aren't specific to the SR20DET anyway.
tr(o)picana wrote:Looking to get feedback who has tuned their sr20det using megasquirt. Am planning on possibly getting one to run e85 in my car :naughty: and as far as I can tell the only weakness for the system is it doesn't like small wires for grounding.
"Small" ground wires aren't a problem so much as the location and number of them. The MS2/v3.0 box I have is extremely sensitive to noise from running low-z injectors with PWM current limiting. That's after proper grounding per the manual and using OEM shielding on the harness. Common problem from what I can gather.
Also how beneficial is fully sequential injection over semi or batch, apparently semi has improved idling on the 4g63, but what about full?
Sequential has some benefits, but they are generally small. It helps with really large injectors when the idle pulse width is actually shorter than the injector's opening time. SEFI also allows for individual cylinder tuning, although doing that requires modifications and instrumentation that most setups don't warrant.
Lastly, would I be able to set up boost by gear using one?
With an MS2 (I think) or MS3-based setup, yes. You'll need some way for the ECU to know which gear the trans is in and that is easier to get with an automatic (meh) than a manual.

tr(o)picana
Posts: 13
Joined: Sat Sep 13, 2014 4:54 pm
Car: 91' 240sx redtop
Location: Murrrland

Re: Megasquirt tuning sr20det

Postby tr(o)picana » Thu Aug 27, 2015 11:22 pm

Thanks for the info clone, and yea haha i guess these questions aren't really specific to an sr20, but some feedback from someone who has done so would be nice. Im kind of a noob when it comes to this stuff, and I know its been awhile since you posted, but could you elaborate on exactly what you mean by sensitive to noise and what that entails? As for boost by gear being tricky, would it be easier to set up boost by speed then, using the vehicle speed sensor? Lastly, did you tune it yourself, how hard was it if so, and what was your experience with tuning beforehand?

65ShelbyClone
Posts: 18
Joined: Wed Jan 04, 2006 8:27 pm
Car: '00 Frontier
'72 Pinto Turbo/Megasquirt
'68 Mustang

Re: Megasquirt tuning sr20det

Postby 65ShelbyClone » Fri Aug 28, 2015 4:17 pm

tr(o)picana wrote:could you elaborate on exactly what you mean by sensitive to noise and what that entails?
"Noise" refers to electrical noise; radio frequency interference(RFI). I it caused by rapid changes in current direction and/or voltage, like the alternator or ignition coil. That RFI induces current in all the wires attached to the ECU. Microprocessors are extremely sensitive to this and RFI can cause false triggers, resets, and even memory corruption in extreme cases. Shielding and good grounds provide paths for the induced current to bypass the ECU.
As for boost by gear being tricky, would it be easier to set up boost by speed then, using the vehicle speed sensor?
I was going to look in TunerStudio to see what the settings and options are, but either TS or the Java Platform it runs under is misbehaving. I'll have to get back to that one.
Lastly, did you tune it yourself, how hard was it if so, and what was your experience with tuning beforehand?
Well, I'm still tuning my car. :chuckle: Acceleration enrichment is a PITA, but tuning transients is always more difficult. Steady-state tuning is easy; drive the car, record lots of data logs, analyze them, tweak the tune, rinse & repeat. Tuning transients is more about achieving what feels right in practice than what looks right on the instruments.

I started with an old MS-I v2.2 back in '05 as a toy of sorts. I put it on a stationary engine with a long serial cable connected to an even older desktop computer. It was an excellent primer for the real deal because I got to do the whole install, tuning, and troubleshooting process on an engine that was expendable. One of the best lessons involved RFI and high voltage...

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kingtal0n
Posts: 175
Joined: Mon May 23, 2005 2:42 pm
Car: 240sx
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Re: Megasquirt tuning sr20det

Postby kingtal0n » Tue Dec 06, 2016 9:18 pm

if its a stock sr20 350-380rwhp just use a power FC, ebay all the time for $350-$450

the ms ecu is going to give you a fight, foolin around with one for months when you could just plug in and go in a couple hours done.


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