Megasquirt 2 in parallel with factory ECU
10-13-12, 09:13 AM
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Megasquirt 2 in parallel with factory ECU
Afternoon all!
About a year ago i took my SC300 off the race and started my NA-t build. One of the biggest things going on now is fuel control. In the beginning i was running a SAFC and everything was fine till the stock computer finally realized there was a turbo strapped to it. So then I went with the GReddy EMU. Lets just say it needs better support from greddy tech department and there knowledge of usdm 2jzge motors. Now I going megasquirt.
From what i have researched from 5 mouths is there very easy to tune and understand. The only down side is there aren't many people who have installed them into the SC300 willing to give up how the installed it. Thus my question is this, if you have installed megasquirt in parallel with your factory ecu where did you ground all five grounds from the MS box, did you use the "Ne" for crack position/ tach signal, and finally are the wires for the injectors running from the factory ECU to the injectors just grounds?
Any and all information and input is welcome as this will be the first time i have ever built a ECU let a lone installed anything this hardcore.
About a year ago i took my SC300 off the race and started my NA-t build. One of the biggest things going on now is fuel control. In the beginning i was running a SAFC and everything was fine till the stock computer finally realized there was a turbo strapped to it. So then I went with the GReddy EMU. Lets just say it needs better support from greddy tech department and there knowledge of usdm 2jzge motors. Now I going megasquirt.
From what i have researched from 5 mouths is there very easy to tune and understand. The only down side is there aren't many people who have installed them into the SC300 willing to give up how the installed it. Thus my question is this, if you have installed megasquirt in parallel with your factory ecu where did you ground all five grounds from the MS box, did you use the "Ne" for crack position/ tach signal, and finally are the wires for the injectors running from the factory ECU to the injectors just grounds?
Any and all information and input is welcome as this will be the first time i have ever built a ECU let a lone installed anything this hardcore.
Last edited by Chef; 10-13-12 at 09:14 AM. Reason: miss spelling~
10-13-12, 01:54 PM
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I can see this ending up not ever running again......
OK, the wires from the ECU to the injectors are, ironically, the injector signal wires.
Tach signal comes from pin 4 on the igniter.
NE is a crank signal. G1 is your cam signal. There is a positive and negative for both of these.
Also, Megasquirt replaces your factory ECU (at least on every application ive ever seen it ran on anyway)
Why don't you just buy a PnP ECU for the GE? This seems like such a better idea than the headaches MS is going to give you. There's probably a reason why not many people run MS, or have given up trying to get it to work properly. Just my $.02
OK, the wires from the ECU to the injectors are, ironically, the injector signal wires.
Tach signal comes from pin 4 on the igniter.
NE is a crank signal. G1 is your cam signal. There is a positive and negative for both of these.
Also, Megasquirt replaces your factory ECU (at least on every application ive ever seen it ran on anyway)
Why don't you just buy a PnP ECU for the GE? This seems like such a better idea than the headaches MS is going to give you. There's probably a reason why not many people run MS, or have given up trying to get it to work properly. Just my $.02
10-13-12, 02:18 PM
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I highly recommend you PM shaodome on here as he is a master with the MS stuff and can easily point you in the right direction or contact me and I can get him to call you direct.
10-13-12, 08:40 PM
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Thank you for the help guys. I will get in to MS tomorrow morning early *** hell so i can triple check everything i do. I didnt want a PNP system because my best friends SC300 GTE just threw a piston up threw the hood of the car because the aem died. So it was even more important the it was made by me and if so installed by me.
10-14-12, 12:17 AM
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I can see this ending up not ever running again......
OK, the wires from the ECU to the injectors are, ironically, the injector signal wires.
Tach signal comes from pin 4 on the igniter.
NE is a crank signal. G1 is your cam signal. There is a positive and negative for both of these.
Also, Megasquirt replaces your factory ECU (at least on every application ive ever seen it ran on anyway)
Why don't you just buy a PnP ECU for the GE? This seems like such a better idea than the headaches MS is going to give you. There's probably a reason why not many people run MS, or have given up trying to get it to work properly. Just my $.02
OK, the wires from the ECU to the injectors are, ironically, the injector signal wires.
Tach signal comes from pin 4 on the igniter.
NE is a crank signal. G1 is your cam signal. There is a positive and negative for both of these.
Also, Megasquirt replaces your factory ECU (at least on every application ive ever seen it ran on anyway)
Why don't you just buy a PnP ECU for the GE? This seems like such a better idea than the headaches MS is going to give you. There's probably a reason why not many people run MS, or have given up trying to get it to work properly. Just my $.02
Also where did you ground the MS to? Instructions say to the engine block. This is the major thing thats holding me from starting the install is the grounding points and tach signal.
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10-14-12, 12:23 PM
#8
I honestly don't know where exactly to ground the ms, But I'd assume that the intake manifold would be fine. Also, I'm willing to bet that circuit NE is gonna give you your tach signal as well.
Honestly, I believe from what you have posted that you need to leave this stuff alone (the install) for at least a month and read and get a better understanding on how all this works, then report back to this thread with any other questions or maybe with the answers to what you've discovered to be right. Not trying to bash you and definitely not trying to discourage you as I think this could be cool, but I do feel you should be more familiar with what you're trying to do here or you'll have a lot of problems and frustrations. tweak didn't say he gave up or he had problems, he said there's probably a reason only a small group of people use MS and theres a reason people give up on getting it to try and work properly. The MS has the capability to work great, but only if you understand how fuel injection and FI electronics work. You sound like you need a better understanding.
To clear things up about your question for the injector to ecu wires, you're kinda right. what tweak calls signal wires are actually a pathway to a ground. an injector is basically just a solenoid. One side has switched power, the other side leads to the ecu where when called for fuel, gives it a quick pulse to ground.
Why are you using the stock ecu in conjunction with this? And why are'nt you using the existing power/grounds out of your existing harness?
Honestly, I believe from what you have posted that you need to leave this stuff alone (the install) for at least a month and read and get a better understanding on how all this works, then report back to this thread with any other questions or maybe with the answers to what you've discovered to be right. Not trying to bash you and definitely not trying to discourage you as I think this could be cool, but I do feel you should be more familiar with what you're trying to do here or you'll have a lot of problems and frustrations. tweak didn't say he gave up or he had problems, he said there's probably a reason only a small group of people use MS and theres a reason people give up on getting it to try and work properly. The MS has the capability to work great, but only if you understand how fuel injection and FI electronics work. You sound like you need a better understanding.
To clear things up about your question for the injector to ecu wires, you're kinda right. what tweak calls signal wires are actually a pathway to a ground. an injector is basically just a solenoid. One side has switched power, the other side leads to the ecu where when called for fuel, gives it a quick pulse to ground.
Why are you using the stock ecu in conjunction with this? And why are'nt you using the existing power/grounds out of your existing harness?
10-14-12, 03:06 PM
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Your right about one part i do need to do more research, but not on fuel injection. The reason i have so many stupid questions is how MS is worded per the instructions given by DIYautotune. the grounds coming from the MS unit are for the different controls within the MS like map sensor, ignition, injection, and etc. I myself would like to keep my automatic transmission in play. To do so the factory ecu and MAF have to stay in place for shift point/air flow conversion.
With other systems i've tried and installed my self this one presented a challenge unlike Greddy EMU, Apexi FC, and HKS FC IV. The MS does not use correction math to figured out what type of fuel injection is needed at an give point, its only what I the programer tell it it can do and when. Just like in my restaurant my line cooks can make any dish they damn well please but they follow what i say when i say and how. <--- ego trip, sorry lol. But in my opinion that's how fuel injection should work to and so far Ms is the only unit that I've seen to match what i need/ want it to do.
So back to your point of the grounds on the main ECU. The grounds on the MS are based on not having the stock ECU present at all. Meaning all sensors water, air maf, o2 are run on MS and the sensors you wire to it. I will be leaving all of the main sensor hooked to the main ECU and tapping each i need to get MS to control fuel only. The main ECU does a damn good job of controlling ignition at only 7psi and i dont plan to push any harder than that. With the grounding points already set for the preexisting sensors i shouldnt have ground MS to the same grounds as the ECU since all i'm doing is tapping in to the signal not taking the sensor. Ive been threw club na-t, supra owners club, supra freaks, and so on with little to no info on just fuel control with factory ecu. everyone wants to kill off the distributor, witch thats was the easiest part to do.
With other systems i've tried and installed my self this one presented a challenge unlike Greddy EMU, Apexi FC, and HKS FC IV. The MS does not use correction math to figured out what type of fuel injection is needed at an give point, its only what I the programer tell it it can do and when. Just like in my restaurant my line cooks can make any dish they damn well please but they follow what i say when i say and how. <--- ego trip, sorry lol. But in my opinion that's how fuel injection should work to and so far Ms is the only unit that I've seen to match what i need/ want it to do.
So back to your point of the grounds on the main ECU. The grounds on the MS are based on not having the stock ECU present at all. Meaning all sensors water, air maf, o2 are run on MS and the sensors you wire to it. I will be leaving all of the main sensor hooked to the main ECU and tapping each i need to get MS to control fuel only. The main ECU does a damn good job of controlling ignition at only 7psi and i dont plan to push any harder than that. With the grounding points already set for the preexisting sensors i shouldnt have ground MS to the same grounds as the ECU since all i'm doing is tapping in to the signal not taking the sensor. Ive been threw club na-t, supra owners club, supra freaks, and so on with little to no info on just fuel control with factory ecu. everyone wants to kill off the distributor, witch thats was the easiest part to do.
10-14-12, 05:15 PM
#10
Uh, the emu doesn't use fuel correction math? Iirc the map is at zero which is what your stock fueling is at, then you add/pull til the wideband says happy. I use one and it gives me control over fuel just fine. I use it on non vvti 1j (map based) and vvti 1j (maf based). I use the greddy pressure sensor to tune fuel based on relative pressure. I have had zero issues other than it having a queer 32bit OS comPatible only driver. I have bigger injectors, using the injector correction is gay. I use I/J1&2, scale my maps for both vacuum and pressure, and pull fuel until I don't need to. Very simple, very effective. It's not the way the the ms stuff is worded, if you had understood what I had explained about the injector "signal" wire as tweak calls it being the negative side then you would have had that nailed down. Essentially it sounds like you're replacing an emanage ultimate with a more complicated emanage ultimate in a sense just using the MS for fuel. So basically you're just looking for more fuel resolution than what you can get with an safc or safr?
Did you have the greddy pressure sensor and harness? What was the reason you're ditching the emanage?
Did you have the greddy pressure sensor and harness? What was the reason you're ditching the emanage?
Last edited by Vrank; 10-14-12 at 05:19 PM.
10-14-12, 05:38 PM
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Yes i got the map sensor, 3 plug harness and o2 harness from greddy. The reason im pulling it out is when i make my fuel corrections its the EMU doesnt change anything the ECU is doing. When i first got the EMU i had injectors plugged in to it. But when i made all the corrections under injector table it would run 10.0 A/F at 0% throttle @ 650RPM. Pulled injectors and left them on the stock computer. Ill tell the EMU i want to run 12.0 A/F at 85-100% throttle position from 5,000 - 6,500 RPM and ill get 10.3- 9.0 A/F 4,000- 6,500 RPM. I called and talked/emailed Greddy for 2 mouths straight and they could never figure out why it wouldnt make any changes to the tables.
10-14-12, 09:16 PM
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I have quite a few friends who run MS, and hate it. loses tunes like it's it's job, and the ECUs are VERY picky about the way circuits are ran.
As for grounding, I would assume you could use a factory ground circuit. Harness grounds on the block, there are 2, then one from engine to chassis, one to battery negative, and one from batt negative to chassis.
10-15-12, 05:26 AM
#13
Did you select 2jzge in the drop down menu? If so that wont work for your engine im pretty sure. And also, it sounds like you were trying to use the autotune feature. Did you have temp reading as celcius? It doesn't like it when you have temp reading in farenheit. Also, tuning by tps is sketchy. Just because you're at a certain throttle position doesn't mean the engine will always be under the same load.
10-15-12, 12:02 PM
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No GReddy and i made a Universal tune set up based on the 2jzge and rewrote it via email and zip files for the hot wire MAF. I can only say im use to tuning with throttle position because of the safc's i've had in DSM's.
At the moment im having a issues trying to get megasquirt to pick up throttle position sensor 5v reading. I dontknow if its because i grounded the sensor ground on the MS. So in a hour ill be cak in thee with my volt meter trying to source the voltage i need for the signal.
At the moment im having a issues trying to get megasquirt to pick up throttle position sensor 5v reading. I dontknow if its because i grounded the sensor ground on the MS. So in a hour ill be cak in thee with my volt meter trying to source the voltage i need for the signal.
10-15-12, 05:54 PM
#15
The fact that you confine yourself to tuning by throttle position based on using an safc on a dsm, and also that it took weeks of emails to figure out that you enter everything from the 2jzge and change the airflow signal to the appropriate hotwire maf input or flapper type to suit your car leads me to agree with the quote below.
Tuning by TPS is retarded. You're spending time and money trying to get away from the onfines of an safc to gain "full control", but fail to do the research and take the time to do things properly. I"m going with my original thoughts of saying you need at least another month researching fuel injection theory first, and then pouring through the MS functions second. If you read through all the greddy manuals, and then spent a few hours navigating the software I'm quite confident that you could have had your car working fine. There are parts of it that you just have to figure out for yourself like the autotune not like F* temp readings, the jumpers for the water temp not being right in the suggested configuration, and a couple other small things, but it comes with getting faniliar with what you are trying to use. The stuff you have attempted to use and are attempting to use ARE NOT SAFC'S, STOP TRYING TO USE THEM AS SUCH.
I'm sorry if this comes across harshly, it's not meant to, but there's no other way to put it. Either take the time to figure out how to do it right, or don't do it at all.
Tuning by TPS is retarded. You're spending time and money trying to get away from the onfines of an safc to gain "full control", but fail to do the research and take the time to do things properly. I"m going with my original thoughts of saying you need at least another month researching fuel injection theory first, and then pouring through the MS functions second. If you read through all the greddy manuals, and then spent a few hours navigating the software I'm quite confident that you could have had your car working fine. There are parts of it that you just have to figure out for yourself like the autotune not like F* temp readings, the jumpers for the water temp not being right in the suggested configuration, and a couple other small things, but it comes with getting faniliar with what you are trying to use. The stuff you have attempted to use and are attempting to use ARE NOT SAFC'S, STOP TRYING TO USE THEM AS SUCH.
I'm sorry if this comes across harshly, it's not meant to, but there's no other way to put it. Either take the time to figure out how to do it right, or don't do it at all.