Megasquirt Install 2G wiring question

[TealTalon]

I'm megasquirting my 2g. This will be the third DSM this MS ECU has been in. The first 2G. I have no question on the actual installation of the device I have that all covered. What I am trying to figure out, and here is where I need some input, is whether or not I should remove the entire stock engine harness and install my complete ready to go MS ECU wiring harness I have.

The engine is out of the car for a 6 bolt swap (yay for 170,000 mile 7bolts). I am taking this opportunity to clean some things up in the engine bay. I already have a completed engine harness for a MS all loomed up from the last car it was in. It would be really easy to just toss that in, and wire up the 12v and grounds and go. The harness is nice and small. All the injector wiring etc, fits down below the fuel rail.

What I don't know is what exactly will not work after removing the stock 2G engine harness from the car. From searching I think I have discovered the wiper motor is part of the stock harness. The alternator apparently is controlled by the ecu as well. The speedometer probably won't work, and that is what prompted me to post this. Is it going to be too much of a hassle to fix what is broken by removing this harness?


The car is a street car/toy. The only creature comfort I don't care to retain is the cruise control. Everything else stays. AC is mandatory, I live in Florida.

I need some input here to help make the decision, but after typing this out I am already leaning towards the stock harness and a patch harness to the stock ECU.

 

[Ajax]

I know for a fact cruise control will not work. Bc that an issue for mine but I just spliced or cut some of my original harness wires. Also tach and speedo. Is your Ms setup for fan control? Otherwise that will not work either. Those are just a few things I found out thru mine. If it was me I would keep the original harness in, what if you want to put the MS in a fourth car later?

 

[TealTalon]

Your profile says you have a NT. Isn't the NT and turbo engine harness different?

You can add turn signals to the list of things that don't work without the engine harness, and I don't think the fuel pump came on either.

I think I have already made up my mind to go back to the stock harness.

 

[VelocitàPaola]

Your profile says you have a NT. Isn't the NT and turbo engine harness different?

You can add turn signals to the list of things that don't work without the engine harness, and I don't think the fuel pump came on either.

I think I have already made up my mind to go back to the stock harness.

The 420A and 4G63 harnesses are different, but a lot of the chassis wiring is the same. The gauges are pretty much the same, for instance, except for the 4G63's boost and oil pressure gauges.

Turn signals and hazard lights should work just fine without the stock ECU (or any connections to it).

Megasquirt is supposed to control the fuel pump, and you'll need to connect the A/C compressor clutch relay to a switch. You could also leave it always connected, but that would place undue load on the engine while cranking and at high RPM's.

 

[TealTalon]

I have wired everything in using the stock 2g harness. Everything is great, except one bank of injectors is not firing. Its not the wiring it's the ECU. I hooked up my Stimulator or whatever it's called. Pin 34 and 35 are not firing. The LED on the tester for that injector bank doesn't light and the other one does. I get spark on all four when it's in the car. It's reading RPM.

The question is, could this be a software/tune issue or do I need to start checking the ECU circuits?

My Engine constants are set the same way as Page 10 on this pdf http://www.megasquirtpr.com/downloads/How to MegaSquirt your 4G63 powered DSM.pdf

Except the PWM current limit % is set to 100.

 

[TealTalon]

Nevermind, I think I have a bad U4 chip. Basically in checking steps 1 and 2 are fine, step 3 below fails with no signal out of U4 on pin 5. It is receiving signal on pin 2 and 4, and sending out a signal on pin 7. Pin 5 is dead.


1. The CPU sends out signal to the FET driver on pins #21 (INJ1) and pin #22 (INJ2), near the L2 inductor. Recall that the pins are numbered starting with #1 at the corner with the dot, an are numbered counterclockwise from there. Check these on the LED tester, by putting the positive end of the tester against the pin, and be sure they flash.
2. The FET driver receives the CPU signals on Pin#2 (INJ1) and Pin#4 (INJ2), on the side of U4 closest to the CPU. Check these on the LED tester and be sure they flash.
3. The FET drivers sends out signals on Pin #5 (INJ2) and #7 (INJ1), on the side of U4 closest to the DB37 connector. Check these on the LED tester and be sure they flash. Note that the driver inverts the signal, so the flashing may look a bit different, but it should still flash at the same frequency.
4. The signals arrive at Pin #1 of the FETs (Q1 & Q5) on the heat sink, and are fed out to the stim LEDs through pin #2. Both of these should flash with the LED tester.

 

[v8killer]

Hi i am thinking of putting the megasquirt 2 in my car could you tell me does the speedo work with the factory computer unhooked ? i'm really tired of my 95 eprom ecu tuning issues !

 

[TealTalon]

I'll let you know when it runs...

 

[TealTalon]

I need some ideas here. I cannot get this thing to start. I have spark on all four. I replaced the bad chip and now have fuel on all four. Pulled the plugs and they are all wet. It pops a bit here and there, just will not start.

I found an old tune that I know works and have the loaded in that ECU. Firing order on the coils is 4123. Tried swapping the plugs to oposite coils. Engine timing is dead on. Tested the ECU with my JimStim and it's all working. Engine compression was tested at 150 on all 4.

 

[turboglenn]

My factory ECU is GONE, and the haltech USE TO run through the factory harness until wires started dieing from the stock harness in the bay.. SO since then i've been running wires from the haltech straight to thier respective locations on the engine.... YOu can keep eveyrhitn in your car functional with a stand alone, you just have to be carefull to only strip out the ires you took the palce of with megasquirt.. I sitll have factory tach, gauges, cruise, and everything.. it is a practice in patience to say the least if you want to retain all the OEM gauges and goodies (Like i did )

 

[v8killer]

My factory ECU is GONE, and the haltech USE TO run through the factory harness until wires started dieing from the stock harness in the bay.. SO since then i've been running wires from the haltech straight to thier respective locations on the engine.... YOu can keep eveyrhitn in your car functional with a stand alone, you just have to be carefull to only strip out the ires you took the palce of with megasquirt.. I sitll have factory tach, gauges, cruise, and everything.. it is a practice in patience to say the least if you want to retain all the OEM gauges and goodies (Like i did )

is this with the factory ecu removed from the car ?

 

[TealTalon]

I seem to be talking to myself here, but I think it's helping.

Is it possible the wiring shown here http://www.dsmtuners.com/forums/tuning-engine-management/305704-megasquirt-wiring-2nd-gen.html

is not correct for the injectors?

That posts shows:

32--------Injector 1-----------------------01
33--------Injector 2-----------------------14
34--------Injector 3-----------------------02
35--------Injector 4-----------------------15

Wouldn't that have injector 1 and 2 firing at the same time and 3 and 4 firing at the same time? Pin 32 and 33 are the same wire using the DIYautotune harness, and 34 and 35 are the same wire.

Would the correct wiring be this?

MS pin# stock ECU pin#
32--------Injector 1-----------------------01 Bank 1
33--------Injector 4-----------------------15 Bank 1
34--------Injector 2-----------------------14 Bank 2
35--------Injector 3-----------------------02 Bank 2

 

[blazinglaser_90]

I have mine firing 1&2 and 3&4 at the same time also. From many of convo's with DIY and Symtech the injector firing order doesn't really matter it seems mine ran the same with 1-2 and 1-3 and 1-4 together so i just let it 12, 34 and so far this works great at 32 psi and 9000 rpms

if your getting spark, fuel and compression the only thing i could think of is possiably the 2gs have a higher dwell requirement on their power transistor and your maybe not getting hot enough spark? just guess here, or i had my fuel set so high once it made the plugs wet like that

just trying to add to the convo

 

[TealTalon]

Any input is welcome at this point. 3 weeks of trying to get a motor to run that has run before on the same ECU is making me crazy.

I think I will mess with the wiring for the injectors and maybe bump the dwell time a bit tonight, I will also check the fuel settings, but this tune I am running has run the same engine well enough to drive down the higway before. The only difference is EVO injectors instead of 550's. I did adjust the required fuel setting, but based it off 560's. Should I base it off a higher flow number for the EVO injectors? I think they flow closer to 580 cc's correct? I didn't think it was significant enough to keep the car from running, but it's another thing to check I suppose.

 

[blazinglaser_90]

are you using inline resistors with the evo injectors? I saw one time where the evo injectors have such better response than 1g, 2g or any other injectors that on a dsmlink type setup u had to decrease the injector opening time. So it might be worth messing around with the injector opening time and if your not using the inline resistors it might be worth playing with the PWM of the injectors but i figure your using inline resistors since your splicing into factory wiring

you dont happen to have a set of 440's to test and just reduce the req_fuel time for 440's and give it a try do ya?

 

[TealTalon]

are you using inline resistors with the evo injectors? I saw one time where the evo injectors have such better response than 1g, 2g or any other injectors that on a dsmlink type setup u had to decrease the injector opening time. So it might be worth messing around with the injector opening time and if your not using the inline resistors it might be worth playing with the PWM of the injectors but i figure your using inline resistors since your splicing into factory wiring

you dont happen to have a set of 440's to test and just reduce the req_fuel time for 440's and give it a try do ya?

I have some 450's and the 550's that I used before. I am using the inline resistors. It may be a good idea to try the 550's that are known to have worked in the past as well. Thanks for the ideas.

 

[jrohner]

is this with the factory ecu removed from the car ?

I think that's what GONE means.

 

[blazinglaser_90]

yea for sure i would try limiting it out, you know the 550's work so give them a whirl and if that doesn'te work go from there. I found the dwell time to be a big issue with my car i had to take it from 3.8ms to 4.6 ms to get it to stop blowing out spark at 36 psi. Also i dunno how much it would matter but you said the tune was for 550's and a 1g.....2g's have a higher base fuel pressure so i mean that would be a bit more fuel on top of those 580's too ....unless u have an adjustable or had your fuel pressure other than factory 1g settings before

 

[TealTalon]

yea for sure i would try limiting it out, you know the 550's work so give them a whirl and if that doesn'te work go from there. I found the dwell time to be a big issue with my car i had to take it from 3.8ms to 4.6 ms to get it to stop blowing out spark at 36 psi. Also i dunno how much it would matter but you said the tune was for 550's and a 1g.....2g's have a higher base fuel pressure so i mean that would be a bit more fuel on top of those 580's too ....unless u have an adjustable or had your fuel pressure other than factory 1g settings before

Hmmm...my dwell settings during cranking is 5.0ms 3.6 running. I would think that would be enough spark to get the car to start. I'll eliminate the fuel injector issues and go from there. I am using the 2g stock regulator for now. I have an adjustable just not installed yet. I could alwyas put the 1g FPR on there too.

 

[turboglenn]

is this with the factory ecu removed from the car ?

yes, it's in a bucket in my room of parts

Hmmm...my dwell settings during cranking is 5.0ms 3.6 running. I would think that would be enough spark to get the car to start. I'll eliminate the fuel injector issues and go from there. I am using the 2g stock regulator for now. I have an adjustable just not installed yet. I could alwyas put the 1g FPR on there too.

Also, coils should be paired to 1&4 and 2&3... in a few years DSM switched wich coil wires are wich at the ignitor to ECU connection... If it just pops and sputters but nevere starts, take the plug wires off 2 & 3 and place them on the 1 & 4 plugs, then take the original 1&4 wires and put them on plugs 2 and 3, baqsically this is what the "cas inversion" in DSMlink takes care of. it was changed at least 3 times in the course of 90 - 99 (the other thing you can do is take the 2 wires that trigger the ignitor and swap them if that's easier to get to than your wires or if your wires are already running out of length

tey it, you'd be surprised how many times i've ran into this when some one calls me to troubleshoot qa stand alone install.

 

[TealTalon]

yes, it's in a bucket in my room of parts


Also, coils should be paired to 1&4 and 2&3... in a few years DSM switched wich coil wires are wich at the ignitor to ECU connection... If it just pops and sputters but nevere starts, take the plug wires off 2 & 3 and place them on the 1 & 4 plugs, then take the original 1&4 wires and put them on plugs 2 and 3, baqsically this is what the "cas inversion" in DSMlink takes care of. it was changed at least 3 times in the course of 90 - 99 (the other thing you can do is take the 2 wires that trigger the ignitor and swap them if that's easier to get to than your wires or if your wires are already running out of length

tey it, you'd be surprised how many times i've ran into this when some one calls me to troubleshoot qa stand alone install.

Swapping the plug wires to check for coil firing order issues was one of the first things I tried. Also swapping the two CAS signal wires fed to the ECU in case I had tach and crank signals swapped.

I'm still baffled on how a car can run properly firing injectors 12 and 34 together in batches instead of 14 + 23. It works obviously as was stated previously, it jsut doesn't seem correct.

 

[TealTalon]

Finally, it runs.

After swapping in the 550's and fighting the fuel rail leaking last nght I gave up for the night.

Tonight I fixed the leaky rail with a new o-ring on one injector. Messed around a bit with a fresh startup tune and decided to leave the injector wiring alone. Grabbed a new laptop and loaded up the high resolution spark firmware. Still not running. Pissed off I went inside and watched tv for a bit and had a beer.

It hit me.

I had swapped plug wires previously, but that was before I had found the bad chip on the MS1 board not firing one injector bank. I am pretty sure thats what made it finally kick over tonight. Swapping the firing order. Thanks to all for the input. After looking at a problem for so long you start to go nutty, and the ideas here really helped out.

Thanks guys!

 

[blazinglaser_90]

glad to hear it runs for ya! The reason u can run any injector order as long as #1 is on bank 1 is b/c no matter what the intake valve is open for only a partial time during the injection process and for the other part the fuel just puddles on the intake valve any ways. I've also seen them paired 1, 3 on bank one and 2, 4 were on bank 2. I've also seen some install write ups that just had them in order, 1,2 on bank one, and 3,4 on bank two. I don't think it matters as long as injector 1 is on bank one output. I would like to mess with it some more to see which one gives better throttle response b/c you would think that it would be the two cylinders that open one after another intake valve wise. I am doing a megasquirt now for another 1g so maybe i'll do some investigation on that and let you know how stuff works out!

congrats again good to see another car running the squirt!

 

[TealTalon]

So far the stock tach does not work. Can I jsut feed the CAS signals to the stock ECU following the 2G 6bolt swap wiring for a CAS? The MS has a tach output can I feed that into the stock ECU to make it work? The only search result is using an aftermarket tach adapter. I think I jsut don't know how the stock tach gets it's signal. Is it a seperate input from the PT or does it work off the Cam and Crank signals? What PIN on the stock ECU is it? i don't see one on the VFAQ 2g ecu pinouts.

The fans both come on and stay on as soon as the car is started. Is this because I have not attached a coolant temp signal to the stock ECU? (edit: yes it is. Fed the GM coolant temp wire into the ECU)

edit: I guess it's just pin 89 crank position sensor for the tach.

 

[blazinglaser_90]

on the power transistor there is a white wiring coming off it . You can run that to the wire inside the dash where the plugs go into the factory gauge cluster and your in business