muythaibxr

vref is for the TPS, so if you're not using that on the MS, or the stock ecu still supplies this to the tps, you don't need it, If the stock ECU still controls the BAC, and the AFM still turns on the fuel pump, you don't need either of those pins wired either. The Air temp sensor should not be considered optional, as air temperature is part of the ideal gas equation that's used to calculate the amount of fuel to inject.... meaning higher temperature = less dense = less fuel. Pin 28 is +12v for the megasquirt.

I personally do not know where the ignition circuitry is on the stock ECU... but could probably figure it out given an hour or two, and a multi-tester (and a stock ECU of course).

Ken

RyoFC3S

iTrader: (1)

Any suggestions then? It seems like my only real option now is to get another ECU and re-wire it like slpin's and see if that works. I don't know what else I can do.

Bleh.

-Andrew

muythaibxr

I can take apart one of the ECUs we have that we're ripping the connector off of, and try to figure out where that circuitry is, and what could go wrong with it...

But I probably won't have time until sometime next week.

Ken

RyoFC3S

iTrader: (1)

That would be awesome.

Also, I just noticed something. I don't know how significant it is... My ECU is an N370, but the ECU slpin gave me is an N374. Is that okay?

***EDIT*** I just did some searching about the N370vs.N374 swap. It seems that everyone says it should "swap without any problem" but there are numerous threads where people report problems with the swap. Here's what a couple people have said after doing the swap:

"ran great when I bought it, 2 weeks later I drop it in my car and it acts like its running on one rotor"

"everything plugs right in but i'm not sure why exactly that the Jspec ECU was making my engine run like crap."

"I swapped in a Jspec motor in my 90 FC and I got 3 N374 ECU that are in great shape and tested good, but when all 3 ecu's are plugged in, motor does not fire."

Sounds familiar...

Apparently, buying this:

http://www.mts.net/~chipsale/chipsforsale88-91rx-7.htm

...fixes the problem.

Any thoughts?

-Andrew

RyoFC3S

iTrader: (1)

Also, does anyone know how much an N370 ECU usually goes for? Trying to see if I can afford it...

RyoFC3S

iTrader: (1)

Bump, for last 2 posts. This is urgent...

muythaibxr

I don't know the answers to the last 2 posts...

RyoFC3S

iTrader: (1)

Okay.

I talked to a buddy of mine about all this for a couple hours. He came up with a good solution, which we're going to try tomorrow.

I'll let you know how it turns out.

Thanks again for all the help!

slpin

iTrader: (9)

you are looking in the wrong areas
why are you doubting my wiring when it was running properly when it was in mine.
the problem is in your harness - or maybe a bad pin connector?

the megasquirt only have direct control over 4 injectors - everything else, it reads and shares with stock ecu. thats why the emop would work properly too.

RyoFC3S

iTrader: (1)

Slpin, it was running properly when you had it, it IS NOT running properly now. It's my job to eliminate all possible causes. Everything has been checked. I can say with 95% confidence that the problem is that the N374 ECU (which is used only to control ignition) is fried. I am doing a test today and tomorrow which will make me 100% certain.

I'm not saying its your fault. I just want to fix it.

-Andrew

RyoFC3S

iTrader: (1)

Okay, did the check, and now I have the Megasquirt running and fully operational (with spark). Now I can finally start tuning the damned thing! Turns out slpin's modified stock ECU (the N374) was in fact fried (yes, i'm positive).

The setup I have now is a little simpler. I cut the wires that ran into the N374 ECU and tapped them into my factory wiring harness (before my stock N370 ECU). I also put a switch in the power source that runs to the Megasquirt unit so I can turn it on and off at my command (if I want to run on the factory ECU between tuning sessions).

Thanks again for everyone's help; this has been a great learning experience.

-Andrew

muythaibxr

Good to hear it's worked out finally.

Sorry I couldn't be of more help myself, I've never run in that piggyback configuration.

Ken

RyoFC3S

iTrader: (1)

The car is running very crappy. I'm sure its just because its not tuned correctly.

1. I was wondering if I did this correctly:



I read here in this board that I need to "set 0v to 10:1 and 5v to 20:1".. Did I do it right? Is it that simple? Is there something I need to change in the settings.ini besides changing:

#unset Innovate0_5"
to
# set Innovate0_5"

2. When I hold the pedal to the floor (to clear flooding) I believe it is still firing my injectors. The green LED (marked 'INJ') on the MS unit continues to blink. The indicator on the main screen does say 'FLOOD CLEAR' when the pedal is to the floor... Its having trouble starting now after a few starts (smells flooded). Do you think it is actually working correctly (not firing injectors at WOT cranking like stock) or its just adding MORE fuel when I do WOT?

3. What should the MAP signal typically read between 1000-2000rpm? I'm trying to make sure the sensor is working correctly.

4. This should all work and run fine without the stock AFM right? Right now all I have is a cone filter on the intake inlet for my turbo...

Thanks... hope that made sense.

RyoFC3S

iTrader: (1)

5. Is there an easier or more efficient way to tune the car? All i'm doing right now is changing the values in the VE tables until it 'feels better' then checking the A:F ratio. I've read in some other threads people mentioning things about 'Autotuning' and 'A:F Target Tables' - what's that all about?

6. How exactly does the barometric correction work? I live in Denver (5280ft. altitude) in the summer and winter, but go to school down in Los Angeles (sea level) during the spring and fall... I would love it if I wouldn't have to re-tune the car for either altitude.

Thanks guys.

renns

1.) Looks OK. Be sure to 'unset' the narrow band O2. Also, be sure to change to sensor type to 'Wide Band' in the EGO Control page.

2.) Not sure what code in your box, but if the flood clear light is on, I would expect both injectors to cease firing.

3.) In the garage, while modulating throttle from 1k to 2k and back, 30-50 kPa or so would be typical.

4.) How are you running your fuel pump without the stock AFM? Don't leave it wired to run when the key is on, or you run the risk of pumping fuel into the fire in the event of an accident. I ran with the stock AFM in place, but did remove for some brief testing. Others stated that ignition timing was directly affected by AFM signal, but I couldn't verify that, although my testing was limited.

5.) Read the tuning documentation first, then tune via the tuning screen while watching the AFR. Try to hold steady load/rpm combinations. Once you've done a few points, you can rough in the neighbouring points by reference pretty easily. It's all documented well in the manual. If you are sticking with dual table, it'll be more complicated up at the top end where the secondaries come on line. You'll be surprised how much of your driving can be done on primaries only when you run then up to 80% or so duty cycle. Again, I'd strongly suggest switching to a more recent code version that has staged injection, and tune with one VE table, but that's for you to decide.

6.) MS takes a baro reading on startup. You should be OK so long as you aren't driving from sea level to 5k in one go. Some have reported minor tuning changes required, but it shouldn't be anything drastic over that altitude range. If you do plan to do some drives over wide altitude ranges, then you may want to look at adding a second map sensor and enabling the continuous baro correction option.

RyoFC3S

iTrader: (1)

I was just outside (in the garage, outside air temp is about 32°F) cranking on it (couldn't get it to start.. think plugs might be fouled). At WOT, it was reading 80 kPa. At 0% throttle, it was reading about 72 kPa. Does that sound right?

The fuel pump seems to work exactly as it did when I had the AFM plugged in (bone stock setup)... It only turns on when cranking/running.

Okay, I will read the documentation. Is it a big ordeal/time consuming to switch it from my current setup to staged injection?

Well, the only transition between LA and Denver will be a 1 day road trip. Its about a 15 hour drive, with several stops for gas. Is that ok? If not, is it difficult to do the dual MAP sensor setup?

Thanks for the input.

renns

Seems reasonable, but I've never paid much attention to cranking map values. What does the map sensor read prior to cranking? If it's near 100 kPa and you're near sea level it's likely working fine.

Do the air and coolant temps match with the engine cold? Are they consistent with outside air temp?

Maybe that's been hacked in the harness/adapter already.

For someone familiar with the process it takes a few minutes to re-flash the code and set up MegaTune to match. There will undoubtedly be some re-tuning neede, but it sounds like you're at that point already. If you have a running setup, you may want to just drive it around a bit to ensure everything else is working, and then look at code upgrades.

Don't both with the continuous baro correction for now. Bring a laptop along when you do the first trip, and you can tweak if needed.

RyoFC3S

iTrader: (1)

It's at about 80 kPa when the car is off. According to MS's website, thats about right (it's accurate within 4 to 5 kPa). The barometric pressure here at Denver is about 81-84 kPa.

I do not have the air temp sensor hooked up currently. Is that a big problem?

The coolant temp is consistant with outside air temp.

That's all for now. I'm sure i'll have more questions tomorrow. I'm a good way through reading the "Tuning Your MegaSquirt" page on the website.

muythaibxr

In my opinion, it would be better to hook up the air temp sensor, as that provides a significant portion of the Ideal Gas equation's input for calculating the amount of fuel to go into your engine.

If you just left it unhooked, and didn't ground it, or put a resistor in its place, it'll fluctuate wildly, causing some weird problems.

Ken

RyoFC3S

iTrader: (1)

I see... right now its not wired at all (just a wire that runs out of the MS and ends--connected to nothing). I do think Slpin had it hooked up when he was running it in his car.... That may explain the roughness.

Where do you guys recommend I install it on the FC? I was planning on tapping it into my throttle body, where the 2nd set of throttle plates used to be.

renns

You need to find out if the MS board has been modified to use the stock Mazda air temp sensor. If so, just use the stock unit in the stock location to start. I found better hot-starts by moving it from the dynamic chamber to the plastic throttle body elbow, so you may want to consider that as an alternative. You definitely need that sensor wired up to operate MS properly.

jm93rx7

iTrader: (7)

dont mean to jack your thread but ive been following this and talk about some awsome response time and support.

RyoFC3S

iTrader: (1)

It hasn't been modified to use the stock sensor. As I mentioned before, slpin was using the GM air temp sensor on his setup, and he gave it to me to install on mine. Thanks for the help.

Hell yeah, that's why I love this forum.