12a bridgeport ms2 NA tune
 

Hello,

After a very long time, I am finally trying to start my engine. I am looking to get a base tune to start with.

My set up is
12a bridge
ITB 48 ida style
900cc injectors per rotor
Racing beat road race headers
Only running fuel
Ms2/extra

After I populate the settings for req fuel I get 4.7 which I though was extremely small. I changed it to 10 but still no start. A base tune would be very helpful, if anyone has one. Thanks

Req'd fuel of 10 with the VE tables on my website should start the engine after you add 20% to the VE table.

Cranking PW should be around 13 mS.

You'll need to run alpha-N. The MAP signal will be too ambiguous for speed density.

This assumes that you are getting RPM while cranking, injectors are firing, fuel pressure is correct.

Aaron, I've been following your write up. I'll do that and report back. Also, this morning I found out I plugged the trailing coil to the leading ignitor and vice versa. I spliced in the zener diode on the negative coil and jumped xg1 to spr4 for grounding. I think the spikes were resetting my ecu because it would randomly go off line then come back on after cranking or sometimes during cranking.

One question, in the window that you input the req fuel. I put 1200 cc disp, 900cc injectors and so on. I put rotary since the option is available and not 4 stroke like your write up and then it says number of cylinder/rotor so I put 2 and the number of squirting I put 1. Are these correct settings?

Since you are using the ECU fuel only with no staging, the rotary/piston setting doesn't matter, nor does the number of rotors. You could set it to 4 cylinder if you want. Injectors are batch firing.

I believe, and you'd have to check the documentation to confirm, but in all but the newer MS3 firmwares you need to double the CC on a rotary engine to get a valid automatic Req'Fuel calculation. Basically with your setup, you will need a Req'Fuel of between 8 and 10 mS. Otherwise the scale of the VE table is going to be off and you might find yourself hitting max VE but still needing more fuel.

Aaron, thanks. I did what you said and now i am battling no rpm issue. I connect it with the stimulation and i will turn the rpm potentiometer and you can see in tunerstudio that the rpm will blip to 300 then go back to 0 like it lost connection(The jumper for D2 was done for the ms to work and removed in the car). In the car it was also not getting rpm.
A couple questions that might help me. I jumpered xg1 to spr4 and then spr4 from the relay box ground, correct? Also, last time before this time that i tried to turn it on, i had mistakenly plugged the leading cable for the igniter to the trailing and the trailing to the leading, would this have cause something to break in the MS? To make sure i am not going crazy, per the wiring diagram, the rpm signal comes of the negative coil thru the yellow green wire and it connects to the igniter closest to the alternator which is the trailing one, correct? thanks for the help

I'm really not at all familiar with the relay board. However looking at the schematics the board doesn't really have anything to do with it. Basically a passthrough. Your coil negative gets connected to pin 15 on the terminal block and that is a straight passthrough to the DB37 pin 24.

I'm not sure why you are jumpering XG1 to SPR4 and then SPR4 to ground on the relay board. It's a very roundabout way to ground XG1. It would also mean that you don't get RPM on the stimulator unless the relay board is involved.

On the Megasquirt side, you need to jumper as follows:
-TachSelect to OptoIn
-XG1 to XG2
-OptoOut to Tsel

Your tach input/spark input then connects to the negative side of the leading coil. You may need to put a resistor in series with it (5K springs to mind) to avoid noise.

Reversing leading and trailing will not have fried anything. Can't see how.

Aaron, thanks for the response.
Now that you say that my tach input should come from the negative post of the leading coil i have it coming from the trailing coil because the 12a wiring diagram shows the rpm signal coming from the trailing coil, which i found strange, but i followed what the schematic said. The Yellow green wire is connected to the trailing neg post and it goes out to tach in the wiring schematic. Should i swap the yellow green wire to the leading coil and then swap the igniter connector to the leading igniter as well since the yellow green is the wire i have slated for rpm? Also, to check my sanity, the trailing igniter is the one closest to the alternator, correct?

The stimulator, i am inclined to believe that my rpm potentiometer might be faulty so i am not going to trust it.
https://cimg0.ibsrv.net/gimg/www.rx7...1a08e8890f.jpg

Trailing and leading should produce the same tach pulse, so either coil will work. I have personally always just pulled from the leading coil. Partly because in some early 1st gens the trailing coil was cut under some conditions such as decal by the "ECU".

Sorry, don't know which ignitor is which. It's been a long time since I've seen a stock 1st gen and I don't have any of my manuals handy. The FSM should have a diagram however.

thanks. I am still having rpm issues. It sees 12V all the way into the MS. But tuner studio shows 12 rpms while cranking, which i know is not right. I have set it up per the assembly manual for neg coil with C30 and C12 and D2 using the reversed zener diode. Do you have any suggestion on what to check? I am at my wits end trying to figure out what is going on.

Yes ,trailing igniter is the one closest to the alternator

thanks for the confirmation

So i finally got rpm. Aaron, it seems like after i loaded your tune, the ignition must have changed from fuel only. I still have some spikes, but when i put the resistance i get 0 rpm. It might be too high of a resistance, i also tried the Zener diode in line with the band closer to the coil but again i get 0 rpm when i splice that in. I only get good rpm without any resistor or diode. Now as you might see form my other post is trying to start. I dont think its fuel, it seems to be timing. If you have some pointers, it would be appreciated.

Yes, my map is set up for a 2nd gen CAS and 2nd gen coils. If you load the whole map it will reset the ignition to those settings. All you are probably interested in are the fuel related tables so you can just export them and then import them directly to your map.

If you are getting RPM without the resistor, leave the resistor off. Make sure XG1 and XG2 are jumped. Really the optical trigger circuit is very simple and once the 'Squirt is configured for the dizzy, the only changes you may have to make are farting with a series resistor.

Thanks, I'll play with it

Thanks, I'll play with it

I have no problems running a bridge port on speed-density. Rotaries work well in this regard because the intake is always pulling, it's not like, say, a 4 cylinder where each intake port only sees vacuum 1/3rd of the time, so if you gang them together the airflow gets lost to the other ports rather than going to the MAP sensor. (That said, I want to run ITBs on a four cylinder just to see if I can prove a theory I have, that speed-density would work on a four if you only pulled from TWO cylinders opposite each other, say cylinders 2 and 3...)

I do have a restrictor in my MAP hose, but that is a legacy from when I used to run MS1 base code, it can be done in software in MS2/Extra. I think. I know you can do it with the MS3Pro's firmware and I've being playing with nothing but that over the past year or so.

One thing I found is that I could not run MS2/Extra in fuel-only in "rotary mode"! There is a bug in the firmware. Running in "rotary mode" made the computer see double RPM. At 1300rpm, I was seeing 2600rpm. Needless to say, the engine was running INCREDIBLY rich with the double-fueling. Thank MSD that it was able to run at all. I had to go back and set it up as a 2616cc four cylinder (just like the old days) and all was well and I could get to tuning.

Here's my latest .msq to give you an idea of where I'm at. It's a 13B with MFR sized bridge ports and, allegedly, 1000cc RC injectors (primary location), but I have my doubts a bit. I never did any kind of experiments to check what the deadtimes actually are, that isn't as easy to do with a bridge port as it is with a soft-cammed piston engine. (And WOW is it easy to get it nailed on a soft cammed piston engine). Reported duty cycles are close to what they were when I was running 680cc injectors, although I did have the deadtime nailed for those, and there's a curiosity in the way MS reports duty cycle where it includes deadtime, so it is possible to go past 100% "reported" duty cycle and still get more fueling. (I've seen fueling increase up to 120% reported duty cycle with the 680s... mostly because I stopped there and went to the 1000s!)

Thanks, I'll try this tune and maybe running in rotary mode might be the issue. I'll change it. Since your is bridgeport even if it's a 13b it should start even if it's a bit rich.
One question, on the fuel map, the fuel load, should that be 0 to 100? When I loaded mine it was from 30 to 250 but I changed it to 100 max. Am I missing something there and is what I did wrong?

Atmospheric here is 95kpa, I have my top bin set to that for ease of tuning. WOT is the top row and everything else is drivability.

Do you know why tunerstudio does not let me put in 10k for the max rpm. It says the max is 9k. Do you know why or how to change it?

So this is the latest.
Could not run Speed density, the map barely moved so i switched it to alpha-N.
Also, for some reason running it in four stroke mode, the rpm would only get up to like 230 rpm, which from the way the engine was spinning it sounded a lot faster. Switching to rotary mode i think it doubled the rpm which seemed to be more in line with how fast the engine was spinning. It sounded close to turning on, it would backfire and sounded like it wanted to go. I am assuming now its fuel and not timing. I still have tach noise, which i am not sure how to get rid of it, i tried the noise filter in TS sand nothing. Also i put a 2k resistor and it improved but still jumped, then 3.5k and it still jumped. Then went to 4.5k and lost signal so i am kinda lost on how to get rid of the noise. Any suggestion?
Attached is the log file of an attempt in the beginning and the injectors unplugged to deflood.

What are your input settings? Can you post an MSQ?

Also, you should be running on the leading coil. 12As trigger the engine computer off of the trailing because the engine will run just fine if the trailing ignition fails, but will barely run at all if the leading does. So this way the engine will not run with half of a functioning ignition system. (Pre-81 rotaries triggered off of the leading, because the trailing was shut off sometimes for emissions reasons, keep the thermal reactor burning)

I was playing with the fuel table to see what worked and what didnt.
Take a look and let me know.
thanks

I also have the trigger masking on and it helped with the spikes a bit. Also, I am not sure why but no.matter how I change my fuel table the pulse with still goes all the way up to like 7.8ms.

If the engine speed is lower than cranking speed, it will ignore all fuel calculations and go off of the cranking pulsewidth map.

It should be set to about 300rpm if it is configurable. I forget if it is configurable in MS2, it isn;'t on MS1 and it is on MS3.