To start off with let me tell everyone that I am not extremely apt to the jargon of car tuning and I am learning as I go here so be kind.

I have read the complete faq and tried just pluggin those numbers into my MS and hooking her up to see how it runs. It did not and I have since restarted so I am going to try and go step by step with you people helping me along the way.

So let us assume at this point the least I want to do is get my car up and running.

Here is some info about my setup.

Car Body: 1983 Rx7
Engine: Came out of a 1991 RX7 Turbo (Automatic...Im not sure if this matters)
Megasquirt: Megasquirt V3.0

I have setup Megatune 2.25 with the "MegaSquirtnSpark Extra" extensions.

If my only purpose at this point is to get the car started and idling what do i need to setup first?

 

well you'll need fuel and spark tables assuming all wiring was done correctly.

And you'll probably want to reduce the cranking pulse widths a bit from the ones in the FAQ since those were for an NA

Also, you didn't say why it wouldn't run... were you getting fuel? spark? did rpms show in megatune?

start by posting an msq, along with a datalog, and the firmware version

 

Thanks for the quick response.

I have set up with the FAQ setup currently and I changed the pulse width as you suggested.

I guess here is my current problem more specifically. After i plug in the Megasquirt with the Stimulator and to the computer, I open up megatune and i open my msq which has all the settings (to the best of my knowledge) that were specified in the FAQ. It asks if I want to send & burn the values into the controller....I select yes...everything looks fine for a second and then the fuel pump light turns off and the rpms go to zero and show no activity.

I am not sure how to upload a file yet.

 

oh, that's expected behavior...

 

Attached are the msq and spark table foudn on this website.

I also included the generated fuel table I got from the program.

I am not extremely clear as to why the fuel pump and rps would show no activity and that would still be ok...will it change when i hook the car up or is the programmin preventing it from showing those things. If there is a simple explanation I would appreciate it...if it is highly complicated I am sure my dad would appreciate and then help me understand it.

Thanks...

 

the main reason you lose rpms when hooked to the stim is that the stim doesn't output a signal that looks like the wheel inside your CAS.

There are actually 2 wheels inside the CAS, 1 with 2 teeth, and 1 with 24 teeth. The 24 tooth wheel is used by the megasquirt to help calculate timing, and the teeth on the 2 tooth wheel are used to "reset" the count on the 24 tooth wheel, making the wheel appear to the MS to be a 12+1 wheel.

You don't see rpms anymore on the stim after using these settings b/c there is only a signal going into the MS from the pin that the 24 tooth wheel will be hooked to, and there's no "reset the count" signal coming in on the second VR sensor input.

So it's expected that you won't see rpms on the stim if the MS is configured correctly for an rx7.

 

Ok that makes sense...so does the lack of a rpm count also explain the loss of fuelpump activity or is that a different explanation? Oh and also did my settings look correct to you?

 

I didn't have a chance to load your settings.

The fuel pump is supposed to turn off when the engine isn't turning. So yes, the fuel pump turning off makes sense.

 

Ok the engine is cranking and I am getting some sputtering and some "trying to start " behavior. I am posting a datalog with this post and hopefully that will shed some light on the behavior.

During some troubleshooting though, we were checking the timing of the engine and noticed that the timing light was lighting up with the cas in erratic positions. The timing mark on the crank pully is only visible during the times when the engine sounds like it is trying to start running correctly. I am assuming that this is part of the problem but as you can probably tell from my vernacular...I am not very mechanically inclined. My role in this troubleshooting is limited to programming, consulting you fine people, and tweaking the settings accordingly. So in other words be kind when explaining anythign to me...lol.

 

looking at your settings, I see the following things wrong with wheel decoder settings:

1) 2nd trigger active edge should be "rising" not "falling (like IRQ)"
2) 2nd trigger and missing teeth should be no missing
3) Trigger angle should be 65 degrees (if you're using the standard CAS stabbing procedure)
4) If you're running a turbo, your injectors are probably pretty large, set req_fuel lower, try around 7.9-8.5
5) Are you really using a narrowband O2 sensor?
6) mSec per step is very low, try something like 150-200
7) Set cranking rpm to 400
8) You have AFR tables turned on, turn them off if you're using a narrowband. I HIGHLY recommend getting a wideband before doing anything other than idling with a turbo. It will make tuning a lot easier... You can tune for a specific AFR, and you can make sure you don't go too far away from that AFR. Tuning on boost is a lot safer with a wideband since you know when you're going too lean.
9) Your VE table only goes to 100 kPa, there is nothing there for on boost.
10) Same thing for your spark table
11) and your split table
12) You have outputs 1 and 2 turned on, but you've got a turbo engine, they don't need to be on

A lot of these things won't cause you not to start, but once you're started could cause major problems with a turbo engine.

Numbers 1, 2, and 3 above could cause you not to start, and could cause the weird cranking behavior.

Not trying to be mean or anything, but I don't want to see you blow the engine. IF you boost with some of these settings, the engine is going to blow...

Also, I recommend doing some heavy reading over at www.megasquirt.info and www.msefi.com in the tuning sections as there are a LOT of good resources there.

 

Well actually, I believe we just received a wideband 02 sensor today or yesterday that I was unaware of. So hopefully that will be installed promptly. I am making the changes you mentioned to the file as I write this so those will be taken care of.

I understand there is always dange of malfunction but as long as I am only trying to get the car to start and then idle I shoudl not have to worry about the boost scenarios yet correct? I am trying to take it slow but I personally am only available to oversee this project on the weekends because it is my younger brothers car and my father and him are doing most of the real work on it. I will make sure they know the danger of running these settings under boost. I appreciate all your help and your sound advice. not a word of it is being wasted so whatever you can spare I am there.

Thanks again hopefully an update tomorrow as well.

 

Would these still be true if we have a modified CAS, 24 with 2 teeth removed 180 degrees apart?

He also wanted me to ask if he has the CAS wired up correctly.
The colored wiring diagrams that is posted, along with the diagram that came with the harness shows that bothe CAS wires are terminated at each end. Somewhere , in one of the threads he read he remembers that only the MS end needed to be connected, and not the CAS end because of something called ground loop.

This is how he did it;
The leads going to the 24 tooth pick-up is one red wire and one white wire. The leads going to the 2 tooth pick-up is one green wire and one white/black. The shielded white wire from the MS is connected to the red CAS wire. The white and white/black wires are wired to ground on the engine. The green CAS wire was left connected to the old engine harness. He thinks that this is all wrong and would like some detail explanation on his mistakes. along with the best way to wire the CAS to prevent EMI.

I feel like I am overworking muythaibxr but I really do appreciate all the help. Once I have everything figured out I will probably try and type up a Dummie's Guide to Megasquirt so you guys won't have to put up with too many guys liek myself. :-D

 

with 2 teeth removed, you want second trigger turned completely off.

The wire he's thinking about that is only connected at one end is attached to the shielding around the CAS wire, and isn't one of the CAS wires itself.

If you cut two teeth out of the CAS, then the only wires that should be connected are the red and white wires... the red wire on the CAS should eventually connect to the MS tach pin, and the white wire should eventually connect to a ground on the MS.