OK, I'm a bit nervous about this, but from what I've read, I think I'm about ready.


I have:
streetport gsl-se engine in a 1979 SA.
full streetport racing beat exhaust
2nd gen ignition running off of msns-extra using 2nd gen CAS
I had a VDI intake but in bolting down my 2ndary fuel rail, I broke off a bolt in the threaded hole, so I am reduced to a regular 2nd gen intake. (total wakeup call, I was moving too fast and was being careless)
emissions removal.

The car was running ok with the stock gsl-se ecu and wiring, but I wanted to get down and dirty with it, because my mileage was horrible (like 8-10 miles a gallon) , and there were some wierd flat spots in the powerband (I'm assuming due to a messed up MAF)

Megasquirt is wired in. Every sensor is grounded to pin 19 except for the CAS which is grounded to pin 7. The wiring was simplified greatly by using an RS Motorsports harness, which was very easy to use. I followed the post by Renns a couple days ago for the ignition wiring for MSNS-Extra.

pin 25 goes to IGt-T
pin 27 goes to IGs-T
pin 29 goes to IGt-L

I modded my v3.0 board (self built of course) as Renns did here:
https://www.rx7club.com/megasquirt-forum-153/v3-0-ms-build-pics-534544/

I'm using the cut teeth method with the built-in VR sensor in the megasquirt board. Today I tested my CAS by spinning it by hand and got RPMs on megatune. I don't have a scope to test my ignition outputs... The CAS wires are twisted together and shielded with the braided shielding provided by RSMotorsports. I tested my temperature sensors and they work, my map works, my tps works. For TPS i'm using a regular s3-s4 tps on a s5 throttle body cam.

MS is priming my fuel pump properly.

Is there anything else I need to do before I try to start? Software (firmware is v029k or some such, from a couple weeks ago) is set up according to the FAQ as best I could.

Can I mess up anything expensive if there's a gross problem? Also, for my innovate wideband... is there anything special I need to do for this to work? I have wired it according to the specs, but I have heard rumors that megasquirt can fry the wideband controller some times.

Thanks for the FAQ, btw. This would have been impossible without it. That, along with Renns thread below on the v3 board.

 

Sounds good so far! There is a mod to the MS outputs. You have to put a resistor in series with each output. Chech the Inovate site for upgrade recommendations. I`ll try to find the link later today and post it.
Scoctt

 

Sounds like you've done a thorough job on the build and testing of your MS. Congrats! You are nearly ready to run. Just a couple things to check:

1.) The Innovate wideband should have a 470 ohm resistor fixed in series with the analog output wire that goes to the MS O2 input. I'm not clear on the exact issue, but Innovate says it's needed until they upgrade their hardware.

2.) Injector size/quantity/wiring? The stock S4 or S5 n/a injectors would be fine. Wire the primaries to bank1, and secondaries to bank2. A guy here recently popped his motor due to a mix of low and high impedance injectors. Be sure to check the impedance of all your injectors, and run series resistors (or configure and tune for Peak&Hold in Megasquirt) if low impedance.

3.) Stab the CAS, and set base timing. This could be done by pulling the leading plugs, grounding them to the block. Hook a timing light to rotor1 leading, crank, and adjust the CAS to get the leading timing mark on the pulley close to the mark. Final adjustment will be made once the engine is idling, so I wouldn't worry too much about it yet. It just needs to be in the ballpark to start properly. Also, make sure the fuel system is disabled (pull fuse, disconnect fuel pump, or disconnect injectors) when cranking, so you don't start a fire.

Do a final engine bay check. Check all fuel connections, and get a fire extinguisher handy, as fuel leaks are common at this point in a project. Throw in a base map (muy, are any posted in the FAQ yet?), and start the engine. Read through the tuning section on megasquirt.info, as it covers the remaining steps in detail, and is applicable to rotaries as well.

Once the engine is warm, and idling well, confirm the ignition timing stated by Megasquirt matches what you see with the timing light. Adjust the CAS as needed to get a perfect match. Re-check this a couple times before the first few tuning runs to be sure it's OK. Then you'll have some comfort that the numbers displayed on the laptop actually match what's happening in the car.

 

Thanks for the replies. My injectors all four of them, checked out at 13.8 ohms, which from what I understand is high impedance. They are stock 2nd gen injectors, red connectors from an 88.

I hadn't heard that about the resister on the innovate controller output. I'll get that connected up asap. I did turn my MS on with the wideband controller hooked up already... could I have fried it before even running it?

As far as setting base timing. I cut the teeth on the CAS by rotating my front pulley till it was on the leading timing mark, and cutting the tooth that is lined up on the pickup inside the CAS. I stabbed the CAS the stock way with the marks lined up on the shaft and gear, when the pulley was on the leading mark on the engine. I cut the other tooth opposite 180 from the first. The teeth ended up being the 2nd teeth counterclockwise from the 2 teeth on the 2 tooth wheel. Or maybe the 3rd teeth counterclockwise, I can't remember without looking at it.

 

here's what I would do if I were you:

Pull the CAS out... and find tooth # 3

Line that tooth up with the pickup on the inside of the CAS.

stab the CAS back in, keeping it lined up with tooth #3.

then you can use the normal 1,3 7,9 wheel decoder settings, and a 60 degree trigger angle...

Once you've done that restab and get it started, then you can use a timing light and fine-tune the timing.

 

do you mean the 3rd tooth from the 2 tooth wheel or 3rd tooth from my gap?

 

3rd tooth from the gap. The 2 toothed wheel is completely irrelevant when using the 12-1 scheme. The 24 tooth wheel with 2 teeth missing, each at 180 degrees, is equal to a 12-1 crank wheel because the CAS wheel spins at exactly 1/2 half crank speed. Each tooth on the 24 tooth wheel is 30 degrees of crank rotation apart.

-Mike

 

Just to clarify, you should have the e-shaft rotated so the leading timing mark is aligned when follow the above procedure. Whatever method you use does not replace verifying timing with a timing light. Errors in CAS alignment are multiplied by two in e-shaft degrees, so get that checked and set right away. There's comfort in knowing the advance angles displayed in MegaTune actually match what's happening on your engine!

 

OK, everything is ready to go to start the car, I got the TPS sorted out and calibrated, set up all my software, etc.

When I spin my CAS by hand I get RPMS, but cranking I don't get any. From what I understand this is a grounding issue, so tomorrow I will reground somewhere else and see if that fixes it. Right now I have the main ground strap from the battery bolted to the drivers side fender as stock, and from there it goes to the engine. At the fenderwall is where I have my ground going, right off the battery. I suppose I will move it to the engine, further from the battery.

A couple more things: I don't have a condenser hooked up at this time, because it looked like from the 2nd gen ignition diagrams it is just in parallel with the ignitors, and couldn't figure out how it would help - is this a big deal for some reason?

2nd: in my firmware I noticed a setting for inverted ignition output - do I want it inverted or normal? By default, inverted was selected. There's all kinds of screens like this in the Megatune software where stuff is different or not included in the FAQ. I just assume in these cases to leave them default. Is this correct?

Once I get RPMS I should be able to get a spark right? or is there something else i need to do?

One last thing: once I set up the firmware to do the spark outputs, I had some anomalies. One went away after I changed a bunch of other settings according to the FAQ, but it had me really worried for a while: The fuel pump was flashing on and off when I would set up LED 18 to spark output. Really strange. It went away once I changed some other spark settings. The LED's now all go on and stay on and only flash when I spin the CAS. Before I changed the settings in megatune, they reacted the way they were supposed to according to the test procedures: the LED close to the DB9 flashed with injector pulses, etc. Is this normal for msns-extra?

 

fuel pump flashing means you have a settings conflict... when you see that behavior, you can start hyperterminal, and turn on the MS, and see the error.

If you don't get rpms while cranking, you probably have noise issues... grounds can sometimes be the problem, but there are also other things that can cause it.

Spark should *not* be inverted... I'm sure that one of the screenshots I posted also has "normal" for the spark output.

What condenser are you talking about?

For spark... did you put in the pullup resistors? Other than that, if you're getting rpms, and you've hooked everything up right, you'll get spark.

The behavior of the LED's is normal... now that you're using them for spark, they won't do the same thing they used to.

 

Right, as I went through all the settings, the flashing fuel pump went away, so I figured it was some kind of error code.

What besides grounding can be the problem? I have a grounded shield around the twisted pair of wires going to the CAS. AFAIK that should be clean.

The condenser I'm talking about is external to the coils, wired in parallel to them, from coil power to ground. I noticed this in the 2nd gen ignition wiring diagram. Wired that way, the only purpose I can see it serving is for noise quenching.

As far as spark goes, I will test by spinning the CAS by hand tonight to see if I get a spark now that all my settings are good.

 

Are you getting a reset in MegaTune while cranking? If so, you've likely got your MS powered via a 12v supply that is hot during run, but not crank.

That test will work fine, but be sure the fuel pump and/or injectors are disabled, or you'll have a flooded engine in short order.

 

yeah, as usual, I assumed that you'd have connected power to the main relay, and not to a place that doens't have power during crank.

So definitely check that like renns says.

Assuming you have power during crank, then it's likely you have some noise issues keeping the megasquirt from syncing.

I've seen a few things cause it not to sync:
1) you have the VR wires backwards... in many cases this will prevent you from syncing, and in the cases where it doesn't, you can end up with other problems.
2) Bad grounds or the shielding isn't grounded well.
3) Starter motor is noisy... sometimes a new starter will cure this.
4) Diode in alternator is bad... I've seen this cause all kinds of problems, and not just while cranking.

It is easiest to check on what renns told you to check on, followed by the VR sensor wiring.

 

MS is definitely getting good power, I am not using any stock wiring, everything is fresh except what is under the dash. The relay / fuse block I have is wired all fresh, etc. Maybe it would help for me to snap some pictures of my setup.

Currently, the shielding is grounded to one of the MS grounds. I don't know if this is proper procedure, actually. would it be better for it to have its own ground maybe?

Should I run a ground strap to one of the starter terminals? Right now it's grounding through itself, only power from the battery is running to it.

I could also play with some condensers on different locations to quell noise perhaps. I think that's the only reason for the condenser on the stock 2nd gen ignition.

 

check that you have the VR wires the right way, that's very easy to check, and if it's wrong, it'll cause a lot of problems

 

OK- I have nice spark, just not during cranking. Still can't get RPMS during cranking. I moved the main MS ground all over the place: engine block, transmission, battery post, radiator, everywhere I could think of and it didn't help.

I also double checked the VR wires - they are correct according to the FAQ. I get RPMS all the way up to 5000 when spinning the CAS with my drill (2500 rpm drill), so that seems correct. The other thing I experimented with was the shielding. I regrounded that in a few different locations with it making no difference.

I tried disconnecting the alternator, however I haven't tried swapping starters yet. I will try this next.

The only thing I noticed in the settings that may affect me is there's something called "trailing edge or leading edge" and "IRQ style" in the wheel decoder settings, which is different from how the FAQ shows it. Now it seems split into a couple different options.

 

yeah, for you, you just want missing tooth with no second trigger since you are using just the missing tooth.

Having noise on crank really complicates starting, especially with the missing tooth decoder..

With the 2nd trigger, you can usually get sync even with some noise, but with the missing tooth, if there's so much noise that the MS isn't seeing a missing tooth, it'll never start.

I'd also recommend playing with the hysteresis potentiometer inside the MS. It's the one furthest from the heatsink.

 

Check your battery cables and engine ground strap. If you are getting electrical noise during cranking, then those are suspect. Many older cars end up with corrosion between the cable end terminals and the wire itself, causing eventual starting problems. Even a good jumper cable placed between the battery -ve and the engine might be worth trying for test purposes.

There are many 100's of users running the 'missing tooth' configuration on other non-rotary vehicles, so don't worry about your choice in that regard. Do go through the setup of the VR pots as Ken mentioned. There are detailed adjustment procedures in the manual here: http://www.megasquirt.info/ms2/vradjust.htm

Ken, does the embedded code not still calculate rpm, even if it never finds a missing tooth? As this guy is seeing no rpm indication during cranking, that might be a good clue in determining the source of the problem.

 

When I installed the rebuild, I installed a brand new OEM groundstrap and battery cable, so I will double check the connection at the starter and try swapping in a spare starter.

I will also check the pots and adjust them.

 

yeah I wasn't saying that missing tooth was a bad choice... just that you have to REALLY make sure you're not getting noise for it to work right. I use 12-1 on my corolla without problems. (After adjusting the hysteresis pot).

The embedded code does not calculate rpm until it syncs.

One method I use to see if I'm getting a noisy signal is the following:

1) disconnect the fuel pump power in the trunk
2) disconnect the power to the ignitors (leading and trailing).
3) find the "stim for wheel" option, and turn it on.
4) crank the engine

If you get rpms while doing that, but not with stim for wheel off, then you have a noise problem. Just don't forget to turn stim for wheel back off.

Since you said you get rpms while spinning the CAS by hand, I'd say that you definitely have a noise issue.

Also, how did you wire up the VR sensor conditioner jumpers inside the MS?

 

I jumpered those according to the FAQ. I didn't get a chance to do anything last night but I will hit it hard this weekend.

 

I know that feeling, haven't been able to work on ms2/extra since the weekend because I've been busy getting peoples' plug - n - play units tested and packaged.

 

OK - Update: I'm getting RPM's on cranking, but no spark? seems wierd to me. IT must be a software setting somewhere.

The problem with getting RPMS during cranking it turns out I never turned the 2 pots on the MS board all the way counter clockwise. I went to adjust them, and started turning and they weren't clicking. I kept turning and turning and finally I did get them to click. Crank, and boom, I 've got RPMS. Now I'm getting spark by hand, and RPM's during crank, but no spark during crank. What could this be?

 

wait I think my trailing and leading outputs might be miswired. I need to go double and triple check those.

 

Oh yeah, I got it figured out! I followed Renns's diagram so religiously that I didn't use the common sense check. He constructed his V3 board to use IAC2B, IAC2A, and IAC1B pinouts in his picture, which correspond to pins 27, 29, and 31. However his wiring diagram uses pins 25, 27, and 29.

Having run a wire from pin 31 to my leading ignitor, and rewiring my pin 27 and 29 wires, and discarding the pin 25 wire, I now have spark! In fact when I tested it, my engine popped and wanted to run! So all I have to do now is set my base timing and finish all my looming and it should run.