ive been running megasquirt for over a year now, fuel only. ive been mostly working on the fuel side. so far fuel is working good. i can boost to 15psi with no detonation. stock computer controlling timing.
i built a second megasquirt 2.2 using a single lm circuit with a modded crank sensor a year ago. i couldn't get a tach signal. then just the other day i decided to recheck my connections. building the vr circuit just looks like a mess. i was trying to get errors board but was unable at the time. so i built it on a radioshack generic breadboard. then i relized that i connected to the wrong pin 6 on u4. for some reason i counted the pins like you would on a v6 engine. so it was the wrong pin.
finally connected everything on the car...what do you know, it runs!
cold starts and accel warmup has always been an issue since i dont have any of it hooked up and bac valve isnt working. since the weather is always on the warm side, its something i could live with since i dont drive the 7 often.
several things ive noticed. the stock tach doesnt work. i'll have to consult the service manual to see how its wired up. timing seems to be off. i'm unable to get any data logs. i think im using the wrong version of ms log viewer. looks like i'll be busy for a while.

 

the stock tach won't work unless trailing is working... so verify operation of trailing ignition.

If the timing is off, set "fixed angle" to -5, and then use a timing light to adjust the CAS, then set "Fixed angle" back to -10.

 

Not trying to undermine you, but I would instead suggest marking the pulley with 20BTDC, get the car running set the fixed angle to 20, rev the car past 4000rpm and adjust the timing that way. There will be less error

 

I disagree... maybe verify the timing that way after setting it using the method I explain, but I do not suggest revving up the engine, even under light load before you set the timing using the light.

It's unlikely you'll hurt anything, but better to be safe than sorry.

Also, how would it be any more accurate? The only difference is that there is less time between the trigger and the spark, but as long as engine speed is stable, that doesn't matter, and then you have to be sure you mark it in the correct place too, introducing human error.

Ken

 

Perhaps it's old-fashioned, but a pulley with timing marks beyond the stock mark is quite valuable IMO. That way you can verify that spark events are occurring accurately at points beyond that single idle point. I also like to verify that timing is advancing as expected when fixed timing is turned off. This sort of testing only takes a few minutes, and provides some assurance that the spark timing and advance are functioning properly over a wide rpm range. Without those simple tests, it's a matter of blindly trusting that the coding guru's didn't break something with the latest release!

 

I agree, and I put those marks on my own pulleys when I'm trying to verify something, but again, trusting those marks adds the element of human error. I prefer to do the initial timing setup with the marks that are already on the wheel to make sure the only error there can be (Aside from code errors of course) are setup errors.

After setting the timing using the method I described, then by all means verify it using any method you can come up with, including marking the pulley if you really want to.

My point is only for initial setup, there's no reason to marking up the wheel and revving the engine to 4000 rpms. I like to keep things simple, especially when someone is new to the megasquirt.

Ken

 

trailing isnt working? i never did check w/ the spark tester on all four wires. i'll have to do that after i get back from vacation. should all three leds flash? i did recall the last one not lighting up, i forget which # it was.

 

the middle led should flash when running at lower revs, the other two should just get dimmer as the revs climb.

But yeah, if your tach isn't working, trailing isn't working most likely.

 

ok, just to clarify. on the oem pulley there are two marks, one yellow the other red. yellow is tdc, and red is 10degrees after tdc? or is it 5? setting timing to -5 on megatune. with a basic timing light the pointer should be on whih mark at idle?red right? or white? i know timinhg is suppose to be about 10degrees btdc at idle.
i think i went stupid after my vacation

 

the stock mark is definitely 5atdc on the leading ...

 

w/ the timing light it looks like its about 10 degress before tdc. cas is maxed retard so im thinking im offa tooth. i'll try restabing it in. i need a timing light w/advance.

 

you don't need a timing light with advance, you just need to set the MS for -5, and then use the timing light to turn the CAS until timing lines up with the yellow mark.

 

so im setting base timing at 0 degrees. after that i set it back to -10, and megasquirt will now handle timing. sounds simple enough, i'll do that tomorrow after work. it did run better when i was retarding though. im definitely a tooth off.

 

What vintage is this engine, or more specifically the pulley? The reason I ask is that earlier engines had the leading mark at TDC rather than 5 ATDC.

 

What systems are driving the trailing coil off the V3 board?

 

the middle LED, and the right LED (looking at the MS from the front).

 

this is a s4 t2.

 

yeah, then the yellow mark is -5 degrees, or 5ATDC, so to set the timing correctly, the MS must be set to -5 fixed angle and the CAS must be adjusted so that the yellow mark lines up properly with the timing pin when using the timing light. After this is done, the fixed angle can be set to -10.

 

ok. all leds light up. the middle one flashes when running. using the timing light connected to t1 wire, trailing is not firing. if the leds are on, can i assume that trailing selet and trailing timing is working? can i check on voltage at the led or something? i dont have a working scope at this time.

 

i wonder if the transistors are working.

 

question. LED 18, what is the voltage for the trailing select output? also what is the voltage for LED 19, trailing timing? withe the key on engine off, i get voltage reading about 2.5v. im assuming that all of these are squarewave. is there a way of manually triggering the base on the transistor.

 

I have a 13B-RE Cosmo engine (about 1992, I think). Is my mark at 5 ATDC or at TDC?

 

With the pullups installed properly, the voltage of the squarewave going to the ignitors is going to be +5v... but measuring with a multimeter won't show 5v.. it'll be rpm dependent.

 

No idea. Check the FSM to be sure.

 

interesting. i was working on the car and out of frustration i started hitting the trailing coils with a screw driver. for a couple of seconds i got spark! then i couldnt get it to spark again. i also noticed that the leading ignitor gets hot. not the coil but the ignitor. something is going on here. i think there are gremlins at work.