Hey guys,

finally got time to plug in the ms and try it out... noticed i was not getting any spark.
checked the megatune display, and noticed i dont get any rpm value when cranking.

so my question is, the tach in MT should at least wiggle while cranking, right? (with plugs out, so probably 600rpm or so)

what should i check to see why my vr input is not working? ( i do not have a stim)

also, in the instructions it says to turn the pots for the vr circuit all the way counter clockwise-- but mine do not stop at any certain point...are they supposed to have a limit, or does this mean they are no good. and if they are supposed to be free spinning like that, then which way should they be facing?

also when i first tried the ms, i had it turned on with the B+G code while i was changing code variants, i noticed that my vb921s were kind of hot. pulled the plug, and loaded the msns-e code with no problem, and 921s have been fine since. also at that time i did not have the tach-vr jumpers installed.
could i somehow have harmed the vr circuit when this happened?

thanks,
pat

 

they will stop eventually, just keep turning. you have to turn a lot of times to get the Pots to stop.

If they're still turning, that's probably what's killing your tach signal.

 

like how many is a lot?
ive turned them maybe like 200 turns.... cant be that much room in there...

 

try turning with your fingernail, or listen for clicks.. they might not stop, but they click when you've gone too far.

 

They're either 10-turn or 20-turn pots. They won't stop at the end, just a faint click once per revolution when they're at the end.

 

yeah, i figured it out.
also figured out i had a jumper missing, hence no tach signal.
vb921s seemed to be having a pretty hard time driving the coils tho...they were getting really hot. tried copying all your settings from the ecu. didnt help.

then i fucked up and set the output to non-inverted.
fried the cpu.
project 20b-ms is definately cancelled. i just dont have any more time or money to spend on this. maybe in a few weeks i might be interested in buying an assembled board, including spark outputs. does anyone sell them on here?

edit: if its just the cpu, maybe i'll order another one, and see what i cna do with it. heres what happened...after i fried it, it would connect sometimes, but when it did it just showed all the sensors at funky places and they didnt change any. so i reloaded the code on the processor and it seemed to fix it. also i clipped all the wires for the 921s. then i went to the house, took a break, and tested the 921s, all of which were apparently still good. came back, resoldered the ignition stuff, same funky numbers again. tried reloading the code, but it would either get no response from the MS, or it would come back with "-wha" a couple times it let me start loading it, but then when it got to the end it would expect a boot completed message, and the MS wouldnt reply, so it would cancel it. also tried clipping the ground on the 921s, which i assume should have disabled them, with no effect.

sound like a fried cpu, or is it some problem with the serial controller?

note that right from the start it has always taken me a couple tries to get it to connect, so maybe smoking it just worsened an already bad situation. also once i accidentally shorted out one of the 921s, and for some reason that made it connect.

man i hate this thing
pat

 

well the 921's get hot when you're running too much dwell for the coils... they go into current-limit mode, and start getting really hot, and causing all kinds of EMI noise.

It sounds to me like you may have taken out the serial controller... I'd try replacing that and the cpu since they're both fairly cheap... you should be able to get DIYautotune to send you those and charge you accordingly.

 

I accidentally fried my CPU once. It sorta behaved as you described. I got another one from Al Grippo.

 

Al no longer sells just single cpus... you have to go to one of the distributors.

 

If you have access to a chip programmer, you can buy the processors and program them yourself as well. For most it's much easier to just purchase a replacement from one of the resellers. In the early days of Megasquirt there was even a kit being produced to allow diy programming of the raw processor.

 

Yeah, the "willette programmer"

I'm not sure you can still get those, although building one shouldn't be too hard.

 

new cpu didnt help

i'll try a new serial controller friday when i go back home (at school now)

 

man i had a nightmare with this crap. make sure your cas is gapped correctly.

 

ok, so i am assuming that on e way or another, i can fix my ms and get it online saturday. so assuming i do that, heres another question: for the brief time i had it working, it only fired about 1/3 of the time i thought it should, although it seemed that the timing was always right when it did fire. what should i check to try and fix this? i was thinking maybe just play around with the dwell settings. also i have the leds in there right now, that is correct for running 921s and stock coils (without stock ignitors), right?

thanks,
pat

 

ok, heres an update on my little pain in the *** project:

a new serial controller got my MS back online, and lowering the dwell settings to 2.2 for cranking and 1.8 for running cooled the vb921s down to a more moderate 'red hot' level instead if 'molten magma' like they were before. Unfortunately, now i have a new problem: about 90% of the time when i turn the key off and cut power to the MS, it wipes the firmware from the CPU. when i turn it back on, it connects to megatune, but the fuel pump cycles on and off, and i get the same bogus sensor readings everytime, which dont change.

if i reload the code, it will work fine until i turn it back off, then same thing again.
i have 2 cpus, does the same thing with both of them. oddly enough it also displays the same bogus sensor readins on both too.

i did get the 20b to fire up and run ok for a minute or so, so i'm hot to solve this problem so that next weekend i cna go home and get it back on the road!

anyway, I do have the MS here at school with me, along with most of my electrical tools, so if anyone can tell me what might be wrong, i'd appreciate it!

thanks,
pat

 

Fuel pump flashing doesn't mean that the firmware is wiped, it means your settings are conflicting somehow. Next time you get it to happen, use hyperterminal to connect to the MS... turn on the MS, and look at the error message.

 

wow that was easy. thanks.

now i have to wait a whole week before i can try it out. damn.

i had my coil a set to trigger at 0, and return at 1. apparently thats a no-no. is there anyway to use a negative trigger angle, or will i have to re-stab the cas?

my timing was correct with settings (0,1) (2,3) (4,5)

now i had to change it to (1,2) (3,4) (4,5). can i still get the same spark timing with these settings somehow?

 

you can't use a negative trigger angle, and trigger angles below 20 degrees are going to put you in next-cyl mode, which doesn't work with wheel decoder.

 

well i guess my roommate and i are gonna jump on the bikes and ride home after classes wednesday to see how she runs.

can somebody check and see how many teeth the bottom CAS gear has? (the actual gear that meshes with the eshaft) i dont have avy rx7 stuff up here and i want to figure out all my trigger settings before we go, since we will only have a couple hours to work on it.

thanks
pat