ae71 4age corolla on MS122-C fuel only coil neg rpm noisy

[slideways]

Hey everyone, in short im a mechanic and building my personal '83 ae71 toyota corolla missle car.. the car runs but gets a noisy rpm reading which usually occurs above approximitely 4k rpm. Running ms1 fuel only setup with rpm reading from the coil negative post on my single bosch coil. 4age 16v bigport engine with factory distributor and bosch ignitor. I dont have the laptop so i currently dont have any datalogs... i have a dyno to tune on and the car bucks hard above 4k and the only thing wrong is that noisy rpm.. everything else is spot on. Im so close! Do i need a resistor inline of the rpm signal? If so exactly where? Thanks in advance everyone

[dontz125]

Not sure what mods you have to the MS board, perhaps try this: Keep D1 (1N4001), but turn it around. Remove / jump out D2, add 1k resistor from D2 position to +12v. This sort of circuit has been tried by several users with the MicroSquirt unit and coil-negative triggering, and apparently gives a VERY clean signal. If you've already jumped out D1 and have a Zener D2, replace the zener with a 1N4001 pointing the same way, and add the resistor between D2 and C30.

[slideways]

I have the ms1 pre assembled by diyautotune, and i also used their harness, again what would the cleanest signal for coil neg triggering be? Thanks in advance! I have the ms1 pcb 2.2 part number ms122-c

[dontz125]

Sorry, I misread your initial post.

Flip D5, jump D8, add a 1k resistor from the D8 jumper to the banded end of D12, 13, or 15 (NOT D14), whichever is easiest.

[slideways]

Exactly what resistor do i need? 1k ohm but what wattage? Thanks

[dontz125]

P = E x E / R = 14 x 14 / 1000 = 196 mW. Go with a 1/4W.

[slideways]

You're the man! Going to buy one now and i'll report back later this week with my results, thanks again!

[slideways]

So my D8 already has what looks to be a short dark brown resistor? And D5 has a black one.. so i flip d5 but what should i do with whats already in d8? Jump of of that? Or remove that, jumper it, and go off that? Also exactly which side of each should i go to, thanks

[slideways]

Here is D5, i just flip the direction of this correct?


Here is D8, should i remove whats there and jumper it and tap the resistor off that? Or can i tap off whats already there? If so which side?

[dontz125]

D5 - correct.
D8 - you could leave the diode there and solder on a jumper, but it's better practice to remove the unused part. If you leave the diode in place, it doesn't matter to which side you attach the resistor because the jumper bypasses the diode.

[slideways]

Doing it now! You are a livesaver thank you again man

[slideways]

So i flipped D5, removed D8 and added a jumper, and ran the 1k ohm 1/4 watt resistor from the D8 jumper to D13.

Now i get no RPM signal at all when cranking, before the car ran.

???

[dontz125]

Banded end?

[slideways]

The computer connects to my laptop and everything else still reads fine, just now i have no rpm signal at all.

[slideways]

Banded end?

Banded end of what?

[dontz125]

Did you run the 1k resistor from the jumped-out D8 to the banded end of D13?

[slideways]

Did you run the 1k resistor from the jumped-out D8 to the banded end of D13?

yep, spun d5 around, removed d8 and jumped, then ran 1k ohm 1/4wt resistor from d8 to banded side of d13.

[dontz125]

Ahhhhh ... Crap. Jump out R10 - sorry.

[slideways]

So I also jumper R10? Leave D5 and D8 how i have them currently?

[dontz125]

Yes.