MS1 random cut out while cruising

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12-11-2013, 09:22 AM

#21

duffbuster243

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Quote:

Originally Posted by kero

I, too, have the same issue.

MS1 v3 DIY built myself following the original thread.

I am getting dropouts around 3.5k RPM, so basically highway cruising.

I was able to follow the instructions pretty well to build the MS board as the picture tutorial was great. I tried to read the schematic but I am not 100% sure as I do not know symbols for everything. I used my mad MSPaint skills to add on to DIY's mod photo to show how I would solder in this 2nd opto circuit.

Can anyone confirm that this is correct?

Looks good, Just remove the original 2 resistors (Red Lines) that go from IAC1A to 5v and js8. I build my circuit on one of these: Dual General-Purpose IC PC Board : PC Boards | RadioShack.com and mounted it in the case.

12-11-2013, 01:01 PM

#22

kero

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Is there a different optoisolator I could use that I could source from Radioshack or Fry's? I tried searching 4N25 on their sites, but nothing came up

12-11-2013, 03:08 PM

#23

mellowout

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Quote:

Originally Posted by kero

Is there a different optoisolator I could use that I could source from Radioshack or Fry's? I tried searching 4N25 on their sites, but nothing came up

I think there is a 4n25 already on the ms3.0 board. Not sure if you could use it or not.

12-11-2013, 03:11 PM

#24

duffbuster243

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Quote:

Originally Posted by mellowout

I think there is a 4n25 already on the ms3.0 board. Not sure if you could use it or not.

the 4n25 on the ms board is used already for the primary input from the CAS. what you are esentually doing with this mod is duplicating that circuit for the sencondary input from the CAS. Digikey is fairly quick with their orders, I never looks elsewhere for the 4n25.

12-11-2013, 07:34 PM

#25

kero

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Quote:

Originally Posted by duffbuster243

Is there enough room to mount one of those? (I'm using the stock DIY case)

That seems like a neat way to do it

edit:

Parts list of what I just ordered

Attached Thumbnails

MS1 random cut out while cruising-jdwfe64.png

Last edited by kero; 12-11-2013 at 08:30 PM.

12-12-2013, 12:28 PM

#26

240_to_miata

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My MS has been changed so much over the years I gave up on my sloppy proto area. I just recently used that radio shack board in an external enclosure and just popped the necessary wires out of my MS enclosure to use for VCCS Sucks, but it was the easiest way.

12-12-2013, 12:35 PM

#27

duffbuster243

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Quote:

Originally Posted by kero

Is there enough room to mount one of those? (I'm using the stock DIY case)

That seems like a neat way to do it

Mine fit fine in the stock case. I cut the wafer in half though as you only need 6 slots of it for the 4n25.

12-12-2013, 09:24 PM

#28

kero

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Quote:

Originally Posted by duffbuster243

Mine fit fine in the stock case. I cut the wafer in half though as you only need 6 slots of it for the 4n25.

How did you mount it? screws? doube sided tape?

12-13-2013, 09:10 AM

#29

duffbuster243

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Quote:

Originally Posted by kero

How did you mount it? screws? doube sided tape?

On the back side of the board using one of the leftover holes on the heatsink, using one bolt and a little bit of hot glue to keep it from vibrating around.

12-14-2013, 06:07 PM

#30

mellowout

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Wired mine in the proto area using kero's picture. just took it for a (short) drive down the road. Too soon to report no problems, but it runs, which is good.

12-14-2013, 06:17 PM

#31

240_to_miata

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Nice. I will do mine this winter. I moved to a new shop last night. Driving on the highway @ 3400 for 20 minutes in 20*f weather it happened about 4 times.

12-14-2013, 06:55 PM

#32

kero

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Quote:

Originally Posted by mellowout

Wired mine in the proto area using kero's picture. just took it for a (short) drive down the road. Too soon to report no problems, but it runs, which is good.

Sweet. My optoisolator should be here Monday, hopefully I can do mine on Tuesday.

12-18-2013, 08:59 PM

#33

kero

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I just installed my circuit. Still had the same issue occur on the highway. Could my igniter just be taking a ****?

12-19-2013, 06:58 PM

#34

mellowout

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I've noticed that I'm still getting the misfire as well. I took a log and haven't seen an rpm spike but still had the stutter, albeit seemingly less often. I'll post my log up soon.

12-19-2013, 09:38 PM

#35

kero

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Quote:

Originally Posted by mellowout

I've noticed that I'm still getting the misfire as well. I took a log and haven't seen an rpm spike but still had the stutter, albeit seemingly less often. I'll post my log up soon.

Mine still shows in logs. I've read somewhere that a failing ignitor can cause this. Do you have a spare to test? I don't have another to try. I'm kinda dumbfounded