MS1 - hard/NO starts

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Matt Cramer
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Post by Matt Cramer » Wed Feb 06, 2013 6:54 am

It looks like you're getting a bunch of noise pulses. I would check the condition of the wiring, and maybe trying the false trigger protection.
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Post by Spoolin6er » Wed Feb 06, 2013 8:29 am

Matt Cramer wrote:It looks like you're getting a bunch of noise pulses. I would check the condition of the wiring, and maybe trying the false trigger protection.
Is there reason why I would be getting extra noise with the new wiring configuration? Do you mind explaining the reasoning behind having me switch from the "high to low" circuit to the "low to high"?

The false trigger protection can only b set to on or off in MS1 right? Or are there settings I'm missing some where?

The wiring in this car is pretty decent (much better than my older mx6), and I'm using the stock, shielded wiring. I checked the the resistance between MS BD connector and the wiring into the distributor and its < .4 omhs. Not really sure how else to check it.

I found a scope to borrow - hopefully I can figure out how to use it...

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Post by schmauster920 » Wed Feb 06, 2013 1:26 pm

Check the continuity of both wires, the shielded wire and the sensor wire. The sensor wire cracks with age and contacts the sensor wire. Thats what happens to our knock sensor sub harnesses over the years
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Post by Spoolin6er » Wed Feb 06, 2013 2:36 pm

*EDIT* - I see what you mean, I'll check when I get home..

Thanks

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Post by Spoolin6er » Wed Feb 06, 2013 10:18 pm

Checked to make sure the ground and signal wires had no continuity, and they don't. Should there have been anything showing up? Like some very high resistance that is internal to the CAS? I always hate checking for "no continuity" b/c its easy to not have a good connection to the wires you are checking and you would never know.

Anyway, decided to mod it back to a high to low circuit. Its back to the way it was, but maybe a little worse as far as miss fires under load. I originally thought they were caused by issues in my tune, but after looking at the tooth logger, the CAS signal is definitely my issue. Its much cleaner than the above screen captures, but its not right either. Its like its bad, but good enough for the false trigger prevention to figure it out (most of the time).

I wasn't able to get the scope today, but hopefully tomorrow... Do I tap into the optoIn and XG2 locations?

*EDIT* - was looking closer at the schematics for the hi-lo and lo-hi mods, and I realized when I switched to the lo-hi mod I didn't re-install c12. Although, the hi-lo mod shows using c12 and c30, and DiyAT suggests removing both here:
http://www.diyautotune.com/tech_article ... _240sx.htm

Got me thinking - should I mess with R12 or maybe add those caps? I've heard of people changing R12 to 1k for EDIS... but I don't know what they do, just a thought.

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Post by Matt Cramer » Thu Feb 07, 2013 9:56 am

It wouldn't hurt to try putting the cap back in; it's there for noise filtering.

To use an oscilloscope, you'd check TachSelect for the input and TSEL for the output signal.
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Post by Spoolin6er » Thu Feb 07, 2013 12:57 pm

Ah, well I'm no longer near my car, but I took a look at the input signal and the tooth log. The tooth log looked the same as usual, with what looks to me to be missed teeth more than false teeth. (constantly incorrect/varying positions of "long" pulses, and every once in a while a few shorter than normal pulses)

Here are some pics from the scope: (TachSelect to XG1)
https://lh4.googleusercontent.com/-Uz83 ... .39.26.jpg
https://lh4.googleusercontent.com/-tRYH ... .34.42.jpg
https://lh3.googleusercontent.com/-Gqcj ... .32.56.jpg

I think that last picture has some screen ghosting. The signal looks pretty clean at idle and constant rpm except for what seems like a consistent tooth with some noise while its high. When I rev the engine it goes pretty crazy (voltages seem to jump) I tried some type of auto mode, and it seemed to look better - but I don't know anything really about scopes...

I'll post a video shortly.

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Post by Spoolin6er » Thu Feb 07, 2013 1:50 pm


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Post by Spoolin6er » Fri Feb 08, 2013 10:08 am

comments? I don't really know what i'm looking at/for here.

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Post by nismoautoxr » Fri Feb 08, 2013 3:13 pm

thats not anything I recognize . If you have the time and voltage parameters on the scope adjusted correctly you should be getting a 0-5v square wave form which Idont see there .
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Post by Matt Cramer » Mon Feb 11, 2013 7:25 am

The signal actually looks pretty good to me. I'd investigate where the MS is grounded at this point.
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Post by Spoolin6er » Mon Feb 11, 2013 8:53 am

That's what I thought. I'm using the stock ECU grounds, so I don't know exactly where they're going. But there is a huge ground lug (to the body) next where the stock ECU was that I assume is where some of the ECU grounds go. Here is how I have it wired:

https://docs.google.com/file/d/0B1cQUbx ... sp=sharing

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Post by Spoolin6er » Tue Feb 12, 2013 7:37 am

is there a way to check for noise on the MS grounds while I have this scope?

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Post by Matt Cramer » Wed Feb 13, 2013 9:29 am

You can run the scope from a ground point on the MS to the negative terminal of the battery, and see what the voltage looks like.
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Post by maik21 » Wed Feb 27, 2013 1:22 pm

i used to see some sr20de distributors get dirty with oil inside it. when that happens with stock ecu, sometimes car revs gets erratic and hard to start. when car start , it dont work as supposed to be working.

i install one of this 24-2 disks from diyautotune but i dont use wasted spark. i only use 24 slits to have ignition in coil. car starts better than with oem ecm every time you turn key. car friend is only for drag so it is used 1 or 2 times per month. so it have a long time sitting in garage.

when i installed this little disk, distributor has some oil inside. so i cleaned it very well. maybe you have this problem to. ka distributors are similar to sr20de b13 sentra.

i use instructions for configuration from diyautotune. theres a install guide for nissan b13s, so maybe you need to take a look.

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Post by maik21 » Wed Feb 27, 2013 1:30 pm

you need to be sure optic sensor inside distributor is clean. if not, you need to try cleaning it.

tacho spikes too when i first put megasquirt in the car but it was because i take signal from -coil ant sent do tacho. i only put a resistor between tacho and -coil. this tacho is driven from oem ecu so i only put a variable resistor and find the right resistor for this configuration and it worked very fine from idle to 7800rpm.

i have other problem where tacho spikes and was from a bad coil dwell configuration. it spines at 5000 rpm and misfires to, but i get the good dwell configuration and the it work fine all the way without spikes in tacho and without misfires.

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Post by Spoolin6er » Fri Mar 01, 2013 1:37 pm

Sorry it took so long, ground scope video is up:
http://www.youtube.com/watch?v=-yL-2Zvj ... tube_gdata

It looks very similar to the CAS signal logs in that there is noise while accelerating the engine, but not while holding a constant rpm.

Thanks maik21 - the CAS is very clean inside. However, I haven't messed with the dwell settings much. Any idea how that could causes tach spikes? It sounds like your first problem was the actual tach in the dash, when I was referring to tach spikes, I meant rpm spikes seen in the MS logs. Looking at the tooth logger shows there is definitely something going on with the CAS signal or the decoder...

What are you guys using for dwell settings with the stock s14 KA24 coil?

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Post by nismoautoxr » Fri Mar 01, 2013 4:36 pm

3.5ms max and 6ms cranking and around 1ms spark duration was what I was running with no problem but I did not run single coil for long . 3 months on single and I switched to LS2 coils and the 12-1-12-1 wheel from DIY but with the same optical sensor and dizzy. I always had problems with starter kickback with the 4 slit wheel. That was eliminated by the 12-1 wheel from DIY. HIghly recomended.

Have you tried a known good dizzy for giggles?
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Post by Spoolin6er » Sat Mar 02, 2013 12:10 pm

3.5ms max and 6ms cranking and around 1ms spark duration was what I was running with no problem but I did not run single coil for long.
I'm 3.5ms running, 6.0ms cranking, and .2ms min discharge period (not even sure what that means)

No i haven't tried a known working dizzy (besides mine, since it was working before I installed MS). I don't know anyone that will let me take their dizzy and open it up to install my wheel. There's always the junk yard, but that doesn't really count for known working...

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Post by Spoolin6er » Tue Mar 05, 2013 11:25 am

Hey Matt, have you had a chance to look at the scope of the MS ground that you asked for?

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Post by Matt Cramer » Fri Mar 08, 2013 8:16 am

Took a look at it and that looks like a fair amount of ground offset. Where exactly is the MS grounded? In our experience, "good chassis ground" is often a contradiction in terms.
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Post by Spoolin6er » Fri Mar 08, 2013 11:16 am

I just made an adapter to the stock ECU wiring, so its grounded to the same place(s) as stock (there are quite a few ground wires). I assume most of them go to a ground lug with several wires that comes right off the engine harness and grounds to the body near the stock ECU location. It is on the side of the passenger foot well.

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Post by Matt Cramer » Mon Mar 11, 2013 10:58 am

It would be better if you grounded the MS to the engine block or cylinder head.
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Post by Spoolin6er » Mon Mar 11, 2013 1:42 pm

I'm pretty sure it is grounded there as well. I have like 6+ ground wires leaving the MS, and I'm pretty sure one of them comes off the engine harness and grounds to the head. I will check to be sure...

Is it possible to have too many ground locations? Should I ground to the engine only?

Thanks

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Post by Matt Cramer » Tue Mar 12, 2013 6:19 am

Using multiple separate ground locations can create ground loops. Use a single point.
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Post by Spoolin6er » Wed Mar 20, 2013 3:06 pm

Alright - this is really getting annoying!

I re-ran wires to the CAS with shielded wire and grounded the shield at the MS - no change.

[rant]I need to vent for a sec and say that I HATE Nissan for making all the wires in the distributor plug black, white, or b/w!! and the FSM is garbage, NO pinouts aside from the ECU![/rant]

I de-soldered all the grounds except the new CAS ground and shield, and the sensor ground. Then I ran two wires side by side to an OEM ground point on the head. - NO CHANGE.

The tooth log looks exactly the same. The missing tooth pulse seems to come at random intervals - some times only separated by a few teeth. :?

I'm about to give up and go with some other EMS

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Post by Matt Cramer » Thu Mar 21, 2013 5:57 am

Can you try using the VR conditioner input? It is a bit more sensitive and less likely to miss pulses.
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Post by Spoolin6er » Thu Mar 21, 2013 9:27 am

Interesting - is this going to effectively invert my square wave? ie trigger one tooth off?

Any specific instructions? Pots fully clockwise?

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Post by Spoolin6er » Thu Mar 21, 2013 2:36 pm

So i never drove the car after removing the extra grounds and replacing the CAS wiring, I just looked at the logs and saw that it had the same issues and called it.

Well, went to drive it today, and its MUCH worse! I haven't taken any new logs yet, but its crazy because it feels kinda like it did when you told me to switch between low-high/high-low. The car never misses when the engine isn't under load, but as soon as i load it (>25% throttle), it starts missing. What could possibly be causing interference only under load??

I'm so lost :(

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Post by Matt Cramer » Fri Mar 22, 2013 5:46 am

That's a good starting point, but you may need to adjust the trim pots, and you will definitely need to check the timing (the trigger angle may have changed). Can you get a data log of it breaking up?
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