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> Zach's Carbs to Microsquirt conversion thread, 7/20/18 update
ConeDodger
post Feb 24 2017, 06:30 PM
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QUOTE(76-914 @ Feb 24 2017, 12:48 PM) *

QUOTE(McMark @ Feb 24 2017, 05:52 AM) *

Possibly EMI.

Great Amazing find, Mark. That is just insane! I'd have committed Harry Karry long before finding the problem. Curious; not even the presence of millivolts at the starter?
See Zach; that was a smart move. How many mechanics would have pursued that mystery with Mark's tenacity? Dedication, commitment and the desire for excellence come to mind. (IMG:style_emoticons/default/beerchug.gif)


Mark has a big brain. (IMG:style_emoticons/default/evilgrin.gif)

He told me that once when I asked him how he figured out some obscure thing on my car...
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jd74914
post Feb 24 2017, 07:46 PM
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QUOTE(Spoke @ Feb 24 2017, 06:58 PM) *

So put in a different starter and the VR sensor works fine? What is the VR sensor? Is that a power supply for the Megasquirt?

Variable reluctance sensor for engine position. (IMG:style_emoticons/default/smile.gif)

Glad you got the problem corrected. (IMG:style_emoticons/default/smile.gif)

QUOTE(Spoke @ Feb 24 2017, 06:58 PM) *

Since it seems the actual root cause has not been determined besides putting in a different starter, I'll take a guess that with the original starter in the circuit, there is some sort of instability causing oscillation wrt the impedance of the starter and the characteristic impedance of the power rails. Not all dc power supplies are stable over all load conditions.

I'm curious as to the root cause as well.

In general the MS DC-DC converter is of a pretty poor (not robust) design, as is the Microsquirt VR sensor hardware input filtering/processing. I literally could not get Microsquirt to reliably pick up a noisy VR crank sensor (worked fine on a number of other ECU's). The solution for the Microsquirt unit was to use a JBPerf conditioning board to pre-process the VR sensor and produce a square-wave output for the ECU.

http://jbperf.com/dual_VR/v2_1.html

VR sensors are passive to unless there is some EMI I wouldn't expect a lot of noise created by some voltage instability, but it would be interesting to see how the Microsquirt hardware reacts.

It would be interesting to have seen what the VR sensor was outputting via oscilloscope. Bet the signal was noisy.
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sixnotfour
post Feb 25 2017, 01:33 PM
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Son's smile says , my first car is almost ready for me (IMG:style_emoticons/default/driving.gif)
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VaccaRabite
post Feb 27 2017, 01:31 PM
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Sitting at work daydreaming about driving my car this spring.
Its been a long long LONG time since I have done that.
I'm excited.

Zach
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mepstein
post Feb 27 2017, 01:49 PM
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QUOTE(Vacca Rabite @ Feb 27 2017, 02:31 PM) *

Sitting at work daydreaming about driving my car this spring.
Its been a long long LONG time since I have done that.
I'm excited.

Zach

(IMG:style_emoticons/default/smilie_pokal.gif)
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McMark
post Mar 5 2017, 05:21 PM
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Turns out, as is so often the case, that there were two issues contributing to the same problem. After I posted above that I thought I had the whole thing solved, I came back the next day and the signal was wacky again. I didn't touch or change anything, it just didn't work anymore. After a bit more testing I found that the VR signal wires weren't being shielded correctly from EMI. So I added a jumper wire from the shielding to batt. neg. and everything cleared right up. Pulled the jumper, problem came back. AHA! I left everything alone and tested it a couple more times each day for a few days. Each time was the same, with the stock starter I could cause or fix the problem by connecting/disconnecting the VR shield jumper.

Today I installed the hi-torque starter since I thought I had proved that wasn't the problem and lo and behold, the VR sensor signal with the hi-torque starter was garbage no matter what I did. So I feel vindicated since the starter did turn out to be a problem. Either this hi-torque is degrading somehow, or they all throw out a LOT more EMI than a stock starter. Once I installed the new rebuilt starter I ordered, everything went back to working depending on the VR shield jumper.

I couldn't have solved this issue without finding both contributing factors. Now I'll replace the VR sensor wire completely and improve the grounding setup of the shielding. This improvement will reflect in all future versions of my MicroSquirt setup as well.

Tomorrow I need to solve the 70psi fuel issue as well, and then...finally...I can try starting the car. (IMG:style_emoticons/default/ohmy.gif)
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crash914
post Mar 5 2017, 06:07 PM
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Great news! I think that the MS only uses the VR sensor for a couple of revs anyway? I think I saw a video of it being removed after starting. I can believe that the starter is very noisy, just when you need to get a stable VR signal.

Glad you figured it out!
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Spoke
post Mar 5 2017, 06:32 PM
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Good news.
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sixnotfour
post Mar 5 2017, 06:48 PM
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McMark
post Mar 6 2017, 07:16 AM
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QUOTE(crash914 @ Mar 5 2017, 07:07 PM) *

Great news! I think that the MS only uses the VR sensor for a couple of revs anyway? I think I saw a video of it being removed after starting. I can believe that the starter is very noisy, just when you need to get a stable VR signal.

Glad you figured it out!

My setup only has crank trigger, so without it there is no RPM or TDC info for the ECU. Without those it has no idea when to fire injectors and definitely no idea when to fire the coils. So for this setup, a good clean signal is vital.

Thats the reason I spent so much time dealing with this before I've even tried to start the car. Without a good clean VR signal nothing can happen and if the starter is mucking with the VR signal then it's plausible that the coils or any other EMI source could have an effect as well. And those problems would be transient and almost impossible to chase down later. So we spend the time now and solve the problem because to solve it later is triple the work. (IMG:style_emoticons/default/wink.gif)
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aircooledtechguy
post Mar 6 2017, 01:10 PM
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Have you guys considered switching out the VR sensor for a hall sensor of the same size? The hall sensors are not effected by EMI like the VRs are. I dumped my VR a few years ago because of intermittent EMI issues that would induce a random miss.

May be at least worth looking into going forward. Glad you got a handle on it.
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McMark
post Mar 6 2017, 01:14 PM
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It's something to keep in mind. But I haven't had any issues with this setup on my car, and now that Zach's is sorted we'll see how it goes. Nothing is ever ruled out completely. (IMG:style_emoticons/default/wink.gif)
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McMark
post Apr 3 2017, 08:40 AM
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(IMG:style_emoticons/default/driving.gif)


Attached thumbnail(s)
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ConeDodger
post Apr 3 2017, 09:07 AM
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QUOTE(McMark @ Apr 3 2017, 11:40 AM) *

(IMG:style_emoticons/default/driving.gif)


Road test! (IMG:style_emoticons/default/w00t.gif)
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crash914
post Apr 3 2017, 10:36 AM
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No sound? (IMG:style_emoticons/default/confused24.gif)
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McMark
post Apr 3 2017, 10:38 AM
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QUOTE(crash914 @ Apr 3 2017, 12:36 PM) *

No sound? (IMG:style_emoticons/default/confused24.gif)

It's a picture. (IMG:style_emoticons/default/confused24.gif)

Fine, here's your sound. (IMG:style_emoticons/default/beerchug.gif)

https://www.youtube.com/watch?v=Zs9qq_sfeAI
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Mike D.
post Apr 3 2017, 11:04 AM
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OK, It runs now, and pretty good too!
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So... It takes 6 years for a megasquirt conversion...? (IMG:style_emoticons/default/poke.gif)

JK... (IMG:style_emoticons/default/shades.gif)
I've only been thinking about it for 6 years. Can't pull the trigger...
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ejm
post Apr 3 2017, 11:14 AM
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QUOTE(Mike D. @ Apr 3 2017, 01:04 PM) *

So... It takes 6 years for a megasquirt conversion...? (IMG:style_emoticons/default/poke.gif)

Has it been that long since we saw Zach's car at Hershey? (IMG:style_emoticons/default/biggrin.gif)
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VaccaRabite
post Apr 3 2017, 07:24 PM
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Mark said my 2056 dynoed 130 HP and 140 TQ at the wheels.
I'm pretty pleased at that. Looking forward to getting the dyno chart.

Really looking forward to driving my car.

Zach
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r_towle
post Apr 3 2017, 07:28 PM
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QUOTE(Vacca Rabite @ Apr 3 2017, 09:24 PM) *

Mark said my 2056 dynoed 130 HP and 140 TQ at the wheels.
I'm pretty pleased at that. Looking forward to getting the dyno chart.

Really looking forward to driving my car.

Zach

Well holy shit.
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