Noise in Cam and Crank Signal

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Noise in Cam and Crank Signal

Postby okubricko » Thu Aug 31, 2017 8:26 am

I edited the title of this post to more reflect where things are now with my build. I didn't want to start a new thread. See the last few posts.

Hey all, thanks for looking at this. I have my MS3X in my vehicle and am at the point where I'm running my first tests of the Tooth and Composite Logger. The pictures below are my output. I think that they look like they should but wanted to get extra eyes on it. I'm running a 36-1 crank trigger with a single tooth cam trigger on a four cylinder engine. In the composite logger I can see some sync errors at first but then they disappear and don't show up after those initial blips. The crank signal looks good, uniform and show the engine compressions. The single tooth cam signal is also showing. My question on this is should that signal look like a single point of a wave?

Composite Logger First Test.jpg
Composite Logger First Test.jpg (90.64 KiB) Viewed 475 times


Below is the tooth logger. To me this also looks correct. Single long line for the missing tooth and then the compression cycles.

Tooth Logger First Test.jpg
Tooth Logger First Test.jpg (88.69 KiB) Viewed 475 times


Any input would be appreciated. Thanks again.
Last edited by okubricko on Sat Sep 02, 2017 7:32 am, edited 1 time in total.
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Re: Confirmation before Proceeding

Postby jsmcortina » Thu Aug 31, 2017 8:41 am

All looks ok to me.

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Re: Confirmation before Proceeding

Postby okubricko » Thu Aug 31, 2017 9:56 am

thanks much James
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Re: Confirmation before Proceeding

Postby okubricko » Fri Sep 01, 2017 8:00 am

So after doing all the pre-start checks in the manual before cranking I didn't get it to fire, just pops and cranking. I did a quick composite log and get this.

Composite Logger First Start.jpg
Where does the extra cam signal come from? It's at the same time as the sync loss
Composite Logger First Start.jpg (121.03 KiB) Viewed 437 times


Am I getting interference or battery voltage drop? I am guessing some interference due to the extra cam signal. I'll check to make sure the crank sensor hasn't shifted. Just looking for other opinions.
Last edited by okubricko on Sat Sep 02, 2017 7:35 am, edited 1 time in total.
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Re: Confirmation before Proceeding

Postby billr » Fri Sep 01, 2017 9:45 am

Post a tooth-log from an actual starting attempt as well as...

:msq:
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Re: Confirmation before Proceeding

Postby okubricko » Fri Sep 01, 2017 10:29 am

Attached are two tooth logger pictures. The first one picture is the initial start of cranking which looks good, but then the signal goes haywire.
Tooth Logger First Start 1.jpg
This is the tooth log during the first couple of cranks
Tooth Logger First Start 1.jpg (75.63 KiB) Viewed 427 times

Tooth Logger First Start 2.jpg
Then the signal gets bad
Tooth Logger First Start 2.jpg (77.42 KiB) Viewed 427 times


MSQ as well.
Betty - CurrentTune.msq
(283.91 KiB) Downloaded 13 times
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Re: Noise in Cam and Crank Signal

Postby okubricko » Sun Sep 03, 2017 6:45 am

I'm wondering if this is a voltage issue. I have a 14point7 O2 gauge that had a backlit LCD screen. When I crank the engine I notice that the backlight on the screen goes on and off. I'm guessing the voltage drop is causing the interference.
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Re: Noise in Cam and Crank Signal

Postby billr » Sun Sep 03, 2017 9:07 am

Well, hard to say without the MSL (datalog) file...

:msq:
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Re: Noise in Cam and Crank Signal

Postby Exidous » Sun Sep 03, 2017 12:39 pm

Many position sensors are tolerant of voltage drops as is the MS series. They'll usually still work down to about 6volts. If you were lower than that I doubt you'd even be able to crank.

I know that doesn't help much but at least you can possibly rule out the voltage.
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Re: Noise in Cam and Crank Signal

Postby okubricko » Sun Sep 03, 2017 2:46 pm

Sorry, here is the MSL.

2017-09-03_17.44.19 - Noise.msl
(112.45 KiB) Downloaded 8 times
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Re: Noise in Cam and Crank Signal

Postby billr » Sun Sep 03, 2017 7:05 pm

Well, battery voltage is only falling to 9.8; that should be OK.

What kind of crank/cam sensors (VR, Hall, other)? If Hall, what voltage is the supply, what pull-up resistance to what voltage? All wiring for those sensors is shielded, with the shield grounded at only the MS end? Is any wiring shared by both the CKP and CMP sensors?
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Re: Noise in Cam and Crank Signal

Postby okubricko » Fri Sep 08, 2017 11:41 am

Sorry for the delay in getting back to this, I was out of town. The Crank sensor is a VR, Cam is a Hall. The VR is shielded per the manual, I need to check to see if it's grounded at the sensor because I have it grounded at the MS3X. Although, I tried disconnecting the ground at the MS3X but still got the same noise in the signal. The Hall cam sensor is aftermarket and is powered with a +12v supply and has a built in internal pull up resistor. It's designed to be used with megasquirt.

Quick question, I've read this both ways. Does a Hall Cam sensor need to have JP7 jumpered or no?

There is shared wiring. I used a terminal block and ran all the sensor grounds to it and then I have one lead off the the terminal block run to pin 7 on the MS3X. Grounded at Pin 7 on MS3X - IAT, CLT, OS, Cam, Crank, O2, LS2 Coil sensor grounds, Flex Fuel. Should I only have actual sensors grounded at pin 7 and utilize the other ground points on the MS3X for things like O2, LS2 Coils?

I was just looking at the manual and the Flex Fuel sensor should probably be grounded to the engine and not the MS3X. I'll have to move that over.

I have done the same for everything that needs +12v. Power from the relay goes to a single point and then is distributed to all the individual sensors and outputs that need +12v. LS2 Coils, Injectors, Idle Valve, Flex Fuel.

I think in the meantime while I'm waiting for words of wisdom from here I'll start by disconnecting everything except the Crank and Cam, try cranking and see what happens. If no noise, I'll slowly add things one by one and see when the noise appears. I'll also make sure that the Flex Fuel sensor doesn't go to sensor ground.

Thanks.
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Re: Noise in Cam and Crank Signal

Postby billr » Fri Sep 08, 2017 1:24 pm

If the Hall sensor has a built-in pull-up, I would removed the jumper at JP7 on the MS3X.
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Re: Noise in Cam and Crank Signal

Postby okubricko » Wed Nov 15, 2017 7:01 am

I thought I'd come back to this thread and wrap it up in case anyone else has a problem like this.

The sync loss was coming from a weak battery. My signal would be great at first and then degrade. I replaced the battery and have eliminated all problems.
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