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Old 07-31-2020, 12:03 PM   #1
90volvo
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Default datalog shows alot of noise

My datalogs shows Im picking up alot of noise from my tps and cts. I checked my gounds they are good. Should I turn on noise filter in tunerstudio? or? Thank for the help.
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Old 07-31-2020, 04:50 PM   #2
90volvo
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So I redone all my grounds, they all go to engine ground which is same place battery ground connects. Also found a black wire in the extra bundle that I grounded and things are alot better. Thanks
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Old 07-31-2020, 05:58 PM   #3
740atl
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Sensor grounds should go back to ms. TPS, IAT, CLT, wbo2.
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Old 07-31-2020, 06:44 PM   #4
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740atl is correct. If you check the recommended practice in the mega manual for the MS2 version 3 board you will see that the ground for the TPS, IAT and CLT are brought back to pin 19 on the DB 37 connector.

http://www.megamanual.com/v22manual/mwire.htm

If you check the schematics, you don't have to common them on pin 19, there are other grounded pins that are available. If you have a wideband O2 and the controller has a separate signal ground from the heater ground the signal ground should be brought back to the DB 37 connector. If the wideband has a common ground for signal and heater circuits that ground should not be at the DB 37; but, at your common engine ground point.

Are you doing ignition control using the BIP 373 on the MS3 board for ignition control? If so, that has significant potential for coupling lots of electrical noise in to the MS environment.
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Old 07-31-2020, 07:01 PM   #5
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Well it was wired to the megasquirt the first time around. I guess I need to change it back to the way I had it. My ignition is stock 2.4 60/2 setup. Searching on google, looks like noise issues are common problem with MS. Thanks for the help.
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Old 07-31-2020, 10:14 PM   #6
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Quote:
Originally Posted by 90volvo View Post
Searching on google, looks like noise issues are common problem with MS. Thanks for the help.
I think it is only common because its common for people get sloppy with the wiring. Its not a design problem. I have never had noise present on my sensor inputs (at least in the spectrum that the A to Ds could capture on a log). The only voltage transient problem I ever had was when I was still using the signal off of the coil neg terminal for my tach signal. I had a faulty ignition coil wire which was flashing over on the coil tower and generating voltage spikes on the tach line which was causing resets on the processor. Replacing the coil wire fixed the problem and switching to optical sensors for the cam and crank signals eliminated the possibility of the problem ever occurring again.
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Old 07-31-2020, 10:45 PM   #7
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Quote:
Originally Posted by 142 guy View Post
I think it is only common because its common for people get sloppy with the wiring. Its not a design problem. I have never had noise present on my sensor inputs (at least in the spectrum that the A to Ds could capture on a log). The only voltage transient problem I ever had was when I was still using the signal off of the coil neg terminal for my tach signal. I had a faulty ignition coil wire which was flashing over on the coil tower and generating voltage spikes on the tach line which was causing resets on the processor. Replacing the coil wire fixed the problem and switching to optical sensors for the cam and crank signals eliminated the possibility of the problem ever occurring again.
Gotcha thanks for the info. I’ll trace down proper terminals run grounds back to the ms.
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Old 08-01-2020, 12:22 AM   #8
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As has been posted, the sensor ground wire[s] need to be completely separate from the high power component ground wires. Sensors are TPS, CLT, IAT, Crank/Cam, WB02 signal, etc. The high power components are injectors, ignition module/coil, IAC, fuel pumps, and WB02 heater power/ground.

For MS, the noise issues are usually low frequency IR drops. Think about a [normal] football season party. The fans are in the TV room making a lot of noise, with not much important content. The non-fans are in the kitchen carrying out a quiet nuanced conversation. Works fine when separated into two rooms, but doesn't work so well when everyone is in the same room.

For MS grounding, the low current sensors need to use a quiet ground. The high current components need to use separate ground[s], or else the high current switching will corrupt the sensor readings, e.g. the quiet conversation is drowned out by the high current football fans.

[If you want to see a disturbing presentation that only a geek engineer could appreciate the tone deafness, see the first couple minutes of Bruce Bowling's [aka megasquirt creator] "Noise - it's all your fault" presentation from MegaMeet 2008 -NSFanywhere]
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