Tach signal and EFI, Megasquirters and Subaru converters please read... |
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Tach signal and EFI, Megasquirters and Subaru converters please read... |
falcor75 |
Jul 25 2016, 01:39 AM
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#1
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Senior Member Group: Members Posts: 1,579 Joined: 22-November 12 From: Sweden Member No.: 15,176 Region Association: Scandinavia |
I'm running my 2.0 four cylinder with an aftermarket ECU.
In the settings for the tach signal I've selected 12v, 50% duty and this worked fine for a few months of testing. The day before my dyno session the tach started behaving wierdly. It would start up fine but after a little bit of running it would settle between 3k-4k rpm. Revving the engine would momentarily get it back to normal but after a few seconds at constant rpm it would return to its new favorite position. Any ideas what could be causing this? |
falcor75 |
Jul 25 2016, 02:19 PM
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#2
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Senior Member Group: Members Posts: 1,579 Joined: 22-November 12 From: Sweden Member No.: 15,176 Region Association: Scandinavia |
The signal is on a dedicated tach output from the ECU, and I can set it to either 12v or 5v with 50% duty cycle or a duty cycle I choose myself.
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stugray |
Jul 25 2016, 02:30 PM
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#3
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
The signal is on a dedicated tach output from the ECU, and I can set it to either 12v or 5v with 50% duty cycle or a duty cycle I choose myself. So the ECU reads the actual tach signal from the coil, then 'conditions' it and routes it back out to the TACH as a +12 or +5VDC signal? That sounds a lot like my setup using the MSD 6AL. There is a +12V 'TACH' signal that comes out but the Stock TACH could not read it. So I used the MSD Tach-Adapt like shown above. HOWEVER - the TACH signal that goes INTO the Tach Adapt has to be capable of relatively high current, so check to be sure the Megasquirt tach signal you intend to use is capable before you try it or you could fry it. |
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