No tach signal

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No tach signal

Postby webehardy » Fri May 04, 2012 12:51 pm

My application is 4 cyl, coil on plug, wasted spark firing 2 at a time, with 4 wires coming out of the ECU for spark control.The ECU version is MS2extra v.3.0 purchased assembled. TS is showing good signals from all sensors except the tach, which shows no rpm when cranking. VR sensor & toothed wheel (60-2) is new from Electromotive, mounted on the crank pulley. I tried a volt meter across the VR signal wire and ground wire at a connector and got 0.5 vac while cranking. I tried switching the VR polarity using jumpers at the VR cable connector - still no RPM. I tried changing the VR sensor gap from .040" to .032"- still no RPM. And I tried adjusting R56 and R52 in the ECU to see if the signal would trigger - still no RPM.
Is it possible that I made a faulty setting in the ECU that prevents the transmission of the VR signal ? It seemed to work when I had the 'Jim Stim' attached.
I have attached the MSQ. A datalog shows nothing without RPM. Thanks for your advice.
65 S-600 ms2 2012 5 4.msq
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Re: No tach signal

Postby .boB » Sat May 05, 2012 11:32 am

Use the tooth logger and see if you're getting a tach signal from the Hall sensor when the engine is cranking. If not, you need to start there.

With power on, place the sensor over the missing tooth gap. Then pass a metal object across the face of the sensor. You should get a blip on the tooth logger. If you you do not, then there's something wrong with your sensor circuit.

If you do get a blip on the tooth logger, then the sensor and circuit is working, but it's not getting a good trigger.
- what voltage are you feeding to the VR sensor? Although the range may be 5-25v, it may perform better at a specific voltage. Mine performs poorly at 5v, but excellently at 12v.
- the air gap is pretty small. Especially if the sensor body is not perfectly aligned with the trigger wheel. Mine works best if you screw it in until it touches the tooth, and then back it off 1/2 turn.
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Re: No tach signal

Postby webehardy » Wed May 09, 2012 2:53 pm

I do not see a tach signal on the tooth logger when cranking while the logger is recording, and I see no spike on the tooth logger when I tried your suggestion and tested it not cranking, using a iron object at the tip of the VR sensor as an on/off switch. The only positive response I have seen, is in measuring the AC voltage while cranking which goes from zero to 0.5vac when I energize the starter ( spark plugs removed). So, If the sensor is putting out a signal, the ECU is unable to read it.
I am unsure of myself in manipulating TS and MegaLogViewer, so I could easily have messed up a procedure or basic entry that interfered in some way. I spend time nearly every day trying get familiar with these programs, but I'm not comfortable with them yet.
Thanks again for your input.
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