EIS Tach fluctuation issues
Posted: Mon Mar 25, 2013 3:13 pm
I have intermittent runup tach readings on an IO-360 with dual slick mags, both Tach 1 and Tach 2 wired through 27K resistors.
I have verified the wiring, checked the resistor values, removed the resistor spade plugs and soldered the resistors in, changed plugs and recently installed an optical tach on the dash.
I see a variation of hundreds of RPM at runup on the EIS data - it does not show on the optical tach. I have verified the P-lead wiring and grounding when switching mags.
I have tried both H and L filtering in the EIS setup and only L is usable - H results in fluctuations all the time.
In the air - all is well on both mags and always has been.
I'm in the process of gathering log data on both ground and in-air mag checks to see what happens to the tach signals, but I thought I'd ask if anyone has any more ideas.
I belive this to be a sensor issue and not an actual RPM fluctuation as it doesn't show on the optical tach or the seat of the pants.
Scott E
RV-8
26 Hrs in Phase 1!
I have verified the wiring, checked the resistor values, removed the resistor spade plugs and soldered the resistors in, changed plugs and recently installed an optical tach on the dash.
I see a variation of hundreds of RPM at runup on the EIS data - it does not show on the optical tach. I have verified the P-lead wiring and grounding when switching mags.
I have tried both H and L filtering in the EIS setup and only L is usable - H results in fluctuations all the time.
In the air - all is well on both mags and always has been.
I'm in the process of gathering log data on both ground and in-air mag checks to see what happens to the tach signals, but I thought I'd ask if anyone has any more ideas.
I belive this to be a sensor issue and not an actual RPM fluctuation as it doesn't show on the optical tach or the seat of the pants.
Scott E
RV-8
26 Hrs in Phase 1!