The day to install the RV-8 instrument panel finally arrived.  I refuse to do the "upside down, on your back, head on the floor" routine when doing work behind the panel so mine is completely modular with connectors on everything so it can be easily removed and replaced for repairs or modifications. I had very carefully wired and checked everything twice and done 99% of it in the comfort of my shop where it is easier to avoid errors.

With great anticipation I switched on the flight critical and avionics breakers eager to see everything come alive with all the expected readings.    Dang!  The dreaded NOP is flashing in the Tach window of the EM2 indicating no data link communications with the EC2.  Checked the wiring of the two wires involved and sure enough, one of them was on the wrong pin (switched with another wire on same connector).

Fixed that and the NOP was gone but getting a lot of screwy readings on many (actually most)  engine parameters.  Attacked them one by one and started to notice a pattern.  They were all on the same row of pins of the same connector as the NOP problem.  Yep, I had wired them all starting from the wrong end of the connector.   Since the cable was already wired into the plane I had to fix it in place.  Bad job even with the instrument panel removed  but I can't imagine having to do it with the panel still in.

That made things a lot better but still had a lot of screwy readings.  EGTs were drifting around, pressures were all high (above redline)  and coolant & oil temperatures were no where near room temperature where they should be.  Only thing looking normal were the 5 air temp channels.

These were all grounding problems.  Teflon tape and anodized fittings prevented ground connection on many sensors, and the ceramic coating on the exhaust manifold managed to isolate the EGT probes which must be grounded at the probe.   There was also a missing ground strap from engine block to firewall.  This didn't cause damage since I did have a cable going from starter mounting bolt directly to neg terminal of battery which is way back behind the rear seat baggage area (for CG reasons).   The small voltage drop through this cable was still enough to cause the engine to rise above ground potential and this offset affects the instrument readings a bit.   Not sure what would have happened if I had tried to start the engine though.  The voltage drop would be a lot more with 100+ amps of starter current.

The urge to hear the object of so much labor and love come to life is almost irresistible but It is a good idea to solve all of these problems before hitting that starter switch.

Tracy