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Engine Bridge and PMag's-PLEASE READ IF USING

F

F18Sailor

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I recently installed the Engine Bridge Data Monitor, connected to a pair of eMag Air (now Hartzell) pMag v114's, and have less than 10 hours on the setup. Word of caution: do not send a "save command" while changing timing settings airborne. This is in small font in the engine bridge manual:

"Note when changing settings in PMag, itis recommended to do so on the ground(with or without the engine running). A slight engine “miss” may be noticeable while the PMag is saving the data as during the few milliseconds the PMags need to save the new settings to its internal memory; the coils are not firing."

I have Pmag firmware v41 installed, updated ignition timing airborne, hit send, then clicked "save". One pMag did not reboot. Lost a mag for ~1 minute while I troubleshot the issue. Sending another command (pMag Setting) solved the issue. I was VFR at the time and well within glide distance of a runway, so manageable, but gets your attention.
 
As an add on, I'm thinking of only hooking up my engine bridge on the ground. Anyone played with this? I'm not planning on starting with the engine bridge, just doing the jumper in and a clock at TDC plus two teeth until I get the engine past break in, just so I don't have any accidental issues. Then playing with the engine bridge later and on the ground.
 
I haven't played with that option, but I believe several mechanics use the Engine Bridge in place of the EICAD software that isn't readily available and buggy on newer windows laptops. The downside is you lose the ability to monitor the pMag's in-flight. I think that is a valuable feature, assuming it works correctly and the wiring is robust. In theory, if your connections become loose, the pMag remains operating in the programmed B-curve (hence my warning).

Personally, I also like understanding what my magnetos are doing; I have the advance angle displayed on my Dynon displays and of course logged. It is a pretty big factor in CHT's; if I set to a fixed data plate timing value my CHT's are well in-line with others, 360-375 °F in cruise and under 400 °F in climb. Allowing the ignition timing to advance and I'm typically 390-400 °F in cruise across my cylinders. Yes, more work can be done on my baffles (they are not perfect and not new), but I now have the ability to correlate CHT's with fuel flow, MAP, EGT's AND advance angle.
 
Experimenting is fine, just know what you are doing and how to back out of it if needed.

For others reading posts like this, I suggest that for 90% of pMag users installing with jumpers in at whatever timing you want fits the bill. 20+ years of trouble free flying behind dual pMags and never felt the need to monitor pMag timing, or dynamically adjust it.

Side note - on my first build I installed dual LightSpeed Plasma II+ ignitions with the timing readout and timing adjust knobs on the panel. This was a lesson learned for me as after I played with it I found I never touched it again. In the end this system had numerous failures, driving my replacing them with dual pMags.

Current install is on an IO-360-M1B. Normal operations is WOT from take off to cruise altitude (8K’-10K’). I start leaning at 4K’ keeping EGTs at about that for takeoff roll (1250-1300). CHTs remain below 400. Level off, pull the prop back to 2480 or so and lean to ~20 degrees LOP. The engine controls don’t get touched again until descending for landing.

I set base timing a 25 degrees BTDC, but have no issue if anyone wants to set it at 22-23 degrees BTDC (normal compression, parallel valve engines).

Carl
 
Not the bridge, but I did run two harnesses inside terminated to female D-subs. Male D-subs have the jumper. They are secured under the panel when not in use. I use a laptop with Emag 3.0 when I want to adjust. Lately I'm running one tooth After TDC. Engine seems pretty happy.
 
Carl Froehlich said:
Experimenting is fine, just know what you are doing and how to back out of it if needed.

For others reading posts like this, I suggest that for 90% of pMag users installing with jumpers in at whatever timing you want fits the bill. 20+ years of trouble free flying behind dual pMags and never felt the need to monitor pMag timing, or dynamically adjust it.

Side note - on my first build I installed dual LightSpeed Plasma II+ ignitions with the timing readout and timing adjust knobs on the panel. This was a lesson learned for me as after I played with it I found I never touched it again. In the end this system had numerous failures, driving my replacing them with dual pMags.

Current install is on an IO-360-M1B. Normal operations is WOT from take off to cruise altitude (8K’-10K’). I start leaning at 4K’ keeping EGTs at about that for takeoff roll (1250-1300). CHTs remain below 400. Level off, pull the prop back to 2480 or so and lean to ~20 degrees LOP. The engine controls don’t get touched again until descending for landing.

I set base timing a 25 degrees BTDC, but have no issue if anyone wants to set it at 22-23 degrees BTDC (normal compression, parallel valve engines).

Carl
Click to expand...

Carl, 100% agree with you and how you operate. Lately I've been flying a mix of cross-country flights and air-work flights. When you pull power low down with the pMag's, you're also going to be on the upper end of the advance curve. That is not ideal for stalls, lower power climbs etc. I think for these type of operations setting the mags to fixed timing is a reasonable compromise.
 
wirejock said:
Not the bridge, but I did run two harnesses inside terminated to female D-subs. Male D-subs have the jumper. They are secured under the panel when not in use. I use a laptop with Emag 3.0 when I want to adjust. Lately I'm running one tooth After TDC. Engine seems pretty happy.
Click to expand...
Smart.
 
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