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Couple SDS CPI2 install questions

Cross posted from another site, so some of you may see this twice.

I've had to let my chase plane buddy know that I'm postponing my first flight, which was to be tomorrow morning.

Turns out that on my first actual "mag check" with my dual SDS CPi2 setup, it's only running on one side. I can't believe I got this many engine runs into the project before using the A-B/L-R test function, but it's due in large part to my lack of understanding how completely the backup battery function takes over on these things - the power switches they say are required to turn it all the way off do NOT kill backup power to it and thus DO NOT substitute for a mag check done by grounding each side of the ignition by key-switch or by keypad menu entry. After I figured this out and actually did a true "mag-check" yesterday, the engine died with the key switch in the R or OFF positions but ran in L or BOTH. Same when tried with keypad. Left a voicemail at the shop 4:30 yesterday and called Barry's number later Friday evening - calls have not been returned yet. Given their reputation for customer service and my own prior experience, I know I'll hear from them at some point.

My other issue is that the ignition often lights off a charge when I first power it up. :eek: Typically it just kicks a blade back 60 degrees or so (still a hazard to anyone near the prop at that point!) but last night it fired one that sounded like a .44 mag without ear pro. Blew soot and fuel all over the floor of the hangar. Okay, I _might_ have had a hot start flooding issue just before that... This behavior is now no longer something I can ignore. A pilot should not expect an untouched prop to move by itself before cranking is begun. It's too easy to leave an ignition toggle on at shutdown and have the prop kick back the moment the Master is turned on - has already happened to me. Barry said it's a reported issue and he had a software type of fix for it but I'd have to send the CPU's back to him. Given the difficulty of access to my units and the approaching first flight target date, I decided at first to live with it and mitigate by powering up the CPU's first and then the coil packs (my left-to-right toggle sequence is LEFT COIL, LEFT CPU, RIGHT COIL, RIGHT CPU). Next time I tried this the fuel-air charge lit off as soon as I powered up the LEFT CPU with the coil pack switch still OFF!

It's obvious the unit is capable of discharging all plugs at once on power-up regardless of power/no power on the red wire to the coil pack, and one of these spark events will be on a cylinder with some residual fuel-air and sometimes an open valve or two.

What I've learned for certain is that mounting the CPU's way up under the forward skin between firewall and sub-panel was a big mistake. There were not any other attractive options I could see with the real estate taken up by the Advanced QuickPanel remote components, but I mounted them over the rudder pedal cross tubes thinking I'd never have to touch them again for the life of the airframe - and honestly, I shouldn't - but now I do. As it is, the seat and joystick must come out just to allow the tortuous yoga position needed for unbolting the ECU's from the stringers I put across the ribs from firewall to sub-panel.

I'm thankful to have found this issue before I naively launched on one ignition. I feel divinely protected from my own ignorance and folly once again.

We've seen the popping issue sometimes on installations where there are no coil power switches (coil power comes on with the master). Just had another one last week. We'll send you a new ECU to address this as soon as Barry is back from vacation on the 8th. In the meantime, you can pull the coil power breakers so this doesn't happen.

As far as the 2nd coil not firing, that could be a few things. I'll forward this to Barry and he should be able to respond today sometime by email.

I'm very sorry for the trouble here and the difficulty in getting the ECU out of there again. I'd be pissed too.
 
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That's the dilemma, Ross. There ARE coil switches. The thing fires even when they are off. And it only runs on the B-side, apparently.

I have run 4 wires from a fuse block, each individually fused, each to a SPST toggle switch, and those feed the red and purple wires to each ECU. I have a keyed ignition switch wired per SDS instructions, gray wire to the (L) terminal and the two yellow wires to the (R) terminal. I hope this is correct, as the manual states, "We need the two yellow wires connected together due to system complexity."

When I go down to the hangar in awhile I will verify these connections. I can pull the key switch easily for a second look. I hope I can check the 4 grounds and the locations of wires in ECU terminals via boroscope and camera. I know from seeing the control display power up on either purple wire toggle that those fuses are not blown, but I'll check all 4.

I plan to reverse-engineer my wiring harness by drawing what I see in the plane and then making sure it corresponds with what's in the SDS literature.

My software is v 1.4 in case this is an issue. I will also document whatever jumpers are in place on the back side of the key switch; I don't recall any but I'm racking my brain now for little things that could undermine this installation.
 
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That's the dilemma, Ross. There ARE coil switches. The thing fires even when they are off. And it only runs on the B-side, apparently.

I have run 4 wires from a fuse block, each individually fused, each to a SPST toggle switch, and those feed the red and purple wires to each ECU. I have a keyed ignition switch wired per SDS instructions, gray wire to the (L) terminal and the two yellow wires to the (R) terminal. I hope this is correct, as the manual states, "We need the two yellow wires connected together due to system complexity."

When I go down to the hangar in awhile I will verify these connections. I can pull the key switch easily for a second look. I hope I can check the 4 grounds and the locations of wires in ECU terminals via boroscope and camera. I know from seeing the control display power up on either purple wire toggle that those fuses are not blown, but I'll check all 4.

I plan to reverse-engineer my wiring harness by drawing what I see in the plane and then making sure it corresponds with what's in the SDS literature.

My software is v 1.4 in case this is an issue. I will also document whatever jumpers are in place on the back side of the key switch; I don't recall any but I'm racking my brain now for little things that could undermine this installation.

Ok, I believe I understand now. Barry will hopefully be able to respond to you by email tonight sometime.
 
We've seen the popping issue sometimes on installations where there are no coil power switches (coil power comes on with the master). Just had another one last week. We'll send you a new ECU to address this as soon as Barry is back from vacation on the 8th. In the meantime, you can pull the coil power breakers so this doesn't happen.

As far as the 2nd coil not firing, that could be a few things. I'll forward this to Barry and he should be able to respond today sometime by email.

I'm very sorry for the trouble here and the difficulty in getting the ECU out of there again. I'd be pissed too.

Not a CPI but the full SDS installation on my airplane - and I've seen the same issue. If I power up my fuel pumps, then power up the ECU (which automatically injects a fuel burst on startup) and then power up the mag coils, I will occasionally get that same pop. I've changed my start technique to Master on, the mag coils on, then fuel pump, then SDS, then crank. This way the discharging mags don't have a fuel mix to fire and I don't have the pop - but this technique requires the ability to shut off the injection completely on shutdown, as with the full SDS. Mechanical injection or carb engines that may still have fuel present are another issue.

What really needs to be solved here, and Barry may have it in process, is to disable/remove the firing pulse on the mag coil powerup routine.

Ross - if that's a hardware/firmware fix I will certainly want it too - but I'm not at a "safety of flight" or "AOG" hurry, it can wait till my annual in 6 months - that's going to be a long one anyway.
 
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Just to be clear, sometimes these "pops" are little "whoofs" and sometimes they are ear-splitting and the prop movement could be skull-splitting. All depends on the residual fuel after shut-down and where the valve timing is. I'm wiping soot off my left leading edge from where the last one escaped through the slip-joint in pipe 6. :eek:
 
Not a CPI but the full SDS installation on my airplane - and I've seen the same issue. If I power up my fuel pumps, then power up the ECU (which automatically injects a fuel burst on startup) and then power up the mag coils, I will occasionally get that same pop. I've changed my start technique to Master on, the mag coils on, then fuel pump, then SDS, then crank. This way the discharging mags don't have a fuel mix to fire and I don't have the pop - but this technique requires the ability to shut off the injection completely on shutdown, as with the full SDS. Mechanical injection or carb engines that may still have fuel present are another issue.

What really needs to be solved here, and Barry may have it in process, is to disable/remove the firing pulse on the mag coil powerup routine.

Ross - if that's a hardware/firmware fix I will certainly want it too - but I'm not at a "safety of flight" or "AOG" hurry, it can wait till my annual in 6 months - that's going to be a long one anyway.

The CPI-2 is fundamentally different from the EM-5 in that coil power isn't routed through the ECU.

Your EM-5 experience is interesting. The ECU won't fire the coils until it sees a synch mag and 2 trigger mags to establish a time interval. Powering up the coils should do nothing. Only when the field collapses should a spark occur.

My procedure on the EM-5 is to power up the ECU and then coil and injector power (separate switches in my plane). Pump goes on last but that won't make much difference if you still had fuel pressure in the lines. I shut down ECU, coil and injector power at the same time. Have never had a pop in 17 years nor in the SDS equipped cars I've driven for a couple decades.

We'll have to think about how this can happen on your installation Greg. This is a very, very uncommon problem.

We've had a hardware fix for those who see (or hear) this problem on the CPI-2 for about 30 days now. For anyone who is having this issue, please contact us and we'll get it fixed for you. In some cases, this has been a switchology issue where there is still power coming from somewhere else and getting into the ECU.
 
If we were a little closer, I'd fly to you and show you myself.

If I power up the fuel pump, then the ECU with fuel pressure available, and then power up the coils, I'll get the pop about one try in five. As mentioned earlier sometimes it's clearly a "wheeeooshhh" as a slow mixture burns through the pipes and sometimes a .44 magnum going off, depending on the mix and distribution, with significant prop movement usually on the louder ones.

I figured out the cause pretty quick, and just let the mags do their thing before I introduce fuel in the system. My start procedure works as long as I shutdown by killing injection first, so it's no big deal now, but food for thought and easily reproducible if you'd like to see it. In my plane the injector power comes on with the same switch as ECU power, two switches for the mags, and separate switches for the fuel pumps.
 
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Issue mostly resolved.

Found a faulty DC power path feeding ship's power to one of the coil packs. Fixed the problem completely as far as I can tell.

This turned out to be an ATC fuse in a fuse block not making good contact. Fuse was visually inserted all the way. Removed for continuity testing when it read no voltage on the load end in the holder. Not blown, reinserted, all works now.

This is a bit of a mentor-questioning moment in regards to the superiority of fuse blocks versus acres-of-breakers. Never seen a fuse go in tight and not make electrical contact until now.

I have as-yet unanswered questions about why this set of conditions did not illuminate the fault light nor get taken care of by the SDS backup battery system. I will wait to learn the explanation. Meanwhile that 540 never sounded so good as she does firing on two plugs per cylinder!
 
Thanks, Ross. Nobody gladder 'n me! :D

I do want to pick Barry's brain about the role of the fault light in this scenario and the function of the backup battery when he calls. It seems like losing those two coil power circuits in flight, whether by a fuse holder issue or a loss of the whole ship's DC power system is where the backup battery should take over and run the engine until depleted without missing a beat. Yet this side of the dual ignition was not running at all with this fuse fault. So I'm clearly cloudy on how this is all supposed to work. Since I get a backup battery voltage reading on the programmer screen, I assume its power path has continuity and it should be fully functional.
 
If the coil fuse or breaker is open, how is the backup battery going to power the coil? There is no other power path from the CPU board to the coil.
 
If the coil fuse or breaker is open, how is the backup battery going to power the coil? There is no other power path from the CPU board to the coil.

The switch in this case is controlling the power supply to the CPU unit; that is, it's between the ship's power distribution and the CPU. There is no switch between the CPU and the coils.
 
At least in my case, Phillip is correct - the fuse I'm referring to is a branch of my DC battery bus and feeds power to the CPU input connectors via a toggle switch. The fuses on the CPU (ECU) itself are not what we're discussing. I suspect (but don't know for sure) that it's probably really bad for engine ops if they blow.
 
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