Engine Sensors & Wiring

I need to get caught up - I've gotten a fair bit done on the FWF, but recently it's been in 10 minute increments, which aren't as easy to document in a meaningful way.  There is so little information provided about the install of the engine and FWF systems that it can sometimes take me an hour or two to research something that takes me 10 minutes to actually do.  So I'll get one thing accomplished, then have to spend the evening trying to sort out the next 10 minute task.

The manifold air pressure line goes from a fitting in the outer aft corner of cylinder 3, through the firewall and to the sensor.  The engine came with a plug in the sensor port, which is fairly normal I suppose, since not everyone measures MAP.  After my experience getting the oil pressure plug out, I was a little nervous about doing it again.  Turns out, I had reason to be.  You wouldn't think that threads would be seized on such a new engine that's barely been run, but between whatever thread sealer they use and the paint over the top of it, this one didn't budge!  I tried very gingerly for an hour with nothing to show for it except a slowly rounding off hex head (I tried hammers, heat, you name it).  The hex was getting rounded off enough that I knew I was running out of time to break the plug loose.  I put an allen socket in my impact driver and crossed my fingers that the impact  would break the plug free at least a little.  Nope.  After that attempt, the hex head was completely rounded off.  I'd read that this wasn't an entirely unusual situation, but that didn't make me feel much better!  Since I had no other choice at this point, I drilled the head of the plug slightly larger and deeper (making sure not to break through the back) and used a bolt extractor.  Finally, after tons of heat and hammering, I was able to break the plug free.  It only took me a few hours!

The MAP line that Van's sent is much longer than I need it to be, but it sets in a pretty natural curve against one of the engine mount arms, so I'll just use the length to my advantage and clamp it to the mount.

The name of the game for mounting items FWF is using multiple adel clamps - one to hold the wire/hose and one to hold the first clamp to the mount.

There is a fitting high up on the engine just in front of the oil filter that is for the oil breather line.  Van's provides a piece of rubber hose as well as a big aluminum tube for the breather line.  Unfortunately, the angle adapter I have for the oil filter puts the filter in the way and doesn't allow as straight of a shot as the plans show.  I cut the rubber hose down to essentially just have the 90 degree elbow, which I clamped to the engine fitting.  I did a bunch of bending of the aluminum tube to get it to fit into the rubber hose and then run down the firewall (it'll have an adel clamp to hold it to the firewall), but can't finish it up yet until I have the tailpipes on.  The opening of the breather is supposed to be just above the tailpipe, so any oil blown out just drips on the hot tailpipe and burns up.  I won't know exactly where to put the tailpipes until I've done a basic fitting of the lower cowl.  So as usual, this is a task that has to stay partially done for now.

If you look on the other side of the filter, you can see the aluminum portion of the breather line.  It has a flared portion at the top to fit into the rubber hose, then curves down to the firewall.

One other partially completed area was the amp shunt and ANL fuse holders.  I probably could have just finished up by using large gauge wire, but I didn't have the few inches of wire that I needed, let alone the various ring connectors.  I had a chunk of 1/16" copper left over, so I decided to go with that instead.  The copper bar from the shunt to the primary 60A ANL fuse was straight forward.  I THINK I could have just taken a second short bar from the 60A fuse holder to the second fuse holder, but the advice I got from the alternator manufacturer (B&C) was to fork off at the shunt to go to the second fuse.  I'm pretty sure the electricity doesn't care (and the alternators have diodes in them. so there's no way for current from one alternator to flow into the other one), but I didn't care enough to spend another 2 hours trying to find an answer.  I decided to just cut out a chunk of copper to go from the shunt to the second (40A) fuse holder.  This 40A fuse will be the spot for a future backup alternator.  With this work done ahead of time, adding a backup will be as easy as installing the alternator and wiring it to the ANL fuse.  I didn't have any heat shrink large enough for this copper bar, so I dunked it in Plasti Dip.  That stuff is kind of addicting.  After seeing it work, I wanted to wander around the garage and find other things to rubberize.  I snapped the covers onto the fuse holders.  This is all done now and ready for an alternator, which I still need to order.

Next up, the cylinder heat temperature sensors.  It took me an embarrassingly long time to figure out where the ports were for these!  They go underneath each cylinder head, but you can't actually see the  holes unless your under the engine looking up.  The sensors have a threaded adapter that screws into the engine, then the sensor slides up through that adapter.  The first 5" or so of the sensor are covered in a spring, and the twist on connector uses that spring to provide some pressure against the sensor to ensure it bottoms out against the cylinder wall.

Here you can see one of the CHT sensors in place.  It is directly behind and underneath where the lower spark plug will be.  I haven't figured out how I'm going to route the wires yet.  I need to get everything in place before I start committing to wire routing.

The exhaust gas temperature probes insert into the exhaust a few inches below the attachment flange.  The AFS manual says they need to be at least 1 1/2" below the flange and ideally no more than 3", with the location being consistent from one exhaust to the next.  Each exhaust has a curve to it in a slightly different location, so I just had to go for the best compromise, which ended up being 2 1/2" inches below the flange.  I measured about 50 times and then drilled a #30 hole into each exhaust stack.  The probes on the left side of the engine point out and back, but the probes on the right side of the engine actually have to point forward and out in order to not be in the way of the lower spark plugs.  I checked a number of pictures online, including of a few of Van's demo planes, and they all have these right side probes facing forward.  Once the probes are inserted into the exhaust, a hose clamp snugs them up (there's a little flange on the probe that the hose clamp pulls against the exhaust).

Here I thought I was done with the rat nest of wiring, but time to do it again!  I pulled the EGT/CHT wires (the brown ones) through the firewall from the EMS module, and started laying out the wiring for the rest of the FWF stuff (the rainbow harness).

I went through the wire harness and labeled each wire so I could start to figure out where it goes, and ultimately what path they all have to take.  It turned out that there were about a dozen wires in the harness that I won't use - some because I'm using the ACM, and some that are simply for other types of engines, like carbureted.  I thought about just looping up the wires and leaving them in the harness, but I decided it would be a lot cleaner if I just took all of the wires that I don't need out of the Dsub.  So I spent some time unpinning the wires, then also adding in a few additional wires, like for the fuel take senders.

The EMS module has two big Dsubs that go into it - one is the EGT/CHT wiring and the other is for everything else.