I am still getting this frustrating miss, which seems to be emanating from the Electronic Ignition (EI). The miss only seems to happen above 2,500 RPM, which is why I never experience it on the ground. One more time, here is the setup.

I have one Slick mag set to 25 degrees and the EC3 timing was previously set to 25 degrees with the engine running at WOT, on the ground. I have 9:1 pistons, LS1 coils and Magnecor racing plug wires. Electromotive 1/2" sensors.

Yesterday, I replaced all the automotive plugs with NGK 3035 (was Denso Iridium IK27, but no local sources) and cleaned the aviation plugs - no help.

I braced the sensor support bracket - no help.

I checked and adjusted the runout of the trigger wheel to .003" - no help. I have .030" air gap between the sensor and the trigger wheel.

Today's symptoms, in flight. 5,500' msl, 6,500' D.A. OAT 62F

At WOT and ignition set to BOTH, I only get about 2,950 RPM (should be 3,100 with this prop). The engine is fairly smooth but I have seen it smoother.

On MAG only the RPMs drop about 100 RPM, but remains relatively smooth - for running on a single mag.

On EI only, I get a BAD miss. Adjusting the mixture from full rich to lean seems to have no effect.

I think that's about it. How do I fix this?

Calibrating the Oil Temp Sensor

I was hoping beyond hope that the Dynon oil temp sensor might be reading incorrectly. I was hoping that I might have a bad connection which might cause it to read high.

No such luck.

With the assistance of Prof. Charley Rodriguez I ran the engine and got it up to almost 220F. We took several comparative readings in the oil sump and found that the Dynon sensor and the lab quality thermometer agreed within a degree or two.

Today I will work on stabilizing the EFI sensor mount to eliminate the miss, then will figure how to cool the oil. I have a couple of ideas there and do have an oil cooler waiting in the wings if I decide I will go that route.

It's Hot Today - long post

So now, I have two issues - a miss in the engine at certain engine speeds and hot oil temperature. For right now, I'm just going to talk about the oil temp.

My oil temps are high, even after the addition of the aluminium sump. Let's look at what I have changed since I started on this huge rebuild.

Old *** New

Carburetor *** Electronic fuel injection

Straight inlet to carb *** Snorkels to throttle body

1 Mag & LSE ignition *** 1 mag & RWS ignition

WOT 3,050 RPM *** WOT 3,150 RPM

Steel sump *** Aluminium sump

5" prop extension *** 7" prop extension

4" inlet rings *** 4" inlet rings

Plenum baffling *** Plenum baffling

Cowling with big exit *** Cowling different, but same area

Steam gauges *** Dynon FlightDeK D180

Wing out of alignment *** New wing properly faired in.

Crappy paint *** Beautiful paint

I called Harry Hinckley, up in Iowa City, and asked if he might take a look . Harry has a highly modified Swearingen SX300 and he really knows his business and he said to come on up.

It was really hot out. Just leaving the pattern at Carbondale the OAT was 84 deg. At just 1,000' the temps started coming up so I throttled back. I had to hold it down to 2,450 RPM, then even lower just to hold the oil temp down to 230! My cylinder head temps were:

#1 - 346

#2 - 383 (#2 is consistently 50 deg hotter than the rest.)

#3 - 330

#4 - 364

When I got close to Iowa City, the ambient air suddenly dropped to 74 and my temps dropped too.

Harry looked it all over and gave more compliments than I thought I deserved. He identified three things (actually four) that I should address. He said I should have exit ramps where the exhaust exits below the firewall, I should plug all the baffle leaks to force more air around the cylinders and I should add a better ramp to smooth the air exiting the cowl. (The fourth item was to fix the miss).

We shot off to the hardware store and picked up a tube of silicone and got to work. Harry magically fabricated a couple of ramps - something I had been meaning to do for several years.

After I got the plenum off, we started caulking everything. We probably closed up 5 square inches of leaks.

The whole day, there was a sense of urgency with threatening weather to the west, and Flight Service was calling for big boomers in the P.M., but they never materialized. About 4:00 I was ready to head home and see how it helped. Harry pulled out the SX and Greg Zimmerman rode shotgun to form up and see what they could see. Harry said all the control surfaces were in alignment - so that is good, one of those things that you can't really see while in flight. He also said that it was pretty.

The air above was still in the 72 deg area, o I decided I could climb to 5,500' and maybe things would be cooler there. It was fun seeing the SX300 in formation, and naturally Harry blew the doors off of me.

But was was the result? Sadly, not much of a change. I still had to throttle way back to keep the oil temps down. My cylinder head temps were:

#1 - 316

#2 - 368

#3 - 310

#4 - 343

It appears that the cylinder head temps were better, but these were recorded with an OAT of 77 deg. Not quite sure. The oil was just as bad as ever.

I think we improved the cylinder cooling. and my Delta P (differential pressure between the top of the engine and the bottom) was higher.

This is all quite discouraging. On the two hour trip home I resolved to bite the bullet and install an oil cooler, which I really didn't want to do. It will add expense, weight, and increase overall cooling drag.

When I got home, I started looking over the Dynon support forums and I saw there was some discussion, a couple of years ago, about calibrating the oil temp sensor. When I installed my new Dynon system, I meant to do this but never did.

The proper method is to immerse the sensor in boiling water and it should be pretty close to 212. Unfortunately, the sensor is at the rear of the engine, and I have to pull the whole engine to get at it.

As I was mulling all this over at 4 A.M. today,it occurred to me that I could do this without pulling the engine. I can fly and get the engine nice and hot. Once on the ground I can have someone drop a very accurate lab thermometer that I just happen to have, into the oil pan. Can even keep the engine running. I can simple compare those temperatures and see where I stand.

If I get no luck there, I have already ordered the oil cooler parts and can start on it this weekend.

Working on the Miss

Still have the persistent miss in the Electronic Fuel Injection/Ignition (EFII) system. The symptoms are very similar to the trouble I had last year and at that time I had positively diagnosed the issue as vibration in the aluminium sensor bracket.

My first thought was to stiffen up the new steel mounting bracket, but I thought I would go after the trigger wheel runout first and see if that yielded any results. Depending which document I am looking at, the allowable runout for a 7 1/2" trigger wheel should be .003" - .006". My initial check seemed to put it at .006.

I got hold of a dial indicator clamped it in the bracket and filed each tooth until now I am about .0025" of a perfect circle.

I test flew it today and the miss was still there, but it seemed to kick in at 2,870, rather than the former 2,820 RPM. Again, I am looking for 3,100.

Now, it's time to see about stiffening up the bracket.

Wish me luck. I am so tired of all this.

Finally Smashed Some Bugs

Finally got up in the air today after being off more than seven months! Sometimes I can't believe how much I seem to drag my feet.

Overall ,I am pleased with the result. The OAT on the ground was about 85 degrees and at 7,500 feet density altitude, it was about 67. At my normal cruise setting of 2,600 RPM, the temps stayed around 230 (red line is at 240F). It was only when I tried to go WOT the temps licked at 240. Also, my cylinder #2 has higher temps than the others.

This is a lot better than the carbon fiber sump and I think I should be able to get it a little better with some tweaking. I expect be covering that on the Q-200 Engine Group.