Date:  10-31-2024

Number of Hours:  15

Manual Reference:  23

The problem was still waiting to be found….

I added a pointer for TDC and we confirmed all the spark plugs were firing and in the right order and the right place.

We confirmed yet again, the magnets that trigger the ignition were all correct. That’s the T1 S1 T2 S2 which light up when the flywheel magnets is in position over the pickup. All good.

Why was it running so rich that we keep getting backfires? I pulled the air intact apart to look for a rag I must have left in there.

No rag, clean as a whistle.

I rechecked the throttle position with what was happening down the back with that butterfly. Confirmed, I was getting throttle fully closed and open in sync with the throttle position.

Of course we had gone back to the wiring as well and with diagrams of pinouts at the big multi connectors we again checked everything and buzzed out the wiring. All was correct and connected as it should be.

I gave the new flywheel a lick of paint. The new bolts finally showed up from Texas along with the new insert. They were held up in quarantine by the wildlife people.  Who knew steel was a carrier of things dangerous to the native flora and fauna? I guess they needed to charge some storage fees.

The insert went in the freezer overnight and the licensed engine guy in the hangar made short work of installing it. I don’t think I’d have done so well. Everything is on a steep learning curve for me and there are times when its better not to have a couple of goes.

The bolts and the inserts were again very carefully cleaned. I chased the threads with a tap and die. This will be my new SOP (standard operating procedure) The prop went back on with anti-seize, yes my call,  and I had another go at trying to improve my lockwiring.

Through some friends we had made contact with a race car guy who was very experienced in ignition and fuel systems. Next came another wait for his availability.

THE RESOLUTION!!

Gary, (Mr Fuel and Timing) hadn’t done this sort of thing on airplanes and it took a bit to get him comfortable and explain we were only wanting him as a ‘consultant’ rather than walking away and expecting everything fixed. He knowns what a piston engine should be doing in terms of spark, fuel and air.

I had a print out of the Fuel Map and he gave it a good read. You can’t access all the numbers directly at the plane. You need to download the file and put it on a PC to view and then edit. The file is then uploaded back into the EFII system in the plane.  Here are the first few numbers of the original file.

He didn’t like what he saw. He felt that the settings for starting were overly rich and this was the problem. I am still not 100% on what I am seeing here. The big numbers at the higher MAP end really got his attention.

So rich for starting. Ok here are some of the numbers we ended up with as a quick new setup after the testing you see below. This was based of a fuel may we got from EFII as their standard. It was still a bit rich in my plane. We are going to need a good day of runs  at different RPM up to the higher ranges to set the whole map but the one above is ‘usable’ for low RPM work.

We did more testing with the new settings, plugs not connected and ignitions off of course. The numbers and cockpit indications were promising.

Time to try again. With an abundance of caution I didn’t even prime the engine. I remain concerned about the VERY expensive backfires. As I cranked Gary watched on checking the numbers. All seemed ok.

After a few more goes the engine was starting well with minimal throttle and idling quite low around 660rpm. Gary was monitoring the AFR (air/fuel ratio) very carefully on each start and we tweaked the low RPM section of the fuel table to the one I displayed earlier.

So the problem was found.  The supplied fuel map with the engine was rubbish. Given the log books say it has been previously run for 25hours, I have to conclude it was NOT with the supplied map I got and an error had been made. These things happen. The fault was in an unexpected place and took 3 months and several thousand dollars to find. Of course its easy to say, “Why didn’t you check this day 1?” A lot of people were involved and given the engine run history as presented, it took fresh eyes.

I always move forward. This is now in the past, gone and behind me.  The first taxi happened the next day.