Superior IO360 rough running

[Rockyjs]

I have a new never flown Superior horizontal induction motor with Precision FI. The FI AD has been complied with. I'll contact the builder tomorrow, but I'm interested what some of the motorheads think might be my problem. Engine starts right up cold or hot. It idles a little rough, but the # 3 cylinder is about 300 degrees cooler than the rest most of the time and during a mag check the drop is about 120-130 on each mag and sounds like a machine gun. CHT on # 3 is the warmest, but only by about 25 degrees. I get some afterfire popping noises. The bottom plug seems a little wet, but not really fouled. I've swapped plugs from top to bottom with no positive results. We pulled the fuel nozzle on # 3 and cleaned it, but I haven't run it yet. I will do a flow check on the divider tomorrow. Is this a lean burning cylinder? It's disappointing since I just got the Airworthiness Certificate on the bird. Any help out there?

Thanks
Rocky

[mannanj]

Just a suggestion...........may not help, but have you tried swapping BOTH the top and bottom plugs between #1 and #3 cyls. to see if the temperature variation follows the plugs? Swapping plugs top to bottom wouldn't help if you have a bad plug.

[flyeyes]

Originally Posted by Rockyjs

(snip)I get some afterfire popping noises.(snip) I've swapped plugs from top to bottom with no positive results. (snip) Any help out there?

Thanks
Rocky

This may sound dumb, but I'd double check the mag timing and make real sure the plug wires all go to the right places.

[Rockyjs]

Mannan, Thanks I'll swap the plugs to # 1 tomorrow.

James, we did recheck the mag timing today, they are right on.

[Aden Rich]

I would also pull the injection nozzles and make sure you have the right size nozzles and nothing is plugged. I believe .028 size hole is correct for the Lycoming but a quick call to AFP would settle that. Also, get four baby jars and pull all of the lines to the injection nozzles. Put the lines into the jars and then turn on the boost pump. Run for a few seconds. Check the level in the jars on a level bench. They should all have the same level in them, meaning there is not blockage coming from the flow divider.

[Geico266]

Have you done a compression check on the engine? My guess is the plugs or wires.

Keep us informed.

[David-aviator]

Originally Posted by Rockyjs

I have a new never flown Superior horizontal induction motor with Precision FI. The FI AD has been complied with. I'll contact the builder tomorrow, but I'm interested what some of the motorheads think might be my problem. Engine starts right up cold or hot. It idles a little rough, but the # 3 cylinder is about 300 degrees cooler than the rest most of the time and during a mag check the drop is about 120-130 on each mag and sounds like a machine gun. CHT on # 3 is the warmest, but only by about 25 degrees. I get some afterfire popping noises. The bottom plug seems a little wet, but not really fouled. I've swapped plugs from top to bottom with no positive results. We pulled the fuel nozzle on # 3 and cleaned it, but I haven't run it yet. I will do a flow check on the divider tomorrow. Is this a lean burning cylinder? It's disappointing since I just got the Airworthiness Certificate on the bird. Any help out there?

Thanks
Rocky

Rocky,

The message is a bit confusing....one line says #3 is about 300 degrees cooler and the next says it is the warmest but only by about 25 degrees. A 25 degrees spread is no big deal at this stage but 300 is.

The after fire popping noise is ignition and unburned fuel on the exhaust stroke. Something would appear to be screwed up. Are you sure the aircraft has mags or perhaps one side an electronic ignition system? Some electronic systems, like Jeff Rose, have the "wasted" ignition fire on the exhaust stroke which can result in a popping noise at low power.

When you say "contact the builder tomorrow", that must mean this machine is not of your making. What does he have to say about the situation?

[mahlon_r]

Originally Posted by Rockyjs

I have a new never flown Superior horizontal induction motor with Precision FI. The FI AD has been complied with. I'll contact the builder tomorrow, but I'm interested what some of the motorheads think might be my problem. Engine starts right up cold or hot. It idles a little rough, but the # 3 cylinder is about 300 degrees cooler than the rest most of the time and during a mag check the drop is about 120-130 on each mag and sounds like a machine gun. CHT on # 3 is the warmest, but only by about 25 degrees. I get some afterfire popping noises. The bottom plug seems a little wet, but not really fouled. I've swapped plugs from top to bottom with no positive results. We pulled the fuel nozzle on # 3 and cleaned it, but I haven't run it yet. I will do a flow check on the divider tomorrow. Is this a lean burning cylinder? It's disappointing since I just got the Airworthiness Certificate on the bird. Any help out there?

Thanks
Rocky

Did cleaning the nozzle fix it?
Good Luck,
Mahlon

[andyrv]

I have a new Superior IO-360 with Precision vertical induction with a similar issue except it is #2 cylinder.

Mag Timing correct
Compression 78/80
Pulled all 4 nozzles - all clean.
Top plugs (EI) clean
Same behavior running only EI or only MAG
4 jars under lines at the nozzle, boost pump - equal fuel from divider


Engine runs smooth and #2 EGT comes up during a 1500 rpm runup but only with serious leaning with mixuture control. Any move towards full rich and #2 EGT dives with engine roughness (my guess is #2 is fouled/close to fouled and enrichment completes the process).

All bottom plugs were black/wet but didn't appear to be fouled.

My current thought is that the injection servo is delivering too much fuel at full rich as soon as I leave the idle setting range (anything outside idle range is non user-adjustable). I put new plugs in bottom tonight to see if the #2 problem goes away for now. I'll run it in the morning.

Andy