Liking my Pponk but need some tips on getting the idle better.

Cold start is rough, #4 and #6 Cyl take a while to wake up, I add carb heat and increase rpm to help a bit, once running a bit and at 1,000 rpms it gets smoother, so no big deal here.

The one the I dont like is very low power or power off approaches, it is rough, carb heat or no carb heat, taxiing after landing also rough, unless I increase to 1000 rpm or higher.

On shut down we do have the 50 rpm increase before it quits.

Go through every piece of your intake system. Make sure the boots are all straight and the clamps are tight, a leak in one of these can cause what you're experiencing. Since you know which cylinders are problematic I would start there, that also meshes with an intake leak since it flows from back to front and your left two front cyls are giving you fits. You could also have a loose intake tube, though that's less likely since this isn't confined to a single cylinder. Still, it won't hurt to make sure those nuts are tight, especially on a new engine where things are heat cycling and settling in.

I would also recheck all spark plug wires are screwed in tight while you're there.

colopilot wrote:Go through every piece of your intake system. Make sure the boots are all straight and the clamps are tight, a leak in one of these can cause what you're experiencing. Since you know which cylinders are problematic I would start there, that also meshes with an intake leak since it flows from back to front and your left two front cyls are giving you fits. You could also have a loose intake tube, though that's less likely since this isn't confined to a single cylinder. Still, it won't hurt to make sure those nuts are tight, especially on a new engine where things are heat cycling and settling in.

I would also recheck all spark plug wires are screwed in tight while you're there.

+1. Had this exact issue with my Bonanza. Intake leaks are a bitch! Re-tighten everything!

Another vote for the same.

And while you have the cowl off, give the primer a few shots and check the lines for cracks / leaks. Doubtful this is the source of your problem, since you have multiple cylinders complaining, but far to easy to not check and rule out.

Virtually every cub driver I know gives each primer line a wiggle looking for loosened B nuts or cracks every time they check the oil (essentially every flight) I'm not sure I have ever seen a Cessna driver do the same?

Incidentally, both of these failure modes (intake hose and primer line failures) are extremely common on fresh rebuilds or new engines. We secure everything exactly where we think it needs to be, and then the engine comes to life with a shake, rattle, and roll, shrinking and growing with every thermal cycle and relocating everything to where IT wants things to be. Now we need to re secure. I know of 2 brand new O-340's and a brand new O-200 just off the top of my head to recently suffer similar failures.

I realize with your background I am preaching to the choir here... but sometimes the most obvious things are the ones we don't check.

Take care, Rob

FWIW, mine doesn't like to idle either but mine REALLY doesn't like to idle with the carb heat on.

They run rather rich by design, I find leaning a fair bit really helps smooth out the idle. I've modified my runup to leave the mixture rich (about an inch pulled out) before I test carb heat or idle.

I'm definitely not saying mine is running correctly, just that mine is running the same way. I've found a few times I've described situations to others, including my mechanic and Steve Knopp, and they say it is nothing to worry about, only to find out there was a problem all along.

Maybe try turning the idle screw in a little on the carb. It's what is feeding fuel at low rpm and might be too rich.

Much better now , adjusted the screw 1/4 of a turn in , re tightened all the clamps in the intake tubes.

Runs much much better now.

Thanks guys.