Backfire and burble trouble.

[TOAD]

I am having real trouble with my IO-360 engine burbling and making all sorts of testosterone exhaust type noise as I throttle back. I have to make this verrrrry slowly to keep it from making all kinds of noise. What should I be looking for and how do I fix it?

I have been advised that this could be air in the exhaust, so I borrowed a smoke generating exhaust leak detection tool. There is quite a bit if leakage between the short stack and the main crossover pipes. How do I stop this? Should I have the pipes welded or can I tape them up somehow, at least for a test. Welds seem to be a bad idea but may be the answer. Opinions? Thoughts? Help!!!

Are there other places I should also be looking for the source of the problem?

I am having a hard time sneaking the plane in and out of the airport without people calling the fire and police about the airplane that is inevitably gonna crash with engine failure.

[scard]

Are you talking about something more than the normal exhaust popping noise when the throttle is almost or fully closed?

[rich]

This has been covered before.Try this link and see if this is what your talking about. If not you have a problem.
Rich
http://www.vansairforce.com/communit...+throttle+back

[TOAD]

Aerosport O-360-B1B, Lightspeed Ignition, Airflow Performance FI, Vetterman Crossover 4-into-2 exhaust.

I never cut to idle quickly. I start several miles out before pattern and just nudge it out or the popcorn machine will kick in. It will pop just on a taxi also unless I give it some throttle to quite it down.

Thanks for the replys. I had bought into the just live with it until my neighbor with the same engine claimed no noise from his plane. Could he be pulling my leg?

I will look into what he is using for an exaust system. I think this popping is excessive for my plane. I can look into mixture at idle also. Could changing the exaust system to another style fix the problem?

[Jamie]

Originally Posted by TOAD

It will pop just on a taxi also unless I give it some throttle to quite it down.

This is certainly not the norm for RVs. I have never seen one pop while taxiing and mine doesn't do it (although it does in flight if cutting the throttle quickly). Sounds like you've got something else going on.

[DEWATSON]

TOAD,

I replaced the seals around the intake tubes into the sump and mine stopped popping. I checked everything under the sun to no avail. When I replaced the intake tube seals, it became a different engine. Good luck.

[Gary 40274]

Excessive lean mixture at idle can cause popping on the ground. To check for proper mixture slowly lean the mixture at idle and you should get a 50 to 75 RPM rise just before idle cut off. If you don't I suspect you are running lean and need to enrichen the idle setting. Is this Carb or injected?

Gary Specketer

[TOAD]

This is an injected engine. I am wondering if the AirFlow performance induction system is different from other injection systems or plays into the issue in some way.

Now that I am searching my memory I am convinced that the engine used to run much better and that things are getting worse. I will head out to the hangar as soon as I get home tonight to look into mixture and look for a leak on the induction side. I suspect the exhaust is as tight as it was on day one. All my efforts were directed to exhaust and I will switch to other areas because I do not see anything that looks significant there.

[RetiredRacer]

It sounds like you have already checked for leaks around the exhaust, but anywhere it can suck in air (exhaust to cylinder head, exhaust probe, a pin hole in a weld etc) will cause it to pop in the exhaust pipe.

[rich]

Toad,
You might want to check the exhaust and intake bolts where they attach to the cylinders heads. The first couple hundred hours everything loosens up.
I had a blue streak(gas) leaking from the top of #3 intake. The gaskets were shot after 500 hrs.I check mine at annual and some need to be re-torqued.
Hope this helps.
Rich