Manifold restrictor plugged with carbon

After 500 hours on my Superior IO360, my manifold pressure gage (cylinder #3 port) quit responding to engine power settings. This is what I found:



Is this normal? I cleaned it with some MEK and safetywire. All is working normally again...
Engine is dual EI and fuel injected.


Don

My 10-Friend found black goo in his line, it was near solid when cool, then as it warmed, the MAP would work ok. ~200 hrs. The goo is heavy ends from fuel, like pitch. It could easily harden with time.

Was your hose/line clear?

I imagine this could be bad for a electronic ignition engine with MAP for timing.

Planecrazy232 said:

I imagine this could be bad for a electronic ignition engine with MAP for timing.

Click to expand...

?. I had this as well with a line going to my map sensor for the
ignition. I moved the pick-up to the carburetor base, eliminating
the problem and gaining a much smoother signal in the process.
The engine actually seems to run a bit better (I think). Thanks,
Allan...

PerfTech said:

…. I had this as well with a line going to my map sensor for the
ignition. I moved the pick-up to the carburetor base, eliminating
the problem and gaining a much smoother signal in the process.
The engine actually seems to run a bit better (I think). Thanks,
Allan...

Click to expand...

I did the same to avoid this problem. There is a lot of reversion in the intake port area and you should expect carbon build up there.

Larry

Unfortunately, this is on a fuel injected engine, and there is no port that I'm aware of near the servo. It took 10 years for this to plug up and the MP readout is a luxury for me with a fixed pitch prop, so I might just have to live with periodic cleaning.

It does affect the spark advance on my electronic ignitions, but that just means they will operate at 0 degrees and shouldn't be a flight safety issue.

It just seemed odd that I would see this concrete-like build-up on the upstream side of the combustion chamber and I was worried that I had a sticking intake. The rebound theory seems to be more likely to me.

Thanks!
Don