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Anyone with IO-320 and engine monitor?

F

flyinhood

Well Known Member
We are starting to diagnose a fuel stumble. It looks like my idle power MP is 12-14 inches at around 750 RPM. So far no luck with finding any intake leaks.

Does anyone have data on a normal MP at idle on a 160 hp IO-320?

Thanks in advance.

Hoody
 
IO 320 B1A with Dual Lightspeed and AirFlow Performance injection, Denso plugs:
9.9" @ 740
OAT 19.9 C

Hope this helps,
David
 
I adjust idle mixture via the lowest MAP approach. I vaguely remember my best map being in the low 10's for my IO-320.

Intake leaks are not the only thing that will reduce maximum vacuum levels at idle.

Larry
 
Manifold Pressure at Density Altitude of 2,100 feet is 14 Inches at 820 RPM

Usually starts cold with out much problem. But, after landing very rough idle after engine is warm. Acts like vapor lock after landing and very hard to hot start

I have a 160 hp IO-320 with AFP, 1 P-mag, 1 slick.
 
flyinhood said:
Manifold Pressure at Density Altitude of 2,100 feet is 14 Inches at 820 RPM

Usually starts cold with out much problem. But, after landing very rough idle after engine is warm. Acts like vapor lock after landing and very hard to hot start
Click to expand...

14" seems high if the rings are in good shape with no intake leaks. Your symptoms point to a rich idle mixture. Cold engines require a richer mixture and explains why your engine idles well when cold. When properly adjusted (done with a warm engine), your slow idle should be a tad rough when cold (we don't have chokes, so adjust for warm and deal with a rough running idle when cold), requiring a higher RPM to smooth out.

Larry
 
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I have an IO-320 and it also has a rough idle, the only thing that improves it a bit is to aggressively lean it. Runs great at higher power settings but it's no sweet heart at idle.
 
What propellor?

flyinhood said:
We are starting to diagnose a fuel stumble. It looks like my idle power MP is 12-14 inches at around 750 RPM. So far no luck with finding any intake leaks.

Does anyone have data on a normal MP at idle on a 160 hp IO-320?

Thanks in advance.

Hoody
Click to expand...

If you have a light weight prop- FP wood or composite, low RPM will not be as smooth no matter how flawless the fuel, intake and spark set up is, VS a heavier metal prop or with a balancer ring / inertial ring. I have not read this entire thread, so this might have been brought to the discussion already.
 
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