TSIO360GB running rough at low RPM

[Emmet]

Hi,

the TSIO360GB in my M20K runs pretty rough at RPMs below 1300. If I go higher it runs perfectly smooth.

Has anybody else experienced such behavior. Any idea where it might come from ?

Emmet

[Parker_Woodruff]

The GB was a much rougher engine near idle.  Original engine still?

[Emmet]

It was overhauled once (and unfortunately not vonverted to LB) and has about 1000h now.

[Parker_Woodruff]

New problem or has this roughness always been the case for your engine?

[Emmet]

... since I bought it 1/2 year ago - so I really dont't know ...

[Piloto]

Does the engine smooth out at idle when the mixture is gradually pull out? If it does you need to adjust the idle mixture.

José  

[Piloto]

Also check for air leaks on the intake pipes. This would be reflected on a cylinder having a higher EGT reading than the others at idle.

José 

[Emmet]

The idle mixture has been adjsuted at the last annual in march...

But I will try to do the lean test the next weekend.

The air leak approach sounds promising - even if I don't have a good idea how to locate it ...

[jlunseth]

I have the LB not the GB, but pretty much the same experience.  The engine is set up fairly rich.  I lean to 100-125 ROP at cruise, and then I just leave the mixture knob there when I descend and land.  The engine does much better at idle on a leaned out mixture.  Of course, if you are going to power up for some reason you need to push the mixture in before the MP.  It is not perfect, but better than running it at full rich at a low power setting. 

[Chuck]

I just bought a 20k over the winter with the GB engine - had exactly the same experience - kind of sputters at 12-1300 and below. I find that leaning back the mixture with a few turns on the vernier smooths it out.

[opie]

I have a 79 230K with a GB.  It runs like Harley below 11-1200 and then smooths out above that.  It helps to aggressivly lean at idle.  Generally speaking the birds are too rich at idle anyway which leads to spark plug fouling. 

[Emmet]

The leaning helped - not really what I wished but it looks like I have to live with it ....

Thanks guys !