leaning during taxi?

[gsengle]

I've heard a number of people talking about leaning out the engine during taxi to prevent fouled plugs.  On my IO550, there is a lot of fuel flowing at full rich, and I've had a fouled plug or two so this seems to be good advice.  Any advice on how far to lean?  Technique?

 

Greg

[wishboneash]

Lean it aggressively to the point it runs rough. When you apply power during run-up, the engine will stumble and you will realise you have to enrichen it.

[1964-M20E]

I lean to peak RPM starting from about 1100 RPMs fro my IO360. Sometimes I'm so lean the engine stumbles when I advance the throttle to taxi. The good thing is it makes sure I have to go rich for take off.

[Hank]

I generally pull the red lever at least halfway back. Long as I can taxi without stumbling, it's good. Rarely have a fouled plug anymore, even last weekend at RDU with extended-range taxiing and one set of progressive instructions [i'd guess 10 minutes from engine start to run up]. Run up reminds you quickly that the mixture isn't in.

[jlunseth]

The way to do this is to lean to idle rise.  If you set the RPM's at somewhere around 11-1200 and slowly pull the mixture knob out you will notice that the RPM's rise approximately 75 rpm and then start to fall off.  At idle, at least in my plane, once you reach the fall off point you are not very far away from having the engine stop because of fuel starvation, although it probably does no harm to run the engine that lean at power settings that low.  So lean the mixture until the RPM's start to fall off and then bring it back to peak idle rise. 

 

As a footnote, idle rise happens even with a constant speed prop since the low power settings have the prop against the stop - the engine is behaving like a fixed prop engine. 

[Bartman]

600 hours on my IO360 with agressive leaning on the ground and flying LOP since I have owned her, and never a fouled plug. I highly recommend leaning beyond peak RPM as soon as she warms up for a few seconds. Can't take off too lean as it will just stumble

[Joe Zuffoletto]

Can't resist... I taxi at 50 LOP. 

[Bob_Belville]

I lean while on the ground now but since I replaced Champion massives with Tempest fine wire plugs I really doubt it matters that much. (I started flying Mooneys in '69 and I do not recall and prevailing wisdom to lean anywhere below 5000'.

[fantom]

I lean aggressively on the ground.....almost always to the right.

[FlyDave]

I lean aggressively on the ground.....almost always to the right.

Nyuk Nyuk Nyuk.....Soitenly!

 

(sorry, I couldn't resist)

[carusoam]

I thought we were avoiding politics here???

Yous guys ah soo funny!

-a-

[Bob_Belville]

To be more precise, I lean the mixture of the IO360 A1a whenever the M20E to which the engine is attached is on the ground... 

 

Geez...

[Hank]

Good point, Bob. I lean my O-360-A1D when on the ground and off the runway. Halfway or more, never watched for an RPM rise, and I generally prefer 1000 RPM.

[fantom]

I thought we were avoiding politics here??? -a-

What are you talking about....doesn't everyone have to lean to get to the RED knob?

[Hank]

Nah, some of us are tall . . . .

[FloridaMan]

I had issues with fouled plugs and switched to the extended electrode plugs and the issue went away. Even so, sometimes I'll still lean on the ground and I like to lean as aggressively as possible so the engine won't run up if for some reason I forget the mixture. 

[Earl]

As with the others I lean aggressively when I taxi.  I also have an EDM-730 and am lean during my runup.  Just look for the rise in temps when I check mags which is a much better diagnostic of mag performance than the RPM drop.  Not only tells me if I have a mag problem but also can pinpoint blocked injectors, bad plugs, etc.

[FloridaMan]

As with the others I lean aggressively when I taxi.  I also have an EDM-730 and am lean during my runup.  Just look for the rise in temps when I check mags which is a much better diagnostic of mag performance than the RPM drop.  Not only tells me if I have a mag problem but also can pinpoint blocked injectors, bad plugs, etc.

 

I don't know about Continental, but I believe that Lycoming released a bulletin suggesting that watching EGTs climb with the mag check is now the preferred way. 

[Dale]

I also lean for taxi. I read an earlier thread on Mooneyspace a couple of years ago and I started leaning until the engine rpm picked up and the roughness in the engine went away. I watch my fuel flow meter and essentially without leaning I am around 2.4 gph and when I lean the fuel flow is around 1.8 gph and the engine rpm picks up and the engine smooths out nicely. To avoid attempting to take off without enriching the mixture to full for takeoff I take a small binder clip used to hold papers together and I put it on the throttle rod just in front of the throttle knob when I lean the mixture for taxi. With the clip in place you can still do your engine run up but you can't advance the throttle forward any further for takeoff. With the clip in place you can't move the throttle forward enough to take off. I had the unpleasant experience once of trying to takeoff without the mixture set to full rich and although the engine does start to sputter, I didn't want to get to that point to remember to richen the mixture, so I came up with the clip idea, which so far has worked beautifully.

[aaronk25]

Lol.....people still scared of the red knob. Lean it until it barely runs and you know your doing it right if you have to add a touch of power to climb a slope and it coughs and wants to quit. Then slide the mix forward just enough so it will allow enough rpm to get up the hill then pull it back.

Keep all the hardware in the cylinder clean.

[jlunseth]

Yeah that does not work on all Mooneys.  It may work on four cylinder NA Lyc, but on the turbo's, especially the K's, you may be running on four cylinders out of six at low idle, the other two being too far down the induction tube to get enough fuel to fire.  If I lean until it barely runs, it will barely run for a minute or two and then quit from starvation.  It needs to be leaned to idle rise and not further.