Aborted takeoff, engine not producing full power

[Johann]

Why wouldn't you simply push it back in?

Funny you ask. Once I was holding short for longer than usual, so to kill time (and the other good reasons to do this for) I started leaning.
I went too far and the engine started stumbling. It seemed like it was going to die, but just pushing back in made it go back to normal.

Don't get me wrong, I would do this, it's just that I would first do it without messing with anything first, and then depending on how that went maybe I'd do the mixture test.
I just don't see myself doing it soon, as I won't get the chance.

 

[Tom-D]

A quick glance to see what it's reading while you roll is one thing,

What else would it take? an hour study?

 

[TMetzinger]

Most FBO's know that trick, and use oil pressure switches rather than the master to activate the Hobbs meter.

Clearly what's needed are oil pressure and temperature switches in series, so you don't pay until the engine is operating at a decent temp. And then put up a light that's labelled "You are now paying for the airplane. Go fly".

 

[Henning]

Most retracts I have rented had the Hobbs on the squat switch.

 

[Johann]

I went flying again so I had the chance to do some tests.

I didn't fly the same plane, but it's "sister" plane. Same model, same year, same engine.

After the usual run up, I did a full power run up and magneto check to see the drop. It didn't go outside the green, it dropped probably 100 RPM or so on one magneto, so I guess that rules it out (unless the other one had something wrong in some spark plug, but that would be a stretch as it would have been caught later).
The oil was not in the green when I did the full power run up, so it leaves that out of the question as well.

It wasn't as cold (although still cold), and it was the first flight of the day for the plane.

My instructor was at the FBO and I mentioned what happened. He said it could have been the tach, as some mentioned here.

The throttle on this plane felt normal (not nearly as hard as the other one that day). Also, there's a metal stop for the throttle (where the friction lock goes). The stop for this plane is half as short as the other one, which seemed weird, but if the other one had a stop that didn't let it go to full power I'm sure someone would have noticed by now, specially since it has been flying apparently with no issues these past few days.

All things considered, I would guess the cold or some ice did something to the throttle, or the tach.