Lack of power in Cessna 172-R

Last summer we bought a 1997 160 HP Cessna 172-R. The test flight
(with 3 adults) went just fine.

Hi Chuck

Suggest you pull all of the plugs & examine them - I believe that you
will find at least some of them are black from running too rich.

I also suggest that you also post your question at:
http://www.cessnaowner.org/new/forum/forums.htm

There is a ton of Cessna knowledge there.

Tony


--

Tony Roberts
PP-ASEL
VFR OTT
Night
Almost Instrument
Cessna 172H C-GICE

Hi, Dan,

Thanks for your suggestions.

I leaned the mixture for the static runup and consequently got good
results. I did NOT lean before takeoff. Perhaps that is significant.

Chuck


On 12 Feb 2004 16:57:35 -0800, (Dan
Thomas) wrote:

"Gary" wrote in message ...


Also, there was a "burbling" sound from the exhaust.

Maybe loose baffle in muffler restricting the outlet. Could have
broken loose between the time you tried it and the time you took it
away.
Other things to check might be one mag retarded somewhat, perhaps
caused by a broken impulse coupling spring.
Did you try leaning the mixture a bit to see if there was better
RPM in the static runup?

Dan


Freedom Chuck - The Man of 1,000 Songs

see my website at: www.freedom-chuck.com

Hi, George,

Thanks again for your help. I'm going to ask my AME to check the fuel
injection system.

Chuck


On Fri, 13 Feb 2004 01:30:35 GMT, "G.R. Patterson III"
wrote:



Chuck wrote:

George Patterson, you say it's running way to rich. I was wondering
way you say this, but you just may be right. To correct this I

The "burbling" sound you report is typical of raw gas going through the engine
and igniting in the exhaust system. I'm not familiar with the injector system,
so I really can't help with troubleshooting. With a carbureted engine, you
could easily check this by leaning on the ground.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.


Freedom Chuck - The Man of 1,000 Songs

see my website at: www.freedom-chuck.com

Thanks for your suggestion, Tony,

I'll ask my AME to check the plugs, as well as the fuel injection
system. And I'll try the forum you suggested.

Chuck



On Fri, 13 Feb 2004 02:06:26 GMT, tony roberts
wrote:


Last summer we bought a 1997 160 HP Cessna 172-R. The test flight
(with 3 adults) went just fine.

Hi Chuck

Suggest you pull all of the plugs & examine them - I believe that you
will find at least some of them are black from running too rich.

I also suggest that you also post your question at:
http://www.cessnaowner.org/new/forum/forums.htm

There is a ton of Cessna knowledge there.

Tony


Freedom Chuck - The Man of 1,000 Songs

see my website at: www.freedom-chuck.com

On Fri, 13 Feb 2004, Chuck wrote:

Victor J. Osborne Jr., your question about fuel flow/pressure is
interesting. When starting you are supposed to advance the lean
control with the aux. fuel pump on to get about 3-5 gal/hr., then when
it starts, you turn off the aux. fuel pump. But once the engine
starts, I don't know what the fuel flow/pressure is. Do I read it on
the fuel flow gage?


You leave the pump on until after starting? My 172R POH says to shut the
pump off before starting. I only use the pump for priming and switching
tanks. I also make sure to lean back a few turns as soon as the engine
settles down.

--
Rick/JYO
remove 'nospam' to reply

fuel flow/pressure. I recently learned that some add-on fuel flow
transducers can restrict fuel flow, resulting in reduced flow (actually
pressure) to the injectors. i.e. you do not develop full power on take off.

Having said (?) that, I have no idea how you would check the fuel pressure
on a 172. W/o manifold pressure at sea level, I guess you w/b left w/
installing an aux. gauge for the test.

Thx, {|;-)

Victor J. (Jim) Osborne, Jr.



take off my shoes to reply

"Chuck" wrote in message
...
Hi, all,
First, I want to thank everyone who made suggestions.

Gary, a compression check was done on all cylinders and the
compression is fine. The power for a full-power static runup should be
2065 to 2165 with the mixture leaned for max rpm. The actual rpm is
about 2150.
I think this is the most significant thing said. There is no way that the
engine should give higher revs on the static check, than on the takeoff
roll, unless something is making a 'difference' between the configuration. I
see latter, that you say you lean for the power check, but not the take-off
roll. The obvious question at this point, is what altitude the field is at?.
If it is below perhaps 3000 feet, then the difference, together with the
noise reported really solidly implies that the injection is running rich at
it's default settings. If you are higher than this, then you should really
be considering leaning for takeoff.

snipped
Aaron Coolidge, your comment about the fuel injection is also
interesting. I will certainly ask our mechanic to check it (since the
plane is in for its annual anyways). I did not, however, notice loss
of power, but at minimum rpm (with the throttle full out) it does not
idle very well -- it feel like it's going to stop.
Rich...

George Patterson, you say it's running way to rich. I was wondering
way you say this, but you just may be right. To correct this I


Once again, thanks to everyone.

Chuck
I think George has hit the nail on the head.

Best Wishes

Chuck wrote in message . ..

I'll ask my AME to check the plugs, as well as the fuel injection
system. And I'll try the forum you suggested.

Wow, your AME must be pretty well-rounded. I don't think mine even
dabbles in mechanics. ;-)

On Thu, 12 Feb 2004 19:02:46 GMT, Chuck
wrote:

Hi, all,

All rpm indications were within spec (for static run-up, etc). When on
the takeoff roll, rpm was about 2100, which seemed low, but there is
no spec in the POH for rpm for the takeoff roll. The rpm went much
higher after we were cruising (2300 or so).

Also, there was a "burbling" sound from the exhaust.

The prop was removed, inspected and put back on (with pleanty of
scratch marks which weren't there before.


Are you sure they put the correct prop on the plane? I know some of
the new 172 series were produced with 160hp and others with 180hp.
Although you have to hope the mechanics did a better job - if you have
a 160hp it is possible they swapped props with a 180hp 172.

A cruise prop would drag down both the static RPM and climb
performance. On the other hand, you should notice a few mph
improvement in cruise (unless the prop is grossly wrong).

-Nathan

Chuck wrote:

it. OK it was hot but the book said we should be over a 50' obstacle
at about 1800' - we were not even close!

Hey Chuck,

Maybe those 1000 songs were weighing down the plane grin.



Michael Nickolas
www.studionineproductions.com