Why is LOP (lean of peak) controversial?

Matt Barrow wrote:

That's what a bunch here have been telling you. As well, is the problem
TATurbo (they did your's, Deakin's, mine, hundreds of others, but your's is
the anomaly.

I suspect you've been to the APS seminar, and you didn't notice something
wrong in your numbers? Then, too, it's not unheard of that an installation

Hey, I wasn't born with A&P knowledge and I have yet to go to an ABS BPPP
pilot or maintenance clinic. As you probably know, I am using the aircraft
to commute weekly to work and, thus far, I have failed to make time for
either, as work and family commitments took priority.

When the previous owner, who used to run an auto race team and perform his
own maintenance on both autos and airplanes, sung the praises of how cool
the cylinders ran on this aircraft, I assumed he knew what he was talking
about. This began my education in temperature management and set my
expectations.

No where have I read, prior to this thread, that temperatures above 300 but
below 350 degrees indicate a problem with the engine monitor. No where.

Initially, I agree that I reacted somewhat defensively here, but that has
changed and now I am definitely taking the responses here seriously by
contacting both TA Turbo and JPI to get this issue resolved.

What concerns me more than my newsgroup reputation is that, with incorrect
CHT readings, I have no idea where these cylinders are really operating.


--
Peter

Ray Andraka wrote:

There are two types of thermocouples used for EGTs.

Thanks, Ray. Just confirmed with the mechanic that the probes and wiring
are JPI, so now it seems to come down to the EDM-800 itself.

Awaiting JPIs response now.

--
Peter

karl gruber wrote:

Call TA...............see what they say.

FWIW, I just got off the phone with both TA Turbo and JPI.

TA Turbo stated that, while low of average, seeing 320 degrees as the
hottest CHT at 12,000 feet with WOT, 2500 RPMs and about 70 degrees LOP is
*not* unrealistic.

JPI's very overworked tech (I was on hold for one hour) gave me three tests
to ensure the unit is working correctly:

1) Confirm that CHT and EGT are registering ambient temperature when the
aircraft has been shut down for a day or so. Of course, my aircraft's
Tannis heater is plugged in today so this test will have to wait until I
fly to my destination this week and let it sit for a couple of days.

2) Pull the probe and submerge it in boiling water to confirm that it reads
212 degrees F.

3) Separate the probe from the wire and measure the probe's resistance. It
should register 1.3 to 2.0 olms.

I will start with number one this week, then perhaps move on to 2 and 3
next week when my aircraft goes in for a 50 hr oil change and other sundry
items.


--
Peter

"Peter R." wrote in message
...
Matt Barrow wrote:


No where have I read, prior to this thread, that temperatures above 300
but
below 350 degrees indicate a problem with the engine monitor. No where.

That's not the point except you're jumping ahead in the troubleshooting
sequence.

Initially, I agree that I reacted somewhat defensively here, but that has
changed and now I am definitely taking the responses here seriously by
contacting both TA Turbo and JPI to get this issue resolved.

What concerns me more than my newsgroup reputation is that, with incorrect
CHT readings, I have no idea where these cylinders are really operating.

The primary point is that your CHT reading were not just low, buy WAY low.
It takes some "getting to" to find if it's the JPI, the probes, the baffling
(do you have TA's "Liquid Air" baffles?), or any of a myriad potential
problems.

Here's an analogy: When my daughter bought her 2006 Honda Civic, she was
getting 28 miles a gallon instead of the more typical 38-40MPG. When we
took it back to the dealer, one of his questions asked of her was what she
thought the problem was. She responded that the problem is ..."it's getting
12-14 MPG less than it should." She didn't jump to conclusions.

Deakin's temps are higher than mine, but I'll run 75% and even up to 80% of
power, so being off 20 degrees is, to me, not a _shocker_.

You might just be one incredibly lucky pilot/owner. Certainly nothing wrong
with that.

On the other hand, those people that are pushing 400 for their CHT's should
be asking question if nothing else to find a better way to operate their
engines. In light of the number of Bo's that have top overhauls at 600 or so
hours, perhaps _they_ should be asking questions and doing some digging.

Now, if my Toyota Four Runner was getting 26 MPG, I'd be really happy, but
I'd be rather curious...or maybe _suspicious_ is the right word.

Hope yours is just a "happy engine".

--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO (MTJ)

Matt Barrow wrote:

That's not the point except you're jumping ahead in the troubleshooting
sequence.

Ok, but I was simply attempting to explain the reason for my "blissful"
ignorance. I didn't read John Deakin's articles the first time and think,
"Gee, my temperatures are so much lower than what he is cautioning against
that *my engine* must have some other explainable problem."

Instead, I simply read it and thought, "Hmm, looks like overheating
cylinders are not my problem."

The primary point is that your CHT reading were not just low, buy WAY low.

Again, TA Turbo didn't say to me on the phone today that my reported CHTs
were WAY low. "Lower than average, but not unbelievable" was the phrase
used.

It takes some "getting to" to find if it's the JPI, the probes, the baffling
(do you have TA's "Liquid Air" baffles?), or any of a myriad potential
problems.

The aircraft has the optional TA cheek plate louvers installed for summer
flying (as opposed to the shark-gill louvers, which is what I use in
winter), which provides a 10-20 degree lower CHT, and it has a TA optional
cooling baffling installed on the pilot's left of the cowl opening, which I
believe is to allow better airflow to the back cylinders.

In addition to the JPI tests pointed out elsewhere, I was also given
another pointer by TA Turbo. I need to check the probe wiring and compare
that with the setting in the JPI. If yellow/red wiring from the probes is
present, the JPI should be set to "K thermocouple." White/red is "J
thermocouple."

The TATurbo maintenance director said that an incorrect setting in the
EDM-800 would result in a minus 40 degree difference from actual CHT
reading. He then commented that if I see 320 degrees on hot day and this
error were present, he would still be impressed with an actual 360 degree
CHT.


--
Peter