Trying to figure out leaning, etc.

[Godfather]

12 minutes ago, chrixxer said:

I'm still finding two peaks with the EGT (while CHT never seems to move, always right around 380).

I've got a request out for a quote for a CGR-30P, while the rebate's on. I find JPI really user-unfriendly (company and equipment alike)...

 

What do you mean by two peaks?  Does it reach a peak temp twice with a drop in the middle?

[chrixxer]

27 minutes ago, Godfather said:

What do you mean by two peaks?  Does it reach a peak temp twice with a drop in the middle?

Yeah, I think I posted about it above. What happens is, I pull back slowly on the mixture and watch the EGTs climb. At a certain point (usually around 1325-50 or so), they start to decrease. I interpret that as being lean of peak. I start to slowly (rotate) enrichen, and the temp goes back up and then starts coming down. After about 45-50 degrees or so, it climbs again (still enrichening), back up to ~1350, then decreases again. I usually settle somewhere in the 1215-1250 range. 

Someone with more Mooney time than I have told me: “I often see that second peak that you described. In fact, we spent a lot of time adapting [redacted] to account for it. My theory is that the double peak is because the fuel servo is trying to adjust to the change in mass airflow at that same point due to the power reduction near peak.  In addition, it is due to the lag time in the EGT probes and the slight overshoot of peak and then back through it again.”

IDK. It’s definitely not quite as plug-and-play as the Arrow I’m used to. Significantly faster, though.

(Mine also burbles a bit and occasionally 'pops' at idle, too, which I'm not used to with the IO-360. At cruise it's like a sewing machine, but on the ground or pulled back on approach, it's a little disconcerting. Next time she's in the hands of an A&P I'm going to have it looked at. 40 hours like that, though, and she's never died or anything, just sounds (to me) odd.)

[HRM]

On 7/6/2017 at 4:50 PM, Bob_Belville said:

Here's the sort of panel a '66E deserves:

Shoot, here's the monitor it demands 

 

[chrixxer]

39 minutes ago, HRM said:

Shoot, here's the monitor it demands 

 

I wish... a bit outside my CB budget, but I can dream ...

[carusoam]

Chris,

It would be great if you could share your data...

If the twin peaks were real, you would find other people posting similar hard facts, replete with graphs.

My biggest concern is you may be describing an oddity that should be looked into...

Or maybe it is just a misunderstanding of what you are seeing... in other words, you may be leaning and enrichening at a pace that your system can't handle.  

Leaning too fast, the peak occurs long before you see it on the instrument.  Trying to find it again by enrichening, the peak appears in a different place...

ya know what I mean?

Many older JPIs got slow acting sensors.  Great for longevity, but terrible for leaning real time.

The real peak doesn't move.  Once you have found it, you can slowly adjust mixture to know exactly where it is.

 

If you try to lean slowly from full rich, to see the perfect peak, you will be doing this step for many many minutes.

Once you know roughly where the peak is, lean or enrichen slowly until it peaks and comes down...

 

Expect only one peak.  Speed at which you change the mixture has to match the speed that TCs can actually operate.

How does that sound?

PP thoughts only, not an instrument tech....

Best regards,

-a-

[HRM]

On 7/10/2017 at 10:38 PM, carusoam said:

It would be great if you could share your data...

1:50  flight/warm day/KEDC->KBPT via I-10 corridor through Houston.