I guess you talk about the O-320 because of the diagram I shared of EGT/CHT, which I shared only for demonstration purposes regarding Lean of Peak not meaning hotter engine. In fact, it’s the opposite, lean of peak is quite cool. You will find basically exactly the same diagram for the O-360, in the link you shared. I couldn’t find one specifically for the IO-360, but I would be surprised if the injection technology has much to do with EGT and CHT curves. Would you say it’s different? Cheers!
No, I agree that graph looks the same as the one in the iO-360 manual. I’m not saying you are giving wrong numbers - I meant in general, people should be aware that the C172 they may have experience with IRL, or in other sims, is not necessarily the same as the more powerful & uprated version of the engine in the C172SP.
I do agree that there are some oddities, in the sim, and the post way up stating that Fuel flow initially rises when you start to lean the mixture does happen to me. However, I cant be sure that this is not the Axis I use being a bit jittery. The manuals and any notes I have seen do not show any upward 1Gal per hour blip of FFlow when leaning. I did just checking the results of leaning on FFlow & EGT, at sea level, but the needles were all over the shop on the ground, and nothing like the power curves on the graphs.
In the air, but below 1000ft, things looked different. I seem to be getting Peak EGT with 100% throttle, mixture at 50% lean, with FFlow pushing 16GPH, and “Best Economy” at about 30% mixture.
With the throttle of about 75%, EGT needle pointing to 3 O clock, and RPM on the nose by the book, at just under 2200, using 9 GPH of fuel. So not far off figures shown in the manual for this engine, apart from the fact that I had to lean the mixture to 30% at 700ft to get them.
PS I note with amusement that the C172 EGT red reference needle actually functions in the sim.
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Yeah I’m searching all over for this and can’t find it! Maybe it’s in the POH?
I’ve heard of instructors (and watched a YouTube video also) saying to lean mixture to the top of the fuel flow green arc above 3000feet when climbing.
I wasn’t ever taught this method though.
I’ve searched a bit and found that it means what the green arc normally means - normal range of operation. However, I found a different fuel flow gauge with different green “regions” for different phases of flight (climb, cruise…)
I would be very skeptical of assuming the green arc on the fuel flow of the C172 can be used for climb… I don’t want to say anyone is wrong, but I do like to see literature that confirms any such statements…
If you could point to one of those videos, I’d like to see it.
I don’t think 3000 is a good altitude to start leaning, when climbing. If we look at the performance tables, at 3000 feet the engine is still delivering a lot of power, and leaning at this point can get our engine dangerously hot… If we have a CHT gauge to confirm we’re not running too hot, then fine… but otherwise I would check the performance tables and see where max power is around 70% before I start leaning. Typically this is around 5000 feet…
It’s not the axis. I don’t have an axis for mixture, just use the mouse, and it happens also. It happens to everyone, it’s not hardware related.
This topic is all over the map in the sim. When you try to check the mixture setting on the ground, are you full throttle? If you are, then this is yet another bug… behavior of the engine and mixture should have nothing to do if you’re on the ground or air…
Anyway, personally, I don’t expect the numbers to match up exactly with… well, anything… I’m just expecting the “behavior” to be realistic…
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Yeah, the axis mention was just there because I cant be arsed to test another setup 
Throttle setting: Yes - On the ground, at EGKA, elevation about 7ft, at 100% throttle. in the air at around 700ft at 75%. I used to work on these engines (many moons ago & not on a C172 though), and I don’t recall this sort of behaviour.
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That’s a fine concern, but the C172 POH calls for leaning at 3,000 feet, so I wouldn’t just ignore that. And I think the “lean to the green arc” method was an approximate method that keeps the engine slightly over rich in the climb.
This guy filmed his entire PPL lessons from start to finish, and the instructor is definitely not the best instructor ever, in fact quite the opposite, but I recall in one or some of the earlier videos the instructor is asking him to lean to the top of the green arc. Sorry I can’t be more specific, it was years ago I saw this. From memory it’s one of the earlier lessons where he’s learning the pattern (if you can be bothered to watch through them to find it)
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Just a message to bring this thread up to get more votes as this issue is still there.
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I’ve set up my hardware controller so the mixture does go up to 91% and not higher. That’s a stupid workaround, but now as long as I’m not at an altitude airfield, I know that for take off/landing, I have max fuel flow & power with my mixture slammed forward, and I don’t have to lower my “eyes” to the cockpit to visually check the lever position.
Now my real problem is the G58 (same for the SR22 I hear ?) where the mixture lever has zero effect (except for killing the engine when fully lean). That’s super annoying that they felt this was release-ready.
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Everyone in this thread is more knowledgeable on the subject, so a quick question. I assume this isn’t how it should be in real life. I’m only flying the 152, and most of the time below 3000. But once in a while when venturing higher I do lean the mixture according to the POH. I get the rise in RPM but to get to the 25-50rpm drop that I’m looking for per the POH it seems I need to lean the mixture way more than necessary. Seems like at 3500 feet I’m having to lean to at least 50% before getting a drop in the RPM.
That’s the way it works since (at least) FSX and it’s not the way it works IRL. I’ve switched to automixture a long time ago because it’s more realistic at low/medium altitudes.
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current mixture behavior is complelty b…s…t … so many threads about, so many issues because of it, so many confusion, so many users which report engine goes off, no power, and and and…
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(Note. I’m not a pilot, but love the sim)
I’ve been flying a 172 over the Sierras from KFAT to KBIH (Fresno to Bishop CA) which requires an altitude of 12k MSL and the 172 just bogs down between 9K and 10K MSL with the auto-mix on, the plane stops climbing. I’ve made it over once by sheer luck literally flying down canyons but I thought the 172 was icing up or something, and it was a fight to keep the nose up above 10,000 ft. This problem with the fuel mix seems to get worse as I stay in high altitude flight plans. My first one, from Fresno to Furnace Creek in Death Valley took me close to Mt. Whitney and I didn’t seem to have any problems maintaining 12k + MSL. I think it was simple beginners luck, really.
So, after reading this I turned off the auto-mix and tried a fuel mix around 50% to get some altitude, taking off from Bishop at 4540 MSL and getting to 11K was much easier. Now I’ll have to read up on how the mix works to find the sweet spot to make it back over or though these mountains. Its a steep climb out of Bishop going west.
Before I tried this challenge, I was just hopping from one coastal airport to another, no altitude greater than 5000 MSL and had no issues with the 172.
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What do you mean 25-50rpm drop as per the POH? Don’t you mean a 50ºF drop on the EGT gauge, on the rich side? I’ve never seen a POH asking for an RPM drop.
Cheers.
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Why would we waste efforts on a topic with less votes? Let’s unite here!
Because that topic is the one that gets read out in the Q&A tomorrow if it gets enough votes, ensuring the developers are 100% aware of the issue… please vote on it. There’s a reason I created it and linked it.
Once again, please vote on this thread so it gets read out tomorrow 
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