Manifold pressure dropping - help please

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uksfpred
Posts: 52
Joined: Mon Dec 19, 2016 3:18 pm

Manifold pressure dropping - help please

Post by uksfpred »

Hi guys, I love flying the A36 Bonanza, however I seem to not be understanding something when it comes to the Manifold pressure dropping.

I thought this was mixture related to do with altitude from what I have read in other forums, yet today I was as low as 2500ft and i couldnt reach the 5000ft requested by ATC, in fact i couldn't get much over 2500ft before my engine sounded like it was dying, i would drop to about 1000ft and then it would come back to life.

I have Pitot and prop deice on, i usually adjust the mixture when i gain altitude i know you should run lean when higher. but i don't know whats causing this at low altitude. outside temp is around -1 and cloud is low.

What am i suppose to do in able to gain altitude :(

Could anyone please shed some light on this. .


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Pop
Posts: 325
Joined: Sun Jul 29, 2012 8:20 pm

Re: Manifold pressure dropping - help please

Post by Pop »

I have several hours in the A36, great a/c. Looking at your gauges, MAP ="0", with EGT very low. fuel pressure is "0"??? Try turning on the "aux fuel pump". Mixture should be "full rich" in climb, only lean when at level altitude. Then lean until EGT maxs out the rich to 10 degrees cooler.
I assume you had max throttle in the pic.
uksfpred
Posts: 52
Joined: Mon Dec 19, 2016 3:18 pm

Re: Manifold pressure dropping - help please

Post by uksfpred »

yes max throttle and fully rich :/
Pop
Posts: 325
Joined: Sun Jul 29, 2012 8:20 pm

Re: Manifold pressure dropping - help please

Post by Pop »

I can get the same gauges as you with the mixture idle cutoff and throttle closed. Check the settings in the controls section and in your throttle itself, what kind do you have?
uksfpred
Posts: 52
Joined: Mon Dec 19, 2016 3:18 pm

Re: Manifold pressure dropping - help please

Post by uksfpred »

This happens to me quite often I'm surprised more people haven't commented on this
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WarpD
Posts: 1469
Joined: Mon Feb 14, 2011 5:29 am

Re: Manifold pressure dropping - help please

Post by WarpD »

Ensure sensitivity for any axis on throttle/mixture/prop are always at maximum. In fact, I strongly recommend any joystick axis assigned have it's sensitivity set to max.
Ed Wilson
Senior Developer
Mindstar Aviation
uksfpred
Posts: 52
Joined: Mon Dec 19, 2016 3:18 pm

Re: Manifold pressure dropping - help please

Post by uksfpred »

Im not really sure i understand this answer.

Are you suggesting the mixture/prop has to be in an exact position in order for the pressure to not drop ?

I understand the need to lean the mixture more and more as you gain altitude and for the most part this is fine.

But it seems in low cloud or poor weather (this could be coincidence) that even at altitudes as low as 2000FT i can lose pressure and then power until i descend without choice, to a lesser altitude then it suddenly picks up again.

I'm not suggesting this is unrealistic, I'm saying I dont understand what I'm doing wrong or how to correct it. Ive been close to crashing into the ocean before now before the power finally picks up. and with FS Passengers pilot i have hundreds of hours with and instant record on that was scary times!

I'm going to have to make a video i think.
fastica
Posts: 1
Joined: Sun Apr 16, 2017 4:19 am

Re: Manifold pressure dropping - help please

Post by fastica »

I just had the exact same problem. I was starting a trip across NA and crashed on my 1st flight. I started the flight in IFR conditions with clouds at 200ft and below 0 C temperatures. Climbing was ok and then suddenly I lost all power and with the help of 0 visibility I crashed.

I just discovered that it's a bug from FSX inherited by Prepar3D, where the sim believes the game has carburetor although it's a fuel injection plane. Pressing the H (carb heat) key solves this problem.
Mike Schroeter
Lockheed Martin
Posts: 341
Joined: Thu Jan 12, 2012 7:05 pm

Re: Manifold pressure dropping - help please

Post by Mike Schroeter »

"H" is listed as both Carburetor Heat and Anti-Ice. In the fuel injected model, "anti-ice" opens an alternate air intake, as the primary intake can ice up in appropriate conditions on some aircraft. I'm not sure if the Bonanza has this particular controls or what method it mitigates this type of icing.
danielg
Posts: 114
Joined: Tue Jun 03, 2014 1:26 am

Re: Manifold pressure dropping - help please

Post by danielg »

I did a full videotutorial explaining for the Bonanza A36:

- The manifold pressure gauge
- What is the EGT peak
- How to calculate the EGT peak
- How to fly rich or lean according the calculated EGT peak
- How to understand the CRUISE PERFORMANCES TABLES
- When to fly LEAN or RICH according the cruise performances tables

The part you like is here (click to follow the link):
https://youtu.be/JdwFINXPReE?t=1h33m39s

In the video I describe a full flight from Madrid to Ibiza, following real time charts and procedures and real check lists for this aircraft, also with a VOR/DME approach, following real charts ;)
lonewulf47
Posts: 26
Joined: Sat Apr 14, 2012 6:56 am

Re: Manifold pressure dropping - help please

Post by lonewulf47 »

This is - unfortunately - standard behaviour of P3D/FSX. Even injected engines can show "carburetor icing" in certain conditions. The only remedy is to use Carb Heating, normally assigned to the "H" key.
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