Hey all, I haven't been simming much lately but decided to take the default (FS9) 172 for a quick ride and do a few 360s around a small airport that serves Caracas (ICAO: SVCS).It is at an altitude of 2145' ASL. To my surprise (tried this with both AS6.5 and weather set to clear), after starting the engine and closing the throttle to idle, the RPM would descend below 500 and then the engine stops after a few seconds, showing the "oil press" in the announciator panel. I haven't been able to reproduce that with any of the stock Cessnas 182 or 208. Could any of you please try to reproduce that and post the results here? I would like to know if it has anything to do with my computer. As a side note, something similar happened a few months ago when I met a local flying buddy that was showing me FSX and his new Carenado Stationair (same airport) and the engine would also stop if left at idle, but IIRC the FSX 172 worked fine back then. I don't have that aircraft for FS9 so I don't know if it's the same for this version. If any of you has it, please post your results as well.take care,Enrique

Hi Enrique, I just loaded the stock FS9 cessna172 at SVCS with cleared weather. (stock afcad and scenery) I get the same drop in rpm to 500 rpm and oil pressure warning, but the engine continues to run. I ended the flight and moved to KSEA to compare, rpm at 550 and no oil pressure warning. I just went back and flew a half circuit around SVSC at approximately 3000 feet, no problem while in the air. To make a further check I loaded a flight at KDEN, 5440 feet, and got the same rpm and pressure drop as at SVCS and still no engine shut down. I had never noticed the oil pressure drop in the past but I rarely use the annunciator panel on the C172, so I suppose everything but the engine quiting is normal. Sorry, but I have no answer for that part of the issue. I hope this helps at least a little bit.Regards,Mel

I don't remember if it has one, (the default 172), but I usually lean out the fuel mixture to about 50% at high altitudes in small GA aircraft. That way the engine doesn't stall out on me.Mark

Differences between C-172 and C-182 Engines (Parameters):-------------------------------------------------General Engine:172: fuel_flow_scalar= 0.88 //s/b 1.00 or 0.98 ? 182: fuel_flow_scalar= 1.00Propeller:172: propeller_diameter= 6.3 182: propeller_diameter= 6.58172: prop_tc= 0 //s/b 0.1 ? 182: prop_tc= 0.1-------------------------------------------------Fix: (1). Change c172 to 'normal' specs (as is 182).(2). Reduce the idle friction scalar (for the C-172). ie: idle_rpm_friction_scalar= 0.8 //orig=1.0 (this by itself should 'cure' the shut off problem, at Hi Alt or on ground). My 2 cents worth.CBNapamulePS: Mark. Idle AND lean mixture (at high altitutes)??? Yeah, that COULD happen (but not on any of MY flights-hehe).

The engine is running too rich at that altitude. Lean the fuel and you will be fine.

Differences between C-172 and C-182 Engines (Parameters):-------------------------------------------------General Engine:172: fuel_flow_scalar= 0.88 //s/b 1.00 or 0.98 ? 182: fuel_flow_scalar= 1.00Propeller:172: propeller_diameter= 6.3 182: propeller_diameter= 6.58172: prop_tc= 0 //s/b 0.1 ? 182: prop_tc= 0.1-------------------------------------------------Fix: (1). Change c172 to 'normal' specs (as is 182).(2). Reduce the idle friction scalar (for the C-172). ie: idle_rpm_friction_scalar= 0.8 //orig=1.0 (this by itself should 'cure' the shut off problem, at Hi Alt or on ground). My 2 cents worth.CBNapamulePS: Mark. Idle AND lean mixture (at high altitutes)??? Yeah, that COULD happen (but not on any of MY flights-hehe).

Well, I didn't say anything about idle but perhaps I should have mentioned that you probably would need to give the engine a bit more throttle when leaning it out. Forgot about that little wrinkle...thanks for reminding me Napa guy :)Mark

Mark,Was just kidding of course. The way I lean the mixture is to reduce mixture until engine 'coughs', then I increase a little bit rich from there and that's it. I don't know what percentage that is, but it works for me.CBNapa Mule(Mule=delivery driver (auto parts - my last job -as I am retired now).

Thank you all for your input. It made me aware that I had recently enabled auto mixture for some reason and failed to take that into account when I was doing the 'tests' posted earlier. Jeez, getting old is great, . . . , I just can't remember why! Thanks again.Best regards to all,Mel

snip---------To my surprise (tried this with both AS6.5 and weather set to clear), after starting the engine and closing the throttle to idle, the RPM would descend below 500 and then the engine stops after a few seconds, showing the "oil press" in the announciator panel. take care,Enrique

This will occur at Seal Level which has nothing to do with leaning the mixture. Some computer systems will cause the idle on the default 172 to drop after a time period of 500 RPM's. That will cause the oil pressure to drop and the engine shutdown. The problem was reported to ACES in both FS9 and FSX before the update release but did not get fixed.I have not tried napamule's tweak in the .cfg but it might fix the problem without raising the RPM's when idling for any extented period.jim

This will occur at Seal Level which has nothing to do with leaning the mixture. Some computer systems will cause the idle on the default 172 to drop after a time period of 500 RPM's. That will cause the oil pressure to drop and the engine shutdown. The problem was reported to ACES in both FS9 and FSX before the update release but did not get fixed.I have not tried napamule's tweak in the .cfg but it might fix the problem without raising the RPM's when idling for any extented period.jim

Ah, interesting. You know Jim, I've never experienced that in the default 172 but if you say so I believe you. However, when I fly out of Denver or Mexico City I have to lean the fuel mixture and give the engine a bit of throttle or it will conk out.NapaMule, I know you were joshing...we Californian's need to stick together. I'm working in Sydney right now but will be home in good old Santa Monica soon!Mark

SwoopThe testing was done at sea level so we did not have to lean in order to see the problem. I agree if parked at airports above sea level the mixture is leaned to maintain a continuos idle. jim

Hey all, thanks for your replies and taking the time to test this!I spoke to my local buddy who confirmed this happens to him in FSX using Carenado's Stationair but not with Carenado's 172. He was also unable to reproduce this with the Default 172 in FSX.Thanks to Jim for the info, I'm 90% sure that this wasn't happening in FS9 in my previous system, so it really must be that this FS9 bug shows up randomly in different computer systems?I will try to adjust the parameters as per napamule's advice (thanks!).By the way, I have flown right seat to and from this particular airport in real life in a few 182s (but never in a 172), and I don't recall leaning the mixture nor having to open the throttles to keep the engine from stalling in the ground (then again, they were idle for short amounts of time).Thanks again to everyone,cheers!Enrique

Another factor to mention, maybe someone did and I missed it, is density altitude.IMO 2145 feet ASL is not that high and a C172 should run fine at full rich.....unless it is a hot day.Heat adds feet!Usually most normally aspirated piston engines run fine under 3000' at full rich and some up to 5000' easily.What was the weather like when you were trying to take off at 2145' ASL.regards,Joe

Hi Joe, it was a relatively hot day, close to 27 degrees Celsius.But IMO not enough to cause that effect. I also tried clearing the weather, with the temp close to 15 C. Same behaviour.Odd isn't it?cheersEnrique

Hi Enrique, I just loaded the stock FS9 cessna172 at SVCS with cleared weather. (stock afcad and scenery) I get the same drop in rpm to 500 rpm and oil pressure warning, but the engine continues to run. I ended the flight and moved to KSEA to compare, rpm at 550 and no oil pressure warning. I just went back and flew a half circuit around SVSC at approximately 3000 feet, no problem while in the air. To make a further check I loaded a flight at KDEN, 5440 feet, and got the same rpm and pressure drop as at SVCS and still no engine shut down. I had never noticed the oil pressure drop in the past but I rarely use the annunciator panel on the C172, so I suppose everything but the engine quiting is normal. Sorry, but I have no answer for that part of the issue. I hope this helps at least a little bit.Regards,Mel

Several things I've noticed...

• Using AFSD to monitor the parameters (same test as above), pulling the throttle back to the stop on the c172 will allow the engine to drop - not to an arbitrary 500 rpm, but on my test 452 rpm.
• The C172 is carburetted - the C182 is fuel injected (more precise fuel/air metering) and of course the C208 is turbine with a fancy fuel metering system.
• Air temp, actual air pressure, density, humidity will all affect the F/A mixture, and even though FS tries to maintain 0.083 it's not that precise.
• Simply increasing the throttle to maintain 550-600 rpm will bring up the oil pressure
• I'm willing to bet a lot of real C172's aren't any less finicky and pilots have learned to fine-tune their techniques.

I know MS didn't hit every mark perfectly (nor corrected the small details that slipped by) but then they missed the mark on a lot of bigger items like ATC, airports, terrain, etc. Heck, they let us fly a 747 without even taking a PPL groundschool course. Anyone who's lived with a cranky old radial like the P&W R985 knows aero engines are never a "set it and forget it" bit of engineering. Of course, the newer aircraft let us think so, but their internal computers are making those adjustments thousands of times a minute that we don't think about. On the other hand I see more and more of a tendency these days for people to jump in and "fix" an "obviously flawed a/c file" rather than modifying pilot behaviour or perhaps refining one's skills a tiny bit. In the "real world" (if we want to really simulate it) it is illegal for a pilot/owner, unless he is a certified AME, to adjust/modify his aircraft without rendering the C of A invalid :( -and all changes should be documented in the a/c or engine logbooks ( or a/c .cfg file) for future reference. Rob