Mixture Throttle Idle Issue

[DaMooneyMan]

Hello fellow Mooney pilots. 

Have a quick question for you all. 

On shut down from a flight last night I pulled the mixture to shut down and the engine didn't shut down. I had to pull the throttle all the way to idle and she finally cut off. Interesting given the fact...

Just had my 1st oil change the day previous to the flight. Before the oil change and running the mineral oil had no issue. I am think there may be a connection here???

After making a successful landing and heading the the hold short line. I pulled the power to idle and the engine died. Mixture was full rich.

Read one post in the forum here. Seen something kinda similar. What was suggested was the mixture setting needed to be adjust. What are you all thoughts? 

Edited May 25, 2017 by DaMooneyMan

[Supercop0184]

What airplane and engine are you running?

Sent from my iPhone using Tapatalk

[bonal]

Looks like we have another new Mooney Space guy. Welcome, if you note his discription it's a K and I'm sure I will be corrected but I think a 231. Sorry I can't be of much help but others will chime in soon. As always attach some pictures.

[jlunseth]

It is probably two separate problems.  I wonder if your mechanic adjusted the fuel flow when he did the oil change, because it sounds like the idle fuel flow is too rich.  At any rate, the cure is to properly adjust the idle fuel flow and cutoff.  

On the engine running rough when you try LOP, that is not unusual, some engines just won't run LOP.  Mine did not until I had the engine IRAN'd a few years ago, and now it is smooth as a kitten.  It can be done, but you probably are going to need GAMIs in a 231 in order to do it, the induction system is going to need to be thoroughly checked for leaks, and you may need to rework the "spider," i.e. the fuel distribution system.  I run mine LOP all the time now and have for a couple of years, it can be done in with the TSIO-360-LB. If you have the MB that's even better.  

Edited May 8, 2016 by jlunseth

[Shadrach]

Correlation vs Causation.  

Seems highly unlikely that changing oil type would have any bearing on fuel delivery.  When was the last time the fuel servo was open?

[Yetti]

So you were running mineral oil...  so you had an engine swap out say 25 hours ago...  so the mixture and throttle cables have been disconnected recently during the engine swap... so they probably did not get tightened up/have slipped loose/need to be fine tune adjusted.

Don't fly it if you go to idle and the engine dies.  That is a run up checklist item.

 

 

[Guest]

3 hours ago, DaMooneyMan said:

Hello fellow Mooney pilots. 

Have a quick question for you all. 

On shut down from a flight last night I pulled the mixture to shut down and the engine didn't shut down. I had to pull the throttle all the way to idle and she finally cut off. Interesting given the fact...

1. Just had my 1st oil change the day previous to the flight. Before the oil change and running the mineral oil had no issue. I am think there may be a connection here???

After making a successful landing and heading the the hold short line. I pulled the power to idle and the engine died. Mixture was full rich.

In flight at 5,500 at 2400 RPM 33 inches started to lean got to about 11GPM she started running rough. So I made the mixture rich again. Flew the rest of the flight 2500 RPM 34 inches at 13 GPM.

Read one post in the forum here. Seen something kinda similar. What was suggested was the mixture setting needed to be adjust. What are you all thoughts? 

It sounds like it's time to have your engine fuel system set up checked per Continental SID97-3E.  It critical to the health of your engine.

A quick search will find it.

Clarence

[DaMooneyMan]

Thanks fellas. I have a continental TSIO 360- LB a M20K 231. 

On the run up and flight from Houston to Corpus everything went fine. All the needles were dead center in the green enroute. It looks great a lot better than the previous 25 hours. 

On the run up at Corpus no issues. Just noticed the issue when I reached alitude. 

Like I said hadn't experienced this issue when I was running mineral oil. So I am thinking the mechanic might have done something or something else. One thing I noted we put 8 qts of oil in the engine. On the preflight checked the oil it was at 5.5 qts. No leakage no nothing however I THINK the mechanic might have took some out. When we started up engine the day previous to the flight the oil pressure was high and once stabilized it was at the top range of the green. 

 

 

[carusoam]

"Flew the rest of the flight 2500 RPM 34 inches at 13 GPM."- DMM

Clearly something wrong... 13gpm would be 780gph.  You ran out of fuel. 

Sorry, just joking with the new guy. Looks like you got plenty of good responses from some strong technical resources.

Welcome aboard,

-a-

[jlunseth]

On the oil quantity, you don't say if you ran the engine before you checked the oil.  It is common to have the dipstick reading fall because you ran the engine.  That distributes oil throughout the engine so you would expect to see the oil about a quart lower than before running the engine.  From 8.0 to 5.5 looks like its more than it should be, but you didn't say whether the 8 qts. was before the oil change or after.  Not uncommon to put 7 qts. in when changing the oil rather than the full 8.  Some engines will just blow the extra quart out quickly, and some mechanics just do 7.  So if the engine had 7 qts. in it after the oil change, and you then ran the engine, and then checked the oil, it would not be unusual to see 5.5.

Let the engine sit for a couple of days and then check the oil.  That will give you a reading you can compare to the 7 or 8 qts. that should be in the engine.

Do you have an intercooler?  If you do, the power setting sounds high to me by quite a bit.  

[DaMooneyMan]

Thanks for all the input. And no intercooler or waste gate yet.

I did go out to the Mooney the day after started up fine. Pulled the mixture on shit down as usual no issues. I did notice I had the fun pump on shut down the previous night. I turned the pump off before I started the engine And turned it off no issues .... 

I talked to the mechanic that changed the oil. He told me the reason for the engine not shutting down could be due to fuel pump being on. (I never mentioned that I had it on so he may be spot on here). 

Still does not exactly explain why the engine sputtered at altitude when leaning out. And why the engine died on the taxi way. 

Ran the problem past a Piper Pilot owner/friend  he is saying since I run ROP and I may have the plugs fowled. My TIT say 1650 is peak. I get to 1350 usually. However I get good GPH at that temp. Long story short I'm having the A&P check the mixture control setting and check the plus to see if they are fowled.

 

[jlunseth]

Well, were you also running the pump at altitude?  If you read your POH, you do not ever run the aux fuel pump in the 231 except for an emergency such as the engine fuel pump failing.  In some aircraft you do, such as for takeoff, but not the 231.  In the 231, if you run the fuel pump during normal operations whether the high or low boost, you will make the mixture over rich.  1350 TIT is too low for a cruise power setting.  So it is possible if you were running the fuel pump when you tried to go LOP, that you were still quite rich. 

I have it in my checklist to check the boost pumps both before takeoff and in the before-landing check, to make sure they are OFF.  They should always be off.

But not all engines will go LOP, and the 231 is an example of one that will, only if it is set up properly.  To run LOP, the engine must not have a large difference in fuel flow between the cylinders.  The induction system on the 360-LB is very untuned, and if you just have the factory injectors it is very likely you have a large difference in fuel flow between the cylinders, and you can't get LOP without sputtering. 

[Marcopolo]

Jlunseth is right on track, no low boost or high boost pump action at all while the engine is running (except in emergencies).  3-5 second prime with low boost before starting, but once running, no boost pump!

Edited May 13, 2016 by Marcopolo

[jlunseth]

I do use the boost for start, but in an unconventional way.  The typical start problem is that we prime the engine, it runs briefly on the prime fuel and then quits.  We do that again.  And again.  Etc.  Until it actually keeps running.  This happens either because the lines are not full or the mechanical pump is not fully primed, in other words the engine is not getting fuel.  There is an easy way to start that works in my engine, hot or cold start, low or high altitude, every single time.  First, before priming, and with the throttle and idle mixture full out (idle cutoff), I run the high boost until the fuel pressure stabilizes on my JPI930.  Now, the experts who showed me this said that there is a fuel return line on the Continental and that one can run the high boost for a full minute without causing any issues because excess fuel just gets returned.  I have found that to be dead wrong.  If I use the high boost too long I can produce a backfire, which tells me the fuel is going someplace other than back to the tank. So I just run the boost until the pressure comes up and stabilizes at some number.  If you don't have a good fuel pressure indicator just run the high boost for 6 seconds with the throttle and mixture full out (off), that will do it or close enough.  All you are doing is making sure the fuel lines are full.

OK, now the line is full, step two is to put the throttle and mixture full in and prime with the primer button for whatever period the POH says (it is dependent on OAT).

Step three is the most important I think.  Pull the throttle out to the start position ( I use about one third throttle).  Now, leave the safety cage over the high boost but put your finger just on one corner of the button.  Do this with your right hand.  With your left hand, hit the starter.  The engine will fire and then may start to slow down.  When it starts to slow down, push in on the corner of the high boost.  If you leave the safety cage over it, it acts like an "instant on-instant off" button, in other words, the second you take your finger away the pump stops.  Run the high boost just long enough for the engine to get going well, then stop pumping.

As I said, in the 231, this will work every time, in all conditions except down below about 20 dF when you really need to heat the engine first.

Other than that, no use for the boost pumps except emergencies.