It's official I got it back in the air... BUT-

[Dream to fly]

So after three months I finally got it back in the air and after all the testing, run ups and taxi tests everything was absolutely perfect.  Engine could without issue start every time on the second prop swing.   Here is what happened briefly: This is a rough time line but you get the general idea.  1967 M20F fuel injected

1. started engine leaned mixture
2. RPM up for mag check and turned mixture in one turn. 
3. full throttle for take off engine coughed once but went immediately to full power.  (I was super excited I might have pushed too fast)
4. in the air set cruise at 3500 ft  for a 20 minute flight leaned mixture to my preset red line on the exhaust temp.  Plane flew awesome.  Everything seemed right.  no coughing plenty of power. 
5. 10 miles out start a decent to pattern altitude and bleed off speed. 
6. 5 miles out gear comes down throttle back a little one turn in on mixture. temps are good engine sounds great. 
7. over the threshold pull throttle and engine quits.  push mixture and throttle in and engine starts.  EYES are wide open now.  engine sounds rough.
8. land uneventful try to taxi and  engine coughs every time I push throttle in pull mixture out a little it clears up ( I think it is flooding) come to a stop and push throttle to full power and it coughs give it more mixture and it clears up engine pulls the plane on the wet taxiway with brakes applied. 
9. not touching mixture pull throttle to idle smoothly and engine comes down and coughs tries to stall like its flooding pull mixture half way out  and it levels out so smooth like nothing ever happened a minute later engine stalls.

I am confused if you set the mixture and the adjustment doesn't move what gives.  Is there something I missed or is there more wrong. 

 

[Dream to fly]

1 minute ago, peevee said:

What altitude is the field? If you're in cruise at 3500 I guess it isn't more than a thousand?

You don't go full rich in the pattern?

You're leaning for the taxi and just putting one turn in for takeoff? You're not leaning for peak rpm during the run-up?

field elevation is 1800.  I had weather and was low. 

When I first started flying this plane I would set the mixture for cruise and on landing go one or a little more turns in and never have an issue.  Today if I went full rich the engine would cough

After start up and  during taxi I lean so the plugs don't foul and I run lean till take off.  Then full rich minus a turn.  This is how the former owner had said to do it and I never had a problem.  Now I am thoroughly confused. 

[Dream to fly]

Something had to break.  Just got a phone call from a neighbor at the field and asked if I had brought the plane home.  His words " you had black smoke coming out of the bottom of the plane"  So it has to be rich?  But nothing was touched that has to do with fuel.  Both mags are new timed correctly.  top and bottom plugs are new.  ignition wires are new.  Correction we did replace the fuel selector. 

 

P.S.  I must have angered the universe again:  LOL  I can't win

 

[gsxrpilot]

I think the "full rich minus one turn" is a problem. I believe the engine should run even at full rich. I've never owned a naturally aspirated fuel injected Mooney, but my carby C would run at full rich up to over 8000 ft with no problem. It would produce better HP if I'd lean for best power, but it certainly wouldn't cough and die.

Does it only cough and want to die at idle?  Will it run at full throttle full rich?

[Dream to fly]

Just now, gsxrpilot said:

I think the "full rich minus one turn" is a problem. I believe the engine should run even at full rich. I've never owned a naturally aspirated fuel injected Mooney, but my carby C would run at full rich up to over 8000 ft with no problem. It would produce better HP if I'd lean for best power, but it certainly wouldn't cough and die.

Does it only cough and want to die at idle?  Will it run at full throttle full rich?

If I go full rich at full throttle it coughs - pull mixture back maybe an inch it clears and reapply mixture it will pull the plane with brakes applied.

full rich at idle it stumbles and misses and was told black smoke is coming out my exhaust.  pull the mixture two inches and it smoothes out. then stalls after a minute or two

 

[MB65E]

How old is the fuel servo and spider?

i would pull both and send off for inspection.

what is the rise at 900 rpm when you pull the mixture?

-Matt

[takair]

One simple test that I do on every shutdown is a good verification of idle mixture.  With the engine at 1000RPM, pull the mixture to cut-off.  You should see a slight rise of about 50 rpm.  More than that and you are rich, less than that and you are Lean.  It is a simple adjustment by your mechanic on the fuel servo.

when you say it stumbles at full throttle, is this immediately after going to full throttle?  What if you slowly increase throttle?  I would start by checking your idle mixture.  It should be set after warmup, many times people don't let the engine get warm before setting idle rpm and mixture.

[Dream to fly]

Just now, MB65E said:

How old is the fuel servo and spider?

i would pull both and send off for inspection.

what is the rise at 900 rpm when you pull the mixture?

-Matt

I don't know the age.  I can go check the rise at 900.  (make sure I do the test right)  idle to 900 get engine to run smooth with mixture control.  let it stabilize then pull mixture full lean and watch rpm rise before shut down

 

[Dream to fly]

Just now, takair said:

One simple test that I do on every shutdown is a good verification of idle mixture.  With the engine at 1000RPM, pull the mixture to cut-off.  You should see a slight rise of about 50 rpm.  More than that and you are rich, less than that and you are Lean.  It is a simple adjustment by your mechanic on the fuel servo.

when you say it stumbles at full throttle, is this immediately after going to full throttle?  What if you slowly increase throttle?  I would start by checking your idle mixture.  It should be set after warmup, many times people don't let the engine get warm before setting idle rpm and mixture.

If I push to fast it chokes when the throttle it at WOT and it won't recover.  If I slowly increase it will stumble at WOT and it misses every few rotations.

[takair]

When you check idle mixture, it is from full rich.  Based on your description it is way too rich.  I would get it adjusted and assume that they will need to change the idle RPM too.  Idle mixture should not affect the full throttle mixture, but if it is way out of adjustment it might.  There is no other adjustment for full throttle mixture, so if that is still too rich, you may have another issue.

[Dream to fly]

Who rebuilds fuel servos and spiders

 

[Dream to fly]

So just came back from airport.  at idle and full rich engine is at operating temp.  Pull mixture to cut off engine rpm goes from 700 and rough to 900 smooth and quits.  Its got to be rich but why?  Anyone want to buy a plane it might have a few slug holes in it soon

[Marauder]

So just came back from airport.  at idle and full rich engine is at operating temp.  Pull mixture to cut off engine rpm goes from 700 and rough to 900 smooth and quits.  Its got to be rich but why?  Anyone want to buy a plane it might have a few slug holes in it soon

You'll get past this phase. Trust me, most of us have been where you are now.


Sent from my iPhone using Tapatalk Pro

[gsxrpilot]

I usually don't plug MAPA very much, but this would be a good reason to join. mooneypilots.com. The MAPA email list is (in my opinion) not nearly as good as MooneySpace. BUT... Don Maxwell is very active on the MAPA email list. And posting this type of question to the MAPA mail list would most likely get a quick and accurate diagnosis from Don.  You could also just give him a call, but calling is basically asking someone to provide services for free over the phone, in my mind. But posting to an email list or forum and getting an unsolicited response is different.

He's a member here as well but rarely checks in.

[Hank]

10 minutes ago, Marauder said:

You'll get past this phase. Trust me, most of us have been where you are now.
 

Yeah, I'm there with my stinking left mag. It was sent off and reworked after inflight failure, lasted 3 hours bringing it home, sent back out, still rough and 200 RPM drop and lots of vibration. Now I have a new ignition harness, swapped out the bottom left plugs and it runs pretty smooth, just still has a 200 RPM drop. Not cool. The mag was OH'd by Kelly a couple of years ago; the condenser wire was left rubbing on the gear until failure in March.

The destination mechanic sent it to Quality in Tulsa. It ran great on the flight home, just not since then. It's been two frustrating months with way too much work travel, and no A&P at my home field. Now I'm about to pull it off again, in a holiday weekend when I had planned to fly away . . . .

[MB65E]

I would rule out the servo and spider. Send it to RLB accessory service in Addison IL. 

(630) 543-9213

Probably around $2500 for both to overhaul. They might be able to fix it, but my guess is it needs an overhaul anyway. I know it's a huge expense, but the fuel air mixture is the most important thing on the airplane. Otherwise we have really heavy gliders...

You might pull the finger screen on the left side of the servo first. I'd bet your tech didn't check it. It could be impacted with garbage.

good luck!!

-Matt

[takair]

1 hour ago, Dream to fly said:

So just came back from airport.  at idle and full rich engine is at operating temp.  Pull mixture to cut off engine rpm goes from 700 and rough to 900 smooth and quits.  Its got to be rich but why?  Anyone want to buy a plane it might have a few slug holes in it soon

Have your mechanic start with the idle mixture adjustment.  I just had to adjust it for a friend fresh out of annual because it somehow got misadjusted.  The adjustment is typically held in place by friction of a compressed spring.  With the side panel off it is a fast adjustment.  Start there with your mechanic.  it is possible that screw is so loose it is messing up or entire adjustment.  As Chris said, don't give up....small hurdle that will soon be forgotten once you get it squared away.  With the idle mixture that far off, this should be an easy problem to diagnose.

once the idle is set, make it part of your routine at shutdown to watch the RPM rise trend.  It will change with atmospheric conditions, but should not be drastic.  Perhaps 50 +_ 25 RPM between seasons.  

[MB65E]

North Dakota temps and pressures have changed much in 3 months. Even in CA, adjusting the idle mixture is required when it's 50°, vs 105°.

-Matt

[MyNameIsNobody]

I would NOT be airborne with this machine until it does NOT stumble at idle or full power.  It is not safe until this is resolved (on the ground).  I agree that this is a small adjustment that when identified will transform the engine into normal solid operation.  Until diagnosed and adjusted (Just say NO).

[Cyril Gibb]

15 hours ago, Dream to fly said:

So just came back from airport.  at idle and full rich engine is at operating temp.  Pull mixture to cut off engine rpm goes from 700 and rough to 900 smooth and quits.  Its got to be rich but why?  Anyone want to buy a plane it might have a few slug holes in it soon

Sounds like you have a 200 rpm rise when it should be 50.  Waaaay too rich idle mixture.  Simple easy adjustment.  Adjust that first.  Then adjust idle speed to 700-750 rpm.  Adjust them when the engine is warm.  Your idle mixture appears so rich that the mixture setting / idle speed setting might take an iteration or two.

Then try it.  Note that rpm rise check is from 900-1000 rpm or so.

If there is a hangar fairy around, the idle mixture is a threaded turn thing with an arrow and a "rich" word stamped into it.  Tell the fairy to turn it opposite the arrow.

[Dream to fly]

6 hours ago, MyNameIsNobody said:

I would NOT be airborne with this machine until it does NOT stumble at idle or full power.  It is not safe until this is resolved (on the ground).  I agree that this is a small adjustment that when identified will transform the engine into normal solid operation.  Until diagnosed and adjusted (Just say NO).

Agreed.  I am not going airborne.  PROMISE.   my eyes were about a foot outside my head when everything went quiet.     I am going to lean this thing out and I am going to build an adapter that will allow my 5 gas analyzer to read the exhaust.  I am getting this right before it goes up again or Coke/Pepsi can have free aluminum for cans.  It has to be rich black smoke and a 200+ rpm rise.  nothing else makes sense.  My only question is why.   Nothing was touched fuel mixture wise. 

[Dream to fly]

4 hours ago, Cyril Gibb said:

If there is a hangar fairy around, the idle mixture is a threaded turn thing with an arrow and a "rich" word stamped into it.  Tell the fairy to turn it opposite the arrow.

I have already left fairy dust and crackers for them.    And a big arrow that tells them which way to turn it.

[Yetti]

Blue smoke is rich Black is something else.   I would scope the muffler

[Guest]

Blue smoke is usually oil, black is carbon or rich mixture.

Clarence

[Yetti]

oops its been awhile since my teen years