[GEM930]

I guess this could be RV related as there are more than
a few RVs flying around with 200hp angle valve 360s. It is actually a Mooney M20e that had the problem, I'm about to describe, however.
Here goes.... Please bare with me... My 6a has been grounded for a while for an engine upgrade and I have been flying a friends Mooney a little. *Last week I took it to Reno to pick up a friends son. *Density altitude was 7700' and we were 115 under gross. *Take off was not sensational, but not scary either. *Two days ago the same friend and I were taking off from Fallon muni. *on our way to Bonnaville fir speed week. *Density altitude was 6000' (field ele is 3966) and we were 220 under gross. *I leaned (same as Reno) about 3/4 inch for take off since density altitude was so high. *Mag check at 1500 rpm was fine, *when I pushed the throttle forward the engine started to miss horribly. *I aborted take off and pulled off the taxi way and conducted another Mag check as this plane is notorious for loading the plugs.... Mag check at 1500 with fine??? I taxied back to parking and noticed a guy standing in front of a hangar with another mooney in it. *He was very helpful and asked if I leaned for take off and I told him I had slightly. *He climbed in and we did another mag check at 1500 (all good), then he had me increase rpm , at 1800 it started to miss. *He pulled the mixture back until it ran smooth and then had me go to 2700. It started to miss again and pulled the mixture back until it ran smooth..... Holly Cow!!! The mixture seemed like it was 3/4 of the way out. He stated "there is your take off setting"... Ok than... He obviously knows more about this than I do... I went to take off and about wet myself! Could barely get 200 ft/min. * If I tried to enrich the mixture any from that point it would miss, if I leaned I would lose rpm (until the cs propelled adjusted) *Once I (finally) got the plane to about 7000' I played more with the mixture. *Any movement at all had the same effect ... Rich = run rough... Lean .... Lose power. *I eventually made it to 10500' but cancelled the plan to head to Bonnaville and flew back to my home airport, Chico. I played with the mixture at 10500 still with same effect. *The plane was running fine id I left the mixture alone, so once over the mountain I did not touch anything. Approaching Chico and below about 4000' i check the mixture and it seemed to function normally. * During the flight the CHTs were between 360 and 380 on 1,3&4 ... 2 was jumping around between 195 and 215. *It appears the probe is bad. *The EGTs . *Were around 1300 on 1,3&4 and 1100 on #2. *Checked compression this morning all 74s and 72s. *The owner flew it once around the pattern and reported it felt normal. *Density altitude was 2500'. *Field elevation here is 240'. *Top plugs looked great. *Did not check lower plugs. *The owner is pretty sure it was just loaded up, but I'm not sure how it could stay "loaded up" then I was at 2500 rpm and 18 or 19" for 45 minutes and it would still miss or lose power with even the slightest movement of the mixture.
I realize this was really long, I hope I did not put anyone asleep. Any ideas??? Is it possible the plugs were just fouled in such a way it would behave as I have described?
I am a little afraid to fly it anymore. *

 

[Bruce]

Gem,

I would check #2.
Switch probes if possible and check both plugs and wires.

You should burn off fouled plugs when you go to lean mixture
and high RPM.

Also check fuel nozzle to #2 cylinder on top.
Could be blocked.
Put in Hopps #9 gun cleaner.

Hope it helps.

 

[RV10inOz]

Ohh dear, this is a classic example of why I harp on about engine monitors and doing an APS course.

For all your questions I have about two in return. Basically, plugs need to be in good order, not worn out, gapped below 0.018", resistance below 5K and all the leads and magneto in good condition.

Next, if you have all cylinder monitoring, which you do, you need to verify the following.

Fuel Flow at a DA near sea level, to be around 20GPH (assuming its the 200HP) and note the EGT you get as you pass through 500 feet AMSL. This is your number at higher altitude airports. (expect it to be 1250-1320F depending on probe placement)

As for leaning on the ground and in the climb, refer to the John Deakin articles or my other posts. No need to repeat it all here.

My experience with a Mooney that is at or near MTOW on a hot day........Thanks God the earth is round not flat!

 

[BobTurner]

The "normal mag check is okay but it fails at higher power" is a classic symptom of ignition problems. Either marginal plugs or marginal mags. Since it failed at higher altitude my vote would be weak mags.

 

[sailvi767]

One thing I have noted is that the normal mag check can mask issues. If you have one cold plug during a 1700 RPM check the engine will run almost perfect. There will be little vibration ect.. when selecting the ignition system with a cold plug. I would have expected the opposite. I now carefully watch each EGT during a mag check and give them time to reflect any issues. Cycling through the ignition system at idle will show a cold plug instantly with a large increase in vibration and rough running.

George

 

[Walt]

If the plugs are loaded up with lead (very likely) they will not clear themselves by running lean. Pull all the plugs, clean & gap them, then check leads, compression and timing while your there.

 

[GEM930]

Thanks everybody... Sounds like ignition is the place to start.