Rough engine (Lycoming IO-360-A1B6)

[M252]

A friend of mine operates a DR500 (not a Mooney), however, as it is equipped with a Lycoming IO-360-A1B6 engine I thought that maybe some you M20J operators have an idea:

1. -          He has been experiencing a rough engine, especially when the engine is warm

2. -          The engine also runs rough after fuel stops or when going around. He notices vibration “in the feet”

3. -          Also, performance is reduced

4. -          When he runs the engine at idle there are irregular (ignition) interruptions associated with reduced RPM

5. -          When he quickly pulls back the throttle cylinder 1 cools more quickly than the others

 

The fuel injection system, ignition system, governor and magnets have all been replaced. In addition, they have also checked cylinders and valves.

[ArtVandelay]

A friend of mine operates a DR500 (not a Mooney), however, as it is equipped with a Lycoming IO-360-A1B6 engine I thought that maybe some you M20J operators have an idea:

1. -          He has been experiencing a rough engine, especially when the engine is warm
   
2. -          The engine also runs rough after fuel stops or when going around. He notices vibration “in the feet”
   
3. -          Also, performance is reduced
   
4. -          When he runs the engine at idle there are irregular (ignition) interruptions associated with reduced RPM
   
5. -          When he quickly pulls back the throttle cylinder 1 cools more quickly than the others
   

 

The fuel injection system, ignition system, governor and magnets have all been replaced. In addition, they have also checked cylinders and valves.

Does have a engine monitor that he can download the data from?

[M252]

Good question, I will check.

[M252]

Unfortunately, an old EDM 300, do not believe you can download data from that

[M252]

Sorry, EDM 700

[ArtVandelay]

Sorry, EDM 700

I thought you could with a serial interface, if you look behind the panel you might see a dangling 9-pin connector, maybe someone with the 700 can chime in.

[jwilcoxon78]

Does it run rougher on one mag vs. the other?  Valve stem clearance checked?

[KSMooniac]

Not all EDM-700 units had that download option, unfortunately.

How much time on the engine? What type of spark plugs, and how long in service? I'd check resistance of all of them, and maybe do a valve wobble check.

Sent from my LG-LS997 using Tapatalk

[M252]

Thanks for the hints, I think they have replaced all spark plugs, the engine is mid-time. Maybe the valves need to get more attention. I'll let him know.

Edited May 1, 2017 by M252

[KSMooniac]

If they used champion plugs I'd still measure the resistance of them. It doesn't take long for their plugs to fail.

Sent from my LG-LS997 using Tapatalk

[M252]

Good hint, will do!

[N201MKTurbo]

Does he see any change in EGT on any cylinder when it gets rough? The most likely cause is mags which will show up as an EGT change. 

If he has a valve problem the EGT will go down when it gets rough. An ignition problem will make it go up unless he looses both plugs in which case it will get very rough and the EGTs will drop.

[Oldguy]

Has anyone looked at the fuel pump? Not sure if he has an electric fuel boost or not, but from reading the symptoms, I would look at the fuel and air portions of combustion.

Also, how long has this been occurring? Any possibility of fuel contamination?

[carusoam]

+1 on checking the label on the spark plugs...

If he has changed everything but them... it is time to measure their resistance while installing the replacements with the other brand name...

Best regards,

-a-

Edited May 2, 2017 by carusoam

[bradp]

Just put the other brand spark plugs in first. It's cheaper than anything else. If that doesn't clear up the issue I'd think wobble test, look at mags again (slick mags are just as bad as the champion plugs- breaks in secondary coil are common and manifest as difficulty when the engine is warm/hot), look at ignition harnesses. To test mags/harnesses en block, call lycoming technical support and ask them what the air gap specification is for your engine / mag combo. Disconnect plugs. Bring to TDC on Cyl #1, click through impulse couple and you should see a spark from the lead spring to a good ground across an air gap of ? (Something like 3/4"). Rinse and repeat for each lead.

 

 

Sent from my iPhone using Tapatalk

 

[M252]

Thank you for the excellent hints.  I have forwarded them and will let you know what they found.