IO360AIA Rough Running Engine

[Cabo Lee]

I have a 1966 M20e, that developed a rough running engine. I am working with my AP and we have not

been able to solve the problem longer than 1 hour. The engine runs fine for an hour with cleaned plugs/

injectors but start to run rough first on Left Magneto than Right Magneto. Here a short list of what has been

done:

1. Cleaned Fuel injectors with new screens under cap

2. Flow tested injector all even spray fuel into bottle evenly with

    clean fuel.

2. All new spark plugs.

3.Compression check; 68, 76, 75,76/80

5. Rebuilt Left & Right Magneto less than 25 hours ago.

6. New Spark Plug wires less than 25 hour ago.

Any suggestions? The major issue is with clean plugs/injectors runs very well for about an hour or until shut down.

Once shut down, on restart, it misses first on Left Magneto and than on the Right Magneto, than both Magnetos. Suggestions?

[Brian Scranton]

Is the timing off? 

Also, welcome to Mooneyspace! Be prepared for 10 guys to ask you about your engine monitor and downloading it to Savvy Analysis.

[kortopates]

2 minutes ago, Brian Scranton said:

Is the timing off? 

Also, welcome to Mooneyspace! Be prepared for 10 guys to ask you about your engine monitor and downloading it to Savvy Analysis.

Is there a smarter way before turning wrenches that isn't data driven?

After an hour inflight when the roughness returns, a LOP mag test should show the problem very well and eliminate the guess work.

[Brian Scranton]

40 minutes ago, kortopates said:

Is there a smarter way before turning wrenches that isn't data driven?

After an hour inflight when the roughness returns, a LOP mag test should show the problem very well and eliminate the guess work.

Of course not! It's just that I'd wager to say 1/2 of the guys on here looking for advice don't have good engine monitors. Then we spend most of the time in the thread talking about how important a good engine monitor is. And this nice guys just wants to solve his problem. Which of course all starts with the fact that he probably doesn't have a good engine monitor. I just thought I'd get it out of the way! 

[kortopates]

Just now, Brian Scranton said:

Of course not! It's just that I'd wager to say 1/2 of the guys on here looking for advice don't have good engine monitors. Then we spend most of the time in the thread talking about how important a good engine monitor is. And this nice guys just wants to solve his problem. Which of course all starts with the fact that he probably doesn't have a good engine monitor. I just thought I'd get it out of the way! 

Of course you are so right! Too many people just don't realize how important they are; primarily because they just don't yet understand how to use them.  

[Cabo Lee]

Thanks for the input. I am sorry, I fail to state, I have an older model engine analyzer Insight Gem 602. I probably

do not know how to use it properly ( installed maybe 25 hours ago). This unit does not allow any down loading of data. 

I have basically done ground operation and high speed taxi on the runway without getting airborne. I do not plan to get

airborne until, it operate properly on the ground. I did not notice, anything unusual with the engine analyzer. What

should I be looking for with the 602, in EGT or CHT / or other areas causing the problem.

Edited May 8, 2017 by Cabo Lee
correct to phrases

[Brian Scranton]

So many questions... we'll let others chime in too. 

1) Is the roughness at idle and all other power settings? 

2) Have you pulled and cleaned your injectors more than once? And that works for about an hour? 

3) Have you checked your fuel screen? Is there trash in it? Even if you clean your injectors, if there is trash in the system they will keep getting clogged--that will produce roughness for sure! 

4) Has your A&P checked your mag timing? That would be a culprit--since you were running fine until you overhauled your mags. Make sure you set to 25 TDC (or 20) depending on the stamp on your engine block. Some A1As run 25 others run 20. 

5) Are you getting good, consistent fuel flow? Do you have a FF gauge? 

6) When you lean on the ground at 1000rpm, see a rise in RPM, then a drop as you continue to lean, are all your EGTs rising? When you switch to the left mag, do you see a rise in EGT? Same with right mag? 

Let's start there...

[kortopates]

You really need the down load capability to properly analyze. But what you would do, after an hour of flying when you start to experience the roughness, Lean the engine to LOP, if you were cruising ROP, aiming for about 50 LOP if you can, then do an inflight mag test. You really need an autopilot or another pilot on board to do this. Put the unit in to Normalize mode (I don't recall if the 602 supports this, if not proceed without it) so that all the EGTs are even at 50% height. Then switch from both to a single Mag and look for a steady rise on each EGT for about 30 sec at least. If you see one that does not go up, expect to see that one go down on the other mag indicating only 1 plug is firing in that cyl. If you see one EGT go up and down erratically that is a problem too indicative of the plug missing. Denote the mag position and cyl # of any anomaly. Switch back to both for 30 sec to allow EGT to stabilize before switching to the other mag. If you see a couple spark plugs missing pull them to inspect both the plug and the wire and check the plugs internal resistance; discarding  any with 5K ohms or more resistance. Or if you happen to see all the EGTs on a mag become erratic then its a Mag issue and the mag should be pulled and IRAN's. We can also tell if you have split timing between the mags, but that can only be seen if you are able to download the data and look at then.

I only focused on ignition, only because this is more common based on the symptoms to date and therefore I would start there. For example coils sometime fail only when they get hot after a while in cruise. But we really don't yet know if its an ignition issue.

[Yetti]

I vote your 68 cylinder is oil fouling the plugs.  Also are you leaning for taxi?  After sitting do you have oil on the lower spark plug wire fitting?

Maybe a worn valve guide.   May need to do a wobble test.

Oil fouling the plugs may be fixed by putting the BY plugs in the lower slots.

[takair]

As Yetti said, the plugs can tell a story, even without an analyzer.  What do the plugs look like after an hour?  After running an hour and then cooling down, does it run fine again or do you need to do something to make it run fine?  What effect does mixture have on the issue.  See the other thread where someone had FOD in the inlet.  Keep in mind, an hour of ground running is not the best thing for your engine and can cause other issues like fuel vaporizing and other overheat issues.  

[Guest]

What brand are your magnetos? And who overhauled them?

Clarence

[Shadrach]

4 hours ago, Cabo Lee said:

Thanks for the input. I am sorry, I fail to state, I have an older model engine analyzer Insight Gem 602. I probably

do not know how to use it properly ( installed maybe 25 hours ago). This unit does not allow any down loading of data. 

I have basically done ground operation and high speed taxi on the runway without getting airborne. I do not plan to get

airborne until, it operate properly on the ground. I did not notice, anything unusual with the engine analyzer. What

should I be looking for with the 602, in EGT or CHT / or other areas causing the problem.

I don't think this is a ignition timing issue other wise it wouldn't run fine for the first hour. I would be looking for other corollaries like temperature, fuel pressure and certainly EGTs. If the engine is running rough, it should show if a specific cylinder has a reduction is EGT or perhaps all cylinders if it's related to the fuel or ignition system on the whole. There's a lot of blind dart throwing going on in this thread, which is the least desirable method of trouble shooting. 

If it's running rough you should see some sort of EGT event when it happens. 

[Yetti]

2 hours ago, Shadrach said:

There's a lot of blind dart throwing going on in this thread, which is the least desirable method of trouble shooting.

Oh Please that is what mooneyspace is best at.  Limited data typed in by a non mechanic describing things.  It's always a multiple choice scenario

[neilpilot]

Speaking of blind darts, my intermittent issues with an IO360A1A went on for a couple of years.  My issue ended when an internal fault in the fuel servo block flow to all injectors, resulting in a forced landing and total loss. That's after I worked on cleaning injectors, cleaning and changing plugs, and had fuel injection OHed. After each step, such as cleaning injectors, problems would disappear for awhile.

I now have no injectors and life is good.

[Cyril Gibb]

6 hours ago, neilpilot said:

Speaking of blind darts, my intermittent issues with an IO360A1A went on for a couple of years.  My issue ended when an internal fault in the fuel servo block flow to all injectors, resulting in a forced landing and total loss. That's after I worked on cleaning injectors, cleaning and changing plugs, and had fuel injection OHed. After each step, such as cleaning injectors, problems would disappear for awhile.

I now have no injectors and life is good.

In the winter (typically 6 months in Canada) I often end up flying at night in IMC.  My #1 fear is total, sudden engine failure.  As a possible help in the future for others, what were the early symptoms and what was the internal fault that finally blocked fuel?

[Guest]

9 hours ago, neilpilot said:

Speaking of blind darts, my intermittent issues with an IO360A1A went on for a couple of years.  My issue ended when an internal fault in the fuel servo block flow to all injectors, resulting in a forced landing and total loss. That's after I worked on cleaning injectors, cleaning and changing plugs, and had fuel injection OHed. After each step, such as cleaning injectors, problems would disappear for awhile.

I now have no injectors and life is good.

Your carburetor is equally subject to sudden failure if the main jet were to become blocked.  Fuel sealant on the drain plug is past all screens and filters.

Clarence

[Guitarmaster]

Your carburetor is equally subject to sudden failure if the main jet were to become blocked.  Fuel sealant on the drain plug is past all screens and filters.
Clarence

Yep! Had a friend with a Varieze have a forced landing after the jets got plugged with rust bits from a drain plug I think. Forced landing on a narrow, country road during the Airventure Cup race. The party started at 1000AGL.

Sent from my XT1585 using Tapatalk

[TB_M20E]

This exact thing was happening to my '71 M20E.  Turned out that I had two cylinders with piston rings that were toast, causing the spark plugs to fowl with oil.  I'm having the cylinders rebuilt now.  I hope you figure out what is happening with your soon!

[neilpilot]

On 5/9/2017 at 2:46 PM, Cyril Gibb said:

In the winter (typically 6 months in Canada) I often end up flying at night in IMC.  My #1 fear is total, sudden engine failure.  As a possible help in the future for others, what were the early symptoms and what was the internal fault that finally blocked fuel?

Currently sailing off Menorca with infrequent internet so just read your post. Look at last line in NTSB report for N1310W, July 2012. Pices of a torn o-ring. Early symptoms were sudden roughness and/or significant loss of poster, usually on departure but once on arrival.