IO550 idle issues

[Mufflerbearing]

A recent problem has struck my plane.  Especially when warm, the plane will not idle below 1000 rpm.  I can get it to catch when I hit the electric fuel pump, then it runs rough after a bit, shut it off and it will die.  There is no issue with any rpm or power loss above 1000 rpm.  When doing a mock emergency landing with my instructor, we pulled back to idle and it continued to run, probably from the windmilling of the prop.  This does make for an issue while taxiing as you can imagine. 

I do not have a fuel pressure gauge on the dash so I don't know the pressure at idle. 

Ideas?

[flysamo]

we had the engine shut off when we tried to run at low idle  speed, traced problem to fuel injection on IO 550, had unit rebuilt and problem with idle and leaning on the ground went away.

[Mufflerbearing]

We are thinking the fuel injection idle circuit. 

[StevenL757]

7 hours ago, Mufflerbearing said:

A recent problem has struck my plane.  Especially when warm, the plane will not idle below 1000 rpm.  I can get it to catch when I hit the electric fuel pump, then it runs rough after a bit, shut it off and it will die.  There is no issue with any rpm or power loss above 1000 rpm.  When doing a mock emergency landing with my instructor, we pulled back to idle and it continued to run, probably from the windmilling of the prop.  This does make for an issue while taxiing as you can imagine. 

I do not have a fuel pressure gauge on the dash so I don't know the pressure at idle. 

Ideas?

MB,

Have you had any Mx done recently?  When did the problem start?  If it happens all the time, likely culprit is your fuel pump.  Otherwise, it could be...

* Low-end fuel pressure setting

* Idle mixture too lean

* Fuel leak somewhere

Either way, have a mechanic knowledgeable with the IO550 platform look at the engine.   Try reproducing the issue for them during diagnosis and see if they come up with anything above.  Let us know what you find?

Steve

[Mufflerbearing]

3 minutes ago, StevenL757 said:

MB,

Have you had any Mx done recently?  When did the problem start?  If it happens all the time, likely culprit is your fuel pump.  Otherwise, it could be...

* Low-end fuel pressure setting

* Idle mixture too lean

* Fuel leak somewhere

Either way, have a mechanic knowledgeable with the IO550 platform look at the engine.   Try reproducing the issue for them during diagnosis and see if they come up with anything above.  Let us know what you find?

Steve

There has been no recent work done on the engine.  This problem has been recent, but I am not aware if it came on at once or gradually.  I'm thinking that it was more of a quick onset of symptoms. 

I had my mechanic look at it today and he will clean out the fuel screen and then  he will hook up a fuel pressure gauge and check idle fuel pressure.  He said that it needed to be between 8-10 psi. 

[M20S Driver]

I bought my plane in Florida and flew it to CA in winter.  I had idle issues where I had to add power to keep the idle alive at sea level in KPAO.  If I remember correctly, it was a simple mixture adjustment to make it richer per my mechanic.  

[Jim F]

9 hours ago, Mufflerbearing said:

A recent problem has struck my plane.  Especially when warm, the plane will not idle below 1000 rpm.  I can get it to catch when I hit the electric fuel pump, then it runs rough after a bit, shut it off and it will die.  There is no issue with any rpm or power loss above 1000 rpm.  When doing a mock emergency landing with my instructor, we pulled back to idle and it continued to run, probably from the windmilling of the prop.  This does make for an issue while taxiing as you can imagine. 

I do not have a fuel pressure gauge on the dash so I don't know the pressure at idle. 

Ideas?

One thing I would do before adjusting the fuel flows would be to pressure check the induction system.  Its more likely that a induction hose clamp is loose and at idle you're too lean.  Then verify low unmetered fuel pressure and idle mixture.  jim

[MB65E]

I’m not sure too many shops run the fuel system per the book during inspection. I used to have access to the FI box continental recommended.

Setting idle fuel pressure And max flow would change annually as the system. I would check the setup annually, or any time the engine ran differently. Super nice to have a good set of gauges. 
-Matt

[Guest]

To adjust the fuel system on a NA Continental engine you only need 2 very accurate pressure gauges for setting the unmetered fuel pressure at idle, and one to set the metered nozzle fuel pressure.  A turbo requires different gauges.

Clarence

[carusoam]

Expect if the engine is running at 1krpm at idle....

Landing long is going to be a challenge...

Typical idle rpm is written down somewhere... 6-700 rpm(?)

Time to review my own engine docs while we are at it...

Have you verified the working of the rotating knob?  If the vernier knob is working properly.... it will require being turned all the way counter clockwise to achieve minimum throttle position...

If you don’t use the vernier part... somebody else did, and you just found out... 

PP thoughts only, not a mechanic...

Best regards,

-a-

[Mufflerbearing]

My mechanic put in 1/8 turn rich on idle circuit just to get me by before setting up the time to hook up the fuel pressure gauges.  I'll report when I know more next week.  I appreciate the heads up and the ideas! 

[carusoam]

On 12/7/2019 at 11:43 PM, Mufflerbearing said:

My mechanic put in 1/8 turn rich on idle circuit just to get me by before setting up the time to hook up the fuel pressure gauges.  I'll report when I know more next week.  I appreciate the heads up and the ideas! 

Any update, MB?

All well?

Best regards,

-a-

[Mufflerbearing]

We put a pressure gauge on the FI system and it is just too low at idle.  He raised the pressure which we know is a band aid and will use the proper FI set up at annual.  It is working a little better.  I catch it when necessary which is not as often now.

[LANCECASPER]

I had this issue with an Ovation I owned and after all of the fuel flow adjustments it still stumbled on the ground. We put in new plugs and it was fine after that.

[Robert C.]

We have done everything described above...and I still need to make sure that after landing rpm don't drop below 950-1000 or it will stall. Sitting idling I can get it to the 900-950 range as long as I reduce very slowly and carefully.

I've given up, was spending too much on my A&P trying different things. Hope you have better luck

Robert

[philiplane]

There is no shortcut. You have to do Continental SID 97-3F to accurately set up the injection system. 

[StevenL757]

@Robert C., there’s no reason to give up.  This can be solved without pouring a ton of money.  I had the same issue with my previous engine. The SID 97-3F fixed it 100%.

[Guest]

9 hours ago, Robert C. said:

We have done everything described above...and I still need to make sure that after landing rpm don't drop below 950-1000 or it will stall. Sitting idling I can get it to the 900-950 range as long as I reduce very slowly and carefully.

I've given up, was spending too much on my A&P trying different things. Hope you have better luck

Robert

Your engine can be set to idle smoothly at much lower RPM.  In my experience TCM fuel systems suffer from maintainers not knowing how/ what to do, more than they suffer system failures.

Look for a PM.

Clarence

[PMcClure]

1 hour ago, M20Doc said:

Your engine can be set to idle smoothly at much lower RPM.  In my experience TCM fuel systems suffer from maintainers not knowing how/ what to do, more than they suffer system failures.

Look for a PM.

Clarence

I found the same thing - and had similar issues with my 550. 3 or 4 different A/P's could not correct it and all but one was unaware of SID 97-3F. I took it to TCM in Fairhope whom greatly improved the situation by doing the proper set-up. 

But ultimately, I had to rebuild the spider valve on top of the engine. New plugs and wires is not a bad suggestion either. I did all of that and have not had any issues since. 

[Guest]

With the help of my daughter I have up loaded an alternate Continental Fuel Injection set up procedure.  Hope that it’s helpful.

Clarence

[MB65E]

36 minutes ago, M20Doc said:

With the help of my daughter I have up loaded an alternate Continental Fuel Injection set up procedure.  Hope that it’s helpful.

Clarence

Neat!! With out the Continental gauges/box?

I’ve set up several tsio550s but I’ve always had the box. That airplane went away, sold the box. I’ve always stayed away from annuals on continentals because I no longer have the box. 
-Matt  

[Guest]

1 hour ago, MB65E said:

Neat!! With out the Continental gauges/box?

I’ve set up several tsio550s but I’ve always had the box. That airplane went away, sold the box. I’ve always stayed away from annuals on continentals because I no longer have the box. 
-Matt  

I’ve never had access to the TCM test box, they’re just too expensive.  All versions of SID 97-3 have shown adjustments with an accurate gauge set so that’s what I use.

The alternate method I posted helps as well.

Clarence 

[Mufflerbearing]

Just changed the oil and while reading this thread, a suggestion was to look at the plugs.  I looked through the engine log books and came to the conclusion that only one plug had been replaced.  Ever.  The engine has 1440 hours on it now.  I pulled the plugs and all of the original Champion Massives were so out of spec.  The closest one was the replacement Tempest plug that was at 1100 ohms.  The next closest was 35,000 and the rest went up from there.  11 out of spec out of 12.  Not sure how this plane flew.  I have ordered a new set of Tempest fine wires which will be in on Wednesday.  I am not sure that this will totally fix the problem, but I am sure that the engine will run much better overall.

[carusoam]

Awesome follow-up, MB!

Looking forward to the next one...

Best regards,

-a-