GAMI Fuel Injectors

[carusoam]

Great follow-up Will!

Not sure about the rpm rise exactness…

Let’s invite @kortopates to the conversation…. (Rpm rise during shutdown question, M20K)

Best regards,

-a-

[A64Pilot]

The RPM rise on shutdown is a way to measure idle mixture, I believe it’s to ensure the engine doesn’t stumble on throttle increase like it could if it was too lean.

It should be easy to adjust and not mess with other settings, as to whether you should I guess the only answer is that it’s not within specs so yes you should.

Is the field elevation where you are now significantly different than where the adjustments were made?

[kortopates]

I think that is my problem now. I got my fuel pump throttle body and spider overhauled and tested all together on the bench at the shop. When we installed it back on to my airplane i have this new problem of dying in the turn. So it’s going back into the shop next week and they are going to put a pressure meter on it to see what my idle pressure is set at. Will report what he finds. Also today did an inflight induction leak test and noticed 6# cylinder had the lowest change in egt from  32” down to 20” map. The other 5 cylinders dropped 165 to 200 degrees while #6 dropped only 140 degrees. So will do the soapy bubbles check around cylinder #6 and hopefully find some bubbles. 

was one your MAP settings equal to ambient atmospheric pressure? If not you don’t have a control. We usually call for turbo’s to be done down low at 3-5K setting MAP to ambient for control (25-27”), then reduce by 10 inches. The 140 vs 165-200 is not significant either.

On the idle cut off rise, only 10 rpm is bit lean. Doesn’t have to be 50 though. IIRC TCM calls for 20-50 rpm rise at minimum idle RPM and with a fully warmed up engine.


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[Aspen2013]

Now we have the GAMI injectors exchanged and the LOP FF are within .5 gph difference or less from richest to leanest cylinder. Still have engine stall in the turn while taxing  Right or left. Tried low BOOST pump and then lean with mixture knob. That doesn't work. You have to lean so far to counter the increased flow that the fuel basically is cut-off.  If you turn at 1000 rpm or greater that seems to keep it going.  With hot engine idle RPM will be around 850. when it is cold you can be 770 or lower but the engine will not stay running anyway. Not sure why Mooney service manual page 71-00-51 references making idle fuel pressure (9 psi) adjustments at 650 RPM??.  POH says after start RPM should be 900-1000. Sometimes taxing is a little fast with 1000 RPM. The worst part is upon landing on short final and reducing engine to idle and it starts that stumbling before you land. That is nerve racking.  As we all know you are landing long if you don't get that speed down.  In order to not worry about engine quitting I leave throttle a couple turns in from idle. MAP 10 or more. it keeps speed up a little more than before. Anyway Next step is getting with mechanic to check fuel system pressures and such. It is just strange that everything was fine until the injectors were switched from tuned TCM to GAMI. 

MY FIELD ELEV is 6800'

When at idle and mixture is leaned to max RPM on the ground usually see 20 +/- 10 on RPM rise

 

Does anyone have a recommendation on where they set the minimum idle RPM on warm engine for TSIO 550 (G)?

Edited September 19, 2022 by Aspen2013
add info

[Will.iam]

I say keep working with the a&p to get the pressure right with rpm at 650. My A&P had ti readjust the idle stop then once i got to 600 he adjusted fuel pressure then air fuel mixture in that order and when that last step was done it was amazing the difference in how the engine ran. I wouldn’t have believed it if I hadn’t been there to see it for myself. I’ve only got two flights with 6 turns after landings but my confidence in the engine not stalling or quitting in turns went way up. As it hasn’t done any stumble since the adjustments. 

[A64Pilot]

Aspen,

If your field elevation is significantly different than the elevation your mechanic set the idle mixture, that could explain the difference.

However if your only getting a 10 RPM rise at a field elevation of 6800, I’d richen it up a little as when you go to sea level it might be very lean.

Wow 6800, yeah I know why you got a turbo

I’m not familiar with the procedure to comment much, but I know setting fuel pressures in those motors is both a pretty involved and complex procedure, requiring gauges and hoses I don’t have.

I’d say find someone that specializes in the procedure and have them perform the complete procedure.

[Fly Boomer]

7 hours ago, Aspen2013 said:

Anyway Next step is getting with mechanic to check fuel system pressures and such

All mechanics are not created equally.  Continental fuel injection systems are a wonderful thing under most circumstances, but setup requires specialized knowledge, experience, and tooling.  The instructions used to be in SID 97-3, but have now been incorporated into the M-0 document.  You can find old versions of the SID on the internet, but I have not found the M-0 document.  I believe the latest rev of the SID before it went to M-0 was "G" (SID 97-3g).  I don't know if changes to the procedure were incorporated into the M-0 document.

BOTTOM LINE:  If your mechanic is not intimately familiar with these engines, or doesn't have experience setting up their fuel system, or doesn't have the tooling, or doesn't have the M-0 document, you are probably wasting your time and money.

http://pceonline.com/wp-content/uploads/2017/04/SID97-3GFuelSysSetUp.pdf

EDIT:  Found a copy of M-0 at:

https://www.csobeech.com/files/TCM-StandardPracticeManual.pdf

BUT, even though M-0 says it has incorporated SID 97-3g, I don't see all the material that was in the older manual.  Maybe @M20Doc will weigh in on where the contents of SID 97-3g went -- he always seems to have the appropriate documentation for all occasions.

[Guest]

One needs accurate gauges, and all of the service documents, all of them should be similar procedures. The Mooney manual, if different is the final say.

In a nut shell, warm the engine, set the idle un metered fuel pressure at the specified idle speed, set the idle mixture for the correct shut down rise.  This should be a setting that allows for smooth idle operation, and rich enough that the engine will accelerate from idle smoothly with no stumble.

Next is max power adjustment, but with this the engine must make rated boost and rated RPM first, both effect fuel flow.  Max power fuel flow is set with either a known accurate flow transducer or by checking metered nozzle pressure.  If full static RPM can’t be obtained on the ground there is a calculation made to set the flow at a lower value relative to the under speed of the engine.  
 

When adjusting max power fuel flow, you have to go back and check idle fuel pressure at the correct speed, sometimes it takes several attempts to find a balance.  Generally lower idle unmetered fuel pressure is desired.

Its not a difficult process it just takes time.  Some will make the adjustments with the engine running, some do the start and stop method.

[N231BN]

4 hours ago, Fly Boomer said:

BUT, even though M-0 says it has incorporated SID 97-3g, I don't see all the material that was in the older manual.

It is frustrating now because the information that was in one document previously is now in three different sections in M-0.

[Fly Boomer]

34 minutes ago, N231BN said:

It is frustrating now because the information that was in one document previously is now in three different sections in M-0.

I don't see all the information in SID 97-3g represented in the M-0 I linked to above.  Is the copy of M-0 I linked to above complete?

[N231BN]

2 minutes ago, Fly Boomer said:

I don't see all the information in SID 97-3g represented in the M-0 I linked to above.  Is the copy of M-0 I linked to above complete?

No, that's a revision copy.

[N231BN]

12 hours ago, Aspen2013 said:

Now we have the GAMI injectors exchanged and the LOP FF are within .5 gph difference or less from richest to leanest cylinder. Still have engine stall in the turn while taxing  Right or left. Tried low BOOST pump and then lean with mixture knob. That doesn't work. You have to lean so far to counter the increased flow that the fuel basically is cut-off.  If you turn at 1000 rpm or greater that seems to keep it going.  With hot engine idle RPM will be around 850. when it is cold you can be 770 or lower but the engine will not stay running anyway. Not sure why Mooney service manual page 71-00-51 references making idle fuel pressure (9 psi) adjustments at 650 RPM??.  POH says after start RPM should be 900-1000. Sometimes taxing is a little fast with 1000 RPM. The worst part is upon landing on short final and reducing engine to idle and it starts that stumbling before you land. That is nerve racking.  As we all know you are landing long if you don't get that speed down.  In order to not worry about engine quitting I leave throttle a couple turns in from idle. MAP 10 or more. it keeps speed up a little more than before. Anyway Next step is getting with mechanic to check fuel system pressures and such. It is just strange that everything was fine until the injectors were switched from tuned TCM to GAMI. 

MY FIELD ELEV is 6800'

When at idle and mixture is leaned to max RPM on the ground usually see 20 +/- 10 on RPM rise

 

Does anyone have a recommendation on where they set the minimum idle RPM on warm engine for TSIO 550 (G)?

Your engine should idle just fine at 650 RPM. Save those brakes!!

[Guest]

2 hours ago, Fly Boomer said:

I don't see all the information in SID 97-3g represented in the M-0 I linked to above.  Is the copy of M-0 I linked to above complete?

Access to the Continental library as provided by ATP, costs me $1000 US per year.  Lycoming is the same through ATP.

[Fly Boomer]

58 minutes ago, M20Doc said:

Access to the Continental library as provided by ATP, costs me $1000 US per year.  Lycoming is the same through ATP.

Do you get a better deal from ATP than continental.aero?

[Guest]

4 hours ago, Fly Boomer said:

Do you get a better deal from ATP than continental.aero?

There are no deals with ATP.  I budget $1000 per year per airframe model we take care of, some ATP manuals are even more at $2000 per year, De-Haviland Beaver, PT6 etc.