AFP FM-150 vs. FM-200A injection on 180hp 340

[GravityKnight]

Ready for a test run tomorrow to see if it really was an intake leak!

Pretty let down with JPI. The tach function on my 350 is dead. Not the connector, tested it thoroughly, not the lightspeed. Not the pins on the back (that I can tell). Just reads zero... I had a new FDS tach in a box, got it out, hooked it up and I have RPM again. Lame that it died after a couple months!

 

[bcone1381]

Are you familiar with SDS Oring sealed induction tube kit? Go to the link (aircraft) below and scroll down a little ways. The kit deals with the induction tube flange and the rubber hose/clamps. The constant tension clamps are very sturdy.

Aircraft

 

[GravityKnight]

Well, this sucky saga continues unfortunately… And it’s really strange and throwing me a curveball. I ran in on the ground, everything seemed fine, so I went ahead and flew it… For about 30 minutes I had no missing or issues and then the problem started back again under light throttle/idle.

When everything was running normal, my egts were still pretty tight at idle… once the issue reared it’s ugly head, now my egt’s have a larger spread at idle… Cylinders two and four are leaner than one and three by about 150+ degrees. When it is working correctly, they are more like 40 or 50° max spread at idle..

Under higher power settings. They are still really tight at 20 to 30° spread regardless of whether this issue is happening or not at low power.

Egt’s don’t change a whole lot when i switch which ignition im running on, still leaner on 2 and 4.

When I have it just sitting there, idling, it’s periodically misfiring, and I’m getting some puffs of black smoke here and there when it happens. Playing with mixture doesn’t really change it much until getting so lean it will barely run in general.

I was really pretty convinced that I had some intake leaks, but that doesn’t appear to be the culprit… Or maybe it still is?

Since this problem started, I changed the gaskets between the intake, pipes and cylinder heads, and this time I put a little bit of sealant on them. I also added a second set of clamps on the rubbers going to the sump, just to test with until my new constant torque clamps show up (which they have not yet.) I see no signs of anything that points to an intake leak anywhere on these pipes now! But it’s strange… Because it worked for about 30 minutes of flying before anything happened. That would probably make somebody think it’s heat related and that maybe the ignition system or something with the fuel system is getting hot, and that is what’s causing the issue. But when this problem first started the other day, I pulled the cowl off, let the engine cool down, changed the spark plugs and messed with a few other things and then took it back outside and started it… Everything had cooled off and the issue was there immediately. So I don’t think it’s related to something getting heat soaked… But who knows?

I have done extensive test on the ignition system and everything checks out with a meter properly, I have spark jumping between the posts on the coil packs as it should, never misses a beat.. trigger gap is set properly, and everything else I could troubleshoot via the paperwork checked out.

The only thing I have not done yet because I ran out of time was pulled the injectors out of the cylinder s, put them in cups and do the flow test to see if the flow divider is sending out even amounts of fuel. Even though at wide open throttle, it seems to be very even, I’m still gonna do this test and see if it shows anything, because with the EGT’s being so far off now at idle it’s either still got an intake leak, or it’s not flowing fuel evenly is all I can think…?

Open to other thoughts for sure!

 

[GravityKnight]

Are you familiar with SDS Oring sealed induction tube kit? Go to the link (aircraft) below and scroll down a little ways. The kit deals with the induction tube flange and the rubber hose/clamps. The constant tension clamps are very sturdy.

Aircraft

I have seen those, i would love to have them!! Looks like the way to go.

Looks like I would have to cut my intake pipes and weld them back to get the setup on there? (Since these superior pipes flare out larger on the sump side). I can tig, so it’s not out of the question and maybe ill have to go down that path before it’s over…

 

[stewartb]

The SDS tubes are similar to Lycoming except the o rings at the heads instead of gaskets. No big deal. Certainly no advantage over what you have.

Interesting problem.

 

[stewartb]

Your description sounds like you’ve experimented with you lean control. Have you tried adjusting the idle mixture at the servo?

Honestly, I’ve never looked at EGT at low power settings. Don’t care what they say. I’d try to eliminate the misfire. My idle mixture was rich. On my first flight the engine quit when closing the trottle during landing. Too lean would be easier to mask since you prime to start.

Where exactly are you tubes stained? It would be nearly impossible for fuel to stain the tubes. The intake pipes on the sump, maybe. If you have intake leaks the likely place would be at the intake gaskets on the cylinders. Warped flanges? Again, unlikely. A cracked casting on the left (2-4) side? I sure hope not.

Pics added for guys not familiar with this sump and servo.

 

[GravityKnight]

I have not adjusted the idle mixture arm on the 200a yet.... was thinking about playing with it. I have a wideband o2 sensor on my #3 cylinder so I can quickly set the air fuel ratio I want. Nice when looking for max take off power. Handy to make adjustments across the board. Mine seems to be close.. as in, when I have the mixture pulled out for max take off power at this altitude, the idle mixture is in a pretty good place as well. When everything has been "right", I lean for cruise efficiency, and then back to the spot where it makes max power and is also happy at idle etc. So not a lot of movement needed to achieve all the things.

What is throwing me off is there has been times where it was running well, tight egt's, no missing etc. down low, and then whatever happens, happens. Can't quite wrap my head around it now. Really sounds/feels/acts like a leak. When I popped the top on the flow divider the other day, and let some fuel run through it to see if there was debris or something, some fuel was trickling down the injectors and then ran down the intake tubes and at the bottom of the rubbers, fuel/oil stains came out on two. I thought this is it! Yesterday, after it started running weird again, I let some fuel run down those tubes to see, and no stains. (I drained the fuel out of the sump through one of those plugs).

I do need to rig up a vacuum or something to test better for intake leaks though, that was just a quick test to see if the same issue still was there.

One thing that is odd, remembering back to when I installed the sump and tubes... the #3 cylinder tube was too long. It was hitting the sump and not letting it lay flat on the cylinder. I had to trim 1/8" off the tube which I carefully did, then cleaned it up and washed it out etc. I may remove all the tubes, take the rubber couplers off, and bolt them back on without to see just how close the tubes are to the sump. I'm 99.9% sure none of the tubes were hitting the sump when I bolted them on after trimming that one.. but now I would like to see it with the couplers out of the way.

I've had the issue right after starting, with the cowl off, so not like fuel lines are getting too warm and boiling the fuel. I drained some fuel out of the system, no water, been over and over the ignition, and unless it's an issue effecting both boxes/triggers etc. that seems to not be the issue. Not sure how the flow divider could be causing an issue only down low, but I don't quite understand how it distributes fuel as evenly as it does.... so I will do the test on that next.

I've seen the difference in egt at low power when it's happy vs. pissed off. Got to track down why that is happening. Unfortunately, I have not run it long enough to know if the 2 leaner cylinders are hotter than normal egt temp wise, or if the two rich cylinders are richer than normal (extra fuel vs. intake leak). But when it's working right the egt's are so amazingly close from idle to WOT so this is trying to tell me something haha....

Sorry I'm rambling again, thank you for the pictures and advice.

 

[skywagon8a]

Since you are always operating at an altitude which requires leaning, it is important that you know the mixture relationship between the cylinders. It is possible for you to have one or more cylinder which are running very rich at the same time you have one or more cylinders running very lean. You need to read this and perform the tests to learn where the mixture relationships between your cylinders lie. https://airflowperformance.com/wp-content/uploads/2015/12/Nozzle-Tuning-Instructions.pdf
The exact EGT numbers and their relationship with the other cylinders mean nothing. There are no limits. By performing the above test you will learn what the peak EGT number will be for each cylinder. If you find one or more cylinders arrive at their individual peak EGT at a considerable difference in the mixture control position, you should talk to Airflow performance about setting up the proper orifice size for each of your cylinders. After doing that, see if your current complaint disappears. They modified my injectors with very satisfactory results. Talk to them.

An induction leak on a fuel injected engine will not effect the fuel/air mixture ratio, since the fuel is mixed with the air at the cylinder intake port.

 

[stewartb]

An induction leak on a fuel injected engine will not effect the fuel/air mixture ratio, since the fuel is mixed with the air at the cylinder intake port

If that’s true, why do we use sealed induction tubes?

 

[skywagon8a]

If that’s true, why do we use sealed induction tubes?

To distribute the air from the throttle valve to the cylinders in a fuel injected engine. If the engine had a carburetor, then an induction leak would effect the fuel/air ratio.

 

[stewartb]

No. Because fuel delivery is proportioned by air through the servo.

 

[GravityKnight]

Since you are always operating at an altitude which requires leaning, it is important that you know the mixture relationship between the cylinders. It is possible for you to have one or more cylinder which are running very rich at the same time you have one or more cylinders running very lean. You need to read this and perform the tests to learn where the mixture relationships between your cylinders lie. https://airflowperformance.com/wp-content/uploads/2015/12/Nozzle-Tuning-Instructions.pdf
The exact EGT numbers and their relationship with the other cylinders mean nothing. There are no limits. By performing the above test you will learn what the peak EGT number will be for each cylinder. If you find one or more cylinders arrive at their individual peak EGT at a considerable difference in the mixture control position, you should talk to Airflow performance about setting up the proper orifice size for each of your cylinders. After doing that, see if your current complaint disappears. They modified my injectors with very satisfactory results. Talk to them.

An induction leak on a fuel injected engine will not effect the fuel/air mixture ratio, since the fuel is mixed with the air at the cylinder intake port.

My EGTs had a large spread on the carb, to now a very small spread on the injection (when it's running right). I understand the point behind the test to get real data about the mixture differences between cylinders, as there are many reasons the EGT numbers are not accurate when compared to each other directly, but it's very obvious the mixture is much closer with injection vs. the carb right off the bat. When it's happy, the spread is very low, when it starts running poorly at low throttle, the EGT spread opens way up from 1/3 vs cyls 2/4. Fine tuning the injectors isn't going to fix whatever is causing this issue that has come and gone now. If it had been this way since first start, I would agree that it may need some adjusting, but when it's right, it runs really well.

If I can get this issue solved, then I will definitely perform this test and see what fine tuning it needs. There is something causing a very obvious change. I got a few hours of it all working correctly after installing the injection, and about 30 min yesterday before it went haywire again.

It's like a switch is flipped.. it goes from smooth, even egts, when I advance the throttle quickly with it already leaned for peak power on a climb it revs up smoothly... once this happens, it starts periodically misfiring, sometimes a little puff of black smoke, big egt spread, can't advance throttle without it stumbling (have to richen mixture or move throttle slower) etc. Once its rev'd up, it runs fine, EGT spread is tight, max power is there (same rpm on climbout) But down low it's not happy.

 

[skywagon8a]

No. Because fuel delivery is proportioned by air through the servo.

Yes it is...but it is injected and mixed in the cylinder's intake port. Each cylinder is only going to draw the same amount of air on each stroke whether it goes through the servo or an induction leak. The fuel/air ratio will not be effected.

 

[stewartb]

That makes no sense. I doubt an induction leak is the cause of this problem but I welcome you to test your theory by removing one induction tube and seeing how it affects how your engine runs.

 

[skywagon8a]

My EGTs had a large spread on the carb, to now a very small spread on the injection (when it's running right). I understand the point behind the test to get real data about the mixture differences between cylinders, as there are many reasons the EGT numbers are not accurate when compared to each other directly, but it's very obvious the mixture is much closer with injection vs. the carb right off the bat. When it's happy, the spread is very low, when it starts running poorly at low throttle, the EGT spread opens way up from 1/3 vs cyls 2/4. Fine tuning the injectors isn't going to fix whatever is causing this issue that has come and gone now. If it had been this way since first start, I would agree that it may need some adjusting, but when it's right, it runs really well.

If I can get this issue solved, then I will definitely perform this test and see what fine tuning it needs. There is something causing a very obvious change. I got a few hours of it all working correctly after installing the injection, and about 30 min yesterday before it went haywire again.

It's like a switch is flipped.. it goes from smooth, even egts, when I advance the throttle quickly with it already leaned for peak power on a climb it revs up smoothly... once this happens, it starts periodically misfiring, sometimes a little puff of black smoke, big egt spread, can't advance throttle without it stumbling (have to richen mixture or move throttle slower) etc. Once its rev'd up, it runs fine, EGT spread is tight, max power is there (same rpm on climbout) But down low it's not happy.

Have you looked inside the injector nozzles? Sometimes a tiny hair like obstruction gets in there causing fuel flow disruption. If you hold the nozzle up close to your eye looking towards some light you can sometimes see these things. I know it's a small hole and it takes some patience and concentration, it is possible to see in there. It wouldn't hurt to blow out the injection lines... just because. I have found a spec of rubber in one of the flow divider ports also. The fact that your situation appears erratic indicates it could be a spec of something. Have you looked at the inlet finger screen in the fuel servo? That's the least likely source of your issue. If there's something there it could be a clue.

 

[skywagon8a]

That makes no sense. I doubt an induction leak is the cause of this problem but I welcome you to test your theory by removing one induction tube and seeing how it affects how your engine runs.

Try it on your engine and report back.

 

[stewartb]

Respectfully, I’m not the one making such a silly claim. My engine costs more than I care to replace and I’ll keep my induction tightly buttoned up, as it’s designed to be.

GravityKnight, I look forward to hearing more about this as you dial it in.

 

[supercub83a]

Wouldnt an induction leak raise the manifold pressure causing more air molecules per volume to enter the cylinder and therefore leaning the mixture since the throttle body sets the fuel flow based on throttle position and airflow through it? Seems like it would cause a lean condition in an injected engine.

Hows your exhaust flame arrestor? Something rattling around in there intermittently blocking that exhaust?

Did you check the idle mixture just to eliminate that variable?

 

[GravityKnight]

Wouldnt an induction leak raise the manifold pressure causing more air molecules per volume to enter the cylinder and therefore leaning the mixture since the throttle body sets the fuel flow based on throttle position and airflow through it? Seems like it would cause a lean condition in an injected engine.

Hows your exhaust flame arrestor? Something rattling around in there intermittently blocking that exhaust?

Did you check the idle mixture just to eliminate that variable?

Yea an air leak would lean out the mixture... question is how much on a certain cylinder vs. the others depending on where the leak is. Say, if I pulled the plug out of the bottom center of the superior intake vs. a leak up on one cylinder where the intake pipe seals to the cylinder... how would that vary the mixture on that one cylinder vs the rest etc.

I don't have any flame arrestors or mufflers with this rv-4 style individual straight pipes. Good question though. Have to think outside the box on this one for sure so I appreciate those type of questions!! it very well could be something else causing this and I'm looking in the wrong place

I have not played with the idle mixture arm on the injection yet, only because at times it has run so well and the same amount of leaning on the mixture control for take off power also set a nice air fuel ration at low throttle... until it wigs out and two cylinders are going lean (or two are going rich - not sure which way it is yet, but 1/3 and 2/4 egts will be way off from each other when it starts running weird, and when it was running nice they were very close together). Thing that throws me off is if I rev it up and put a load on it, they all tighten up again and it runs strong when wide open.... weird.

 

[stewartb]

There’s no risk in adjusting idle mixture. Pay attention to how many turns you move it. You can always return it to where it is now. Forget about the EGTs and focus on eliminating the misfire. If you can see exhaust (black) smoke at idle, it’s too rich.

After priming and starting an observer may see raw fuel spray out of the pipes. Use that to gauge your priming routine. Reduce the raw fuel.

 

[GravityKnight]

I'll give it a try, but it only puffs on 1 or 2 cylinders, right when it misfires. Not hazing smoke. I've played with the mixture control at idle and it misfires regardless of position and I can lean until cut off, or richen enough it loses a lot of rpm and my wideband o2 says it's starting to dip into the upper 9.X:1 air fuel ratios. But it has also run just fine at these same settings with no egt spread, no puffs of smoke, no misfires etc.

Same on low throttle descents.... first few hours before the issues, it would come in smooth, now when in that situation, it pops sometimes, can feel the misfires as a momentary power loss. Doesn't matter where I put the mixture knob, it does it. I can see where idle mixture adjustment could help with fine tuning and alleviate having to move the mixture as much, but if I'm moving the mixture around and it does it regardless I feel like it's something else? Maybe I'm missing something on that thought process though.

And I keep going back to when its right, egt spread is gone, when it's unhappy, 1/3 were 180 degrees cooler than 2/4 at idle. And it seems to be pretty linear that the further I open the throttle and increase load, the tighter that spread gets until at WOT it was back to basically 20-30 degrees, and also running strong with no misfires etc.

 

[gahi]

I've had a high EGT from an exhaust flange leak.

also, had super intermittent issues from a leaking seal around a shaft. Have you checked all the gaskets from the throttle body/adapter/sump?

 

[supercub83a]

An induction leak should be worse at idle since the pressure diff is greatest at idle. You could check that the injectors are spraying fuel, seems unlikely since it happens on multiple cylinders and you cleaned them. Ive never worked with your ignition system, can it vary timing on individual cylinders?

Had a friend that was experiencing something similar, it did the same thing on each individual mag so we figured that was unlikely, found that the carb float bowl, which had fretted some from a previous problem, wasnt sealing correctly and would intermittently allow some extra air in causing an rpm fluctuation. My guess is an intermittent air leak at certain engine vibration ranges. I would do the idle mixture check (25-50 rpm rise) and adjust as required though, it will eliminate one variable even if it seems unlikely.

 

[GravityKnight]

All good ideas folks, I thank you for that. I will give the idle adjustment some love...

I've had a high EGT from an exhaust flange leak.

also, had super intermittent issues from a leaking seal around a shaft. Have you checked all the gaskets from the throttle body/adapter/sump?

Interesting point. I've poked around the TB, but maybe a closer look would be a good idea.




Tomorrow I'll be home again and can work on it. I picked up some clear measuring cups today so first thing I'll pull the injectors and do the flow divider test to see how much fuel each injector is flowing. If it passes that test, I'll play with the idle mixture and see what effect that has.

An induction leak should be worse at idle since the pressure diff is greatest at idle. You could check that the injectors are spraying fuel, seems unlikely since it happens on multiple cylinders and you cleaned them. Ive never worked with your ignition system, can it vary timing on individual cylinders?

Had a friend that was experiencing something similar, it did the same thing on each individual mag so we figured that was unlikely, found that the carb float bowl, which had fretted some from a previous problem, wasnt sealing correctly and would intermittently allow some extra air in causing an rpm fluctuation. My guess is an intermittent air leak at certain engine vibration ranges. I would do the idle mixture check (25-50 rpm rise) and adjust as required though, it will eliminate one variable even if it seems unlikely.

The ignition can't vary timing to individual cylinders, just overall it varies based on manifold pressure and rpm. There are some neat things about this system, and also some things that I don't care for. I wish I had control over the timing tune like you can with a flyefi system. Guarantee there is a bit more power and efficiency to be had if I could tailor the timing to my exact setup. I have heard of some people having issues with this system, but overall I think they work well from what I gather. And even if there is a bit left on the table, it does make good power, and really does give good efficiency out of this engine. Even with a carb, I could pull it back to about 102mph indicated airpseed at 8800ft (so pretty good TAS) and was burning 5.3 gph! wow! (These BLT's are pretty clean for a bird with long suspension travel and 31's and 28mph stall etc., so a lot of it is the airframe of course...but still I have been blown away with efficiency of the setup)

 

[stewartb]

How did you buy the FI? New? Did API set it up for your engine and altitude? If no, and it’s set to average conditions, wouldn’t you expect it to require adjustments to suit your conditions? A rather small displacement for that servo and at higher than average altitude? Superior set mine up for my IO-400 when it ran on the test stand but required adjustment for the Alaska climate. You really should take a few minutes to try to find your engine’s sweet spot idle mixture.

 

[GravityKnight]

I did work directly with Don on this setup (new). He had all parameters of my setup and altitude. He said the last ~25% of the throttle wouldnt do much because the 200a would be flowing enough for max power by the time it’s 75% open, and that the throttle would be a little touchy overall, but the larger unit would make more power at high altitudes and otherwise work fine so I went for it. I extended my throttle handle to make it less touchy and that has worked well as far as that goes. The last 20% before WOT doesn’t have much effect as he said.

 

[GravityKnight]

Update:
Had time to do a few things today. Could not make a test flight due to very poor weather (again... this winter has been tough).

Pulled the injectors and hooked them up and put them in measuring cups. Ran the system at different throttle settings as that does vary how much fuel comes out even with it not running. Tested about 3-4 times and the results say the flow divider is working as intended. There was very small variations in the cups, but I would estimate only a few 1% difference in output... not enough to explain issues with 1/3 and 2/4 having a large egt spread etc.

Ok... decided to move on and run it and adjust the idle mixture control.

After doing this I will say I was wrong about the mixture control (pilot mixture control in the panel) having as much effect at idle as I thought. I watched the wideband o2 and egts close today while adjust that and it has little effect, and then in a very short span it starts to lean, then you hit lean cut off. So too coarse down low to really rely on. So good advice from stewartb and some others about dialing in the mixture control.

I'm not sure if the issue has been eradicated until I can fly it and really put it through the paces and get everything heat soaked etc., but I do believe progress was made today after I spent 45min running it in the cold, freezing to death, making adjustments!!

What is interesting about the idle mixture control is that it has a strong effect on mixture up to around 1400rpm! It was a balancing act as dialing in the mixture to the exact place I wanted it at say 900 rpms, it would be a little lean at 1400... so I just played with it until it seem to run pretty well from about 800 rpms up. Below 750-800rpms it still gets a bit wonky. The egt spread opens way up, and it doesn't run as smooth... though it wasn't noticeably misfiring and puffing occasional smoke either... so still an improvement. Once I hit around 800 or so rpms... the egt spread tightens to 30 degrees, and it runs well. I tested at a lot of different rpms and it was running pretty well. Flight test will be the real story.... weather might allow that on friday. Will post back more at that time....

Thank you all again for the suggestions, ideas, etc.!

-Todd

 

[GravityKnight]

Hoping to fly more this weekend, or monday at least looks decent. Flew it a little last night. It's better, but it's still a little off and I just can't quite wrap my head around it. Coming in to land twice it seemed quite a bit better as far as not misfiring or losing momentary power to the point you could feel it. Idle did seem to degrade as I sat there for a few min checking different RPMs. Seems it may have heat soaked some fuel lines or something because it started to run kind of crappy while idling, I rev'd it up for a while to get fuel through it faster, and that seemed to clean it up for a little bit after that. I know this can happen with this mechanical injection but it's going to be a pain. It was 23 degrees out last night when this was happeneing. So a hot day I'm a bit worried this will surpass the annoying stage.

I may need to tweak that mixture a bit more, I may have it a bit too lean now. Overall though, it does seem better. It's just weird because at real low idle the EGT spread does open up and it starts to run crappy when all this happens at once. The other day, it did not do this with the cowl off. So I'm wondering what is getting heat soaked exactly. I all my fuel lines are covered in fire sleeve and routed as "cool" and short as I could get them.

 

[GravityKnight]

So I've flown it a few times after making the idle adjustment. I had to go back in and adjust it some more, I had it a little too lean. But it's still not fully happy. I have played with that mixture and found what appears to be the "best" mix, but something is still off.

That idle mixture controls the mixture all the way up to about 1400rpms where it transitions out. I just can't get it right for both low idle, and 1300rpms... from what I can tell, it's not popping anymore whether on the ground idling or coming in to land at idle or low power. That is good. The large momentary surges are a lot better too. But it still runs kind of rough down at lower RPMS... and it's just not right. No idea, but the carburetor shouldn't run noticeably smoother than fuel injection with a close EGT spread. That just seems all wrong. I just emailed Don at AFP again to update him and see if he has any other ideas....

Thanks all,
-Todd

 

[skywagon8a]

Seems it may have heat soaked some fuel lines or something because it started to run kind of crappy while idling, I rev'd it up for a while to get fuel through it faster, and that seemed to clean it up for a little bit after that. I know this can happen with this mechanical injection but it's going to be a pain. It was 23 degrees out last night when this was happeneing. So a hot day I'm a bit worried this will surpass the annoying stage.

This is something I would expect in the summer. Since you are at a high altitude, it may be more noticeable at lower temperatures. It's an indication of low fuel pressure at idle. Turning on the auxiliary fuel boost pump makes it clear up. Does your engine pump have a pressure adjustment? If so, increase the pressure.