EDM-830 installed...troubling data

[par]

My C now sports an EDM-830 because I was tired of looking at the useless OEM cluster. At this point, there are several issues i'm concerned with and I need some MS expertise.

 

-The RPM reading in the EDM is incorrect between 400-800 RPM. The original gauge is pretty much spot on though. My IA believes this has something to do with the unit thinking it hooked to a 6-cylinder engine rather than a 4 cylinder. I have slick mags and the appropriate harness is connected.

-The FF on T/O was only around 13GPH. In cruise, it is shows between 8-9GPH, which is about right. I have read several threads that say FF on T/O should be closer to 17GPH. Clearly, the difference here is massive. I live at sea level and the altimeter was 30.8 with a OAT of around 58 degreed during the noted flight. I brought it up to the IA and I was told that it's not possible to get the exact fuel flow from a carbureted engine. Now, since my CHT's are also high on T/O, I'm starting to think my carb needs an OH.

-Finally, the CHT's are extremely high on T/O. My original mooney gauge used to show the CHT almost at 500 but that was not correct. First, the IA used a CHT probe that goes around the spark plug(on cylinder #3) and it showed the CHT to be at 460 on T/O on that cylinder!! The remaining cylinders were showing between 330-420 with #1 being the coolest. I remember reading how this location of the probe can show inaccurate CHT's. So I had him change that and use the designed spot on the cylinder for the CHT probe. Sure enough, the reading on #3 dropped by over 30 degrees. So, in reality, my hottest cylinder is the #3 cylinder and it showed a CHT of 430 on T/O today. This was at a climb speed of 130-140mph with the cowl flaps completely open. 

The doghouse is in good condition without any unacceptably large gaps or holes. My moony also has the LASAR addition on the original guppy mouth (picture attached). I am also attaching the data from my short flight today. 

Edited March 13, 2016 by par

[Guitarmaster]

What were your cruise CHT temperatures?

13gph does sound low. Mine is FI, but could it be an enrichment valve problem?

Sent from my XT1254 using Tapatalk

[par]

8 minutes ago, Guitarmaster said:

What were your cruise CHT temperatures?

13gph does sound low. Mine is FI, but could it be an enrichment valve problem?

Sent from my XT1254 using Tapatalk

Cruise CHT's were: #1: 332; #2: 348; #3: 378; #4: 351

[par]

2 minutes ago, daver328 said:

FYI ... Seems like we burn about 17 gph on takeoff. But my memory is not that sharp anymore. That is if your k factor is set correctly. It may take some flights and comparing actual used to JPI - before you can get it right?

K factor was set but I can't say if it is 100% correct. Since my cruise FF shows 8-9gph, my guess is that it was set correctly.

[Bob_Belville]

I'm not sure why you're showing 6 cyl. Is the JPI the correct model and programmed correctly? Not that that ought to affect your issues but it make me wonder. That and the installer telling you what seems to be patty cake explanations. Someone with a C can tell us for sure but I do not believe what he's telling you about FF and carburetors. Fuel injection is more even cyl to cyl but the FF sensor is only measuring total flow. It's possible the sensor is not installed properly... the tubing must be straight near the sensor. 

[Bob_Belville]

8-9 seems a little low unless you cruise at 65% power or below.

[Oscar Avalle]

Interesting, I am having a very similar problem. My CHTs are way to high on my JPI. I tried everything, I even got a new carburetor.

I start wondering if there is something wrong with the the installation of the probes. It does not make any sense that the CHTs are that high. 

[N601RX]

Make sure the ground wire to the unit is connected directly to the engine and not the airframe.  The slick mags have 2 holes that the rpm sensor can be screwed into.  It will only read correctly in one of them.  Can you post a picture of the fuel flow transducer mounting? 

[carusoam]

One oddity... FF.

Why is FF not exact for a carbed engine?

It is the same spinning wheel in the same fuel line before the engine.

Sure, there is a float in the bowl to add some complexity.  But really, spinning wheel in the fuel line is pretty accurate.  Get the K factor adjusted so that fuel used is accurate.  This may take a few iterations.

 

Two oddity... TC.

You are familiar with the legal issue on where the ship's gauge is supposed to be.  The JPI sensors go in three holes.  The fourth one has to piggyback with something.   either a spark plug or the ship's gauge CHT probe.  Using a spark plug ring probe was a good idea back in the day.  It is a bad location (up to 50°F high) and the sensor gets destroyed when the plugs get removed for cleaning.  Find a ring sensor that piggybacks with the ship's gauge.  JPI uses K type thermocouples.

 

Three oddity... Temps.

The square box dog house has been a poor airflow design from the beginning.  Cylinder cooling is very much dependent on air being delivered evenly to each cylinder. In the front out the bottom.  The whole Mooney community is looking forward to an updated airflow design for the C.

 

Four oddity...  EGTs

Carb fuel distribution is nowhere as even as four balanced fuel injectors.  No real way of adjusting it. One way to improve is using the throttle slightly closed to increase turbulance while shutting down the secondary fuel jet.

 

Fifth oddity....  Carb temp

Did you get the carb temp sensor?  Nice piece of information to have.  JPI makes it easy.

 

You now have one of the best instrumented M20Cs on the planet!

 

Does that help?

Best regards,

-a-

[par]

Just now, daver328 said:

The fuel flow for carbureted engines not being accurate ... Never heard that before? We just put an 830 in in June. We've got ours fairly (very) close on the conservative side. (JPI Shows just a little more burned than actual) I have noticed on short flights around the pattern after a long run-up (e.g. First few flights out of annual) it is not as acurate ... as on long cruise flights or pattern work. 

The only possible inaccuracy may be fuel,held in carb float chambers ... but that is only lag. 

It may be possible the "enrichment" function of the carb Hank refers to ... is not working? I can definitely see the the FF go down when I back off of full throttle just enough to see that MP Needle budge.  (Thanks Hank)

Is it possible to adjust the enrichment function without pulling the carb off or overhauling it?

[par]

6 minutes ago, N601RX said:

Make sure the ground wire to the unit is connected directly to the engine and not the airframe.  The slick mags have 2 holes that the rpm sensor can be screwed into.  It will only read correctly in one of them.  Can you post a picture of the fuel flow transducer mounting? 

I will bring that up to the IA. I will also get some pictures tomorrow.

[Hank]

Your welcome, Dave. Flying WOT vs. pulled back enough to make the MP needle move saves mucho fuel. I went 2.2 hours to Hilton Head on 18.2 gals.

Wish I could help here, but not having a monitor, I've not bothered looking closely at the graphs. I will say this about my 1970 C:  per the book, fuel flow at sea level, WOT/2700 is 18.2 gph.

 

Edited March 13, 2016 by Hank

[Bob_Belville]

The EGTs seem to be higher than I would expect if you're getting proper FF full rich. On TO I'd expect something like 300 ROP.

[carusoam]

Enrichment circuit...

there are two fuel jets in a Mooney carb.  The main jet is open all the time.  The secondary jet is open at full throttle.

Close the throttle slightly, closes the secondary jet.  The cocked throttle plate increases turbulence in the carb. Turbulence helps distribute fuel amongst the four cylinders.

Best regards,

-a-

[garytex]

Bellville has it right. Check the lines in and out. Look at takeoff EGT's see if they make sense vs indicated fuel flow. Bends in the line take the top off indicated FF at high flows. Also look for missing fuel at fill up. Maybe the missing 2 gallons is the unrecorded take off low indicated fuel flow. Some of the ways I puzzled my way through the same issue, albeit with less gauge under reporting.

"Fuel injection is more even cyl to cyl but the FF sensor is only measuring total flow. It's possible the sensor is not installed properly... the tubing must be straight near the sensor. "

Flowscan is the go to fuel flow meter in the marine world. They use multiple air bladder pulsation dampners with the exact same flow sensors JPI uses.  There needs to be a few inches of straight line in and out of the flow sensor.  We aren't going to carry around  the weight of the dampners so need to install per the directions. Or understand when and why the gauge is lying. 

 

[bradp]

fwiw I had one EGT that was always more finicky than all the others (fluctuations and a higher temp).  EGT depends on multiple factors including placement of the probe.  However in this particular circumstance is was corrected by moving the lock washer on the probe and harness terminals from behind the terminals to between them as specified in the JPI install manual (correct should be screw head, terminal, lock washer, terminal, nut).  Apparently this matters.  Take a look at probe connections.  Ensure that the probes are grounded to the engine ground.   Find a piggyback CHT for your number 3.  Then start working through this FF troubleshooting.  Also make sure that the FF is not mounted directly to another fuel competent.  There should be some hose in between,  as this will minimize the potential for cracks, and vibrations will not be transduced through the unit.  Agree with Bobs suggestion to look for bends in hose, verify proper orientation and k factor (which is printed on the transducer and needs to match the config of the 830).   There is also an RPM setting in the "deep settings"  that counts the number of pulses the unit senses and I think uses this as a factor to calculate the displayed RPM.  If your 830 is Saying 2250 instead of 2700 RPM, I'd check to make sure they this config is set to 4 and not 6.  I'm away from my manual but it's in there...  You can get an iPhone app that will  serve as a visual tachometer and you can test this (or rather have someone else test this) during a takeoff roll.  Also look for that for missing fuel as Bob had suggested.    

 

Not an A&P.  Frequently in trouble with wife for spending too much time in hangar.  

[Oscar Avalle]

Another issue that may affect your fuel flow at take off. Is your electrical fuel pump on? In my case it makes a big difference. 16 gph without electrical fuel pump 17.3 with fuel pump on.

[par]

So we have been able to troubleshoot and correct the issues. It took a call to help center to get all the values put in but things now seem to be working correctly. However, I do have a couple of questions for you guys who have been flying with these devices.

First, my plan is to run ROP and I have looked at the procedure in the instruction book a number of times now. I haven't actually had the chance to try it out yet but I plan to run it this weekend. Now, keep in mind that my knowledge on this subject is limited so my question may appear stupid. What values should I be looking at for my EGT/CHT if the engine is leaned out to a safe level? What is the absolute maximum EGT/CHT I should see by the time i'm finishing turning the mixture knob? Also, without getting into a long discussion on this topic, do any of you with a carbureted engine run LOP?

Second, my fuel flow is indicating properly at about 17.5 during T/O once the value is settled. The book recommends that several flights be flows while noting the amount of fuel used per the JPI and the actual amount used to refine the "K factor". Is this worth the effort?

Finally, for a 63c, can someone verify that total USABLE fuel capacity is 48gal with a tank capacity of 52gal? I ask because the POH does not explicitly state this info.

 

[Raptor05121]

On 3/14/2016 at 9:06 PM, Oscar Avalle said:

Another issue that may affect your fuel flow at take off. Is your electrical fuel pump on? In my case it makes a big difference. 16 gph without electrical fuel pump 17.3 with fuel pump on.

How is that possible? Doesn't the pump simply fill the bowl?

[mike20papa]

My electric fuel pump raises my fuel flow, also.  I installed my flow cube between electric pump and mechanical pump, so I think the extra flow from the electric pump is cycled/by passed thru the mech. pump.  Only so much fuel can flow past the float needle, so must be the explanation. 

[Marauder]

3 hours ago, par said:

So we have been able to troubleshoot and correct the issues. It took a call to help center to get all the values put in but things now seem to be working correctly. However, I do have a couple of questions for you guys who have been flying with these devices.

First, my plan is to run ROP and I have looked at the procedure in the instruction book a number of times now. I haven't actually had the chance to try it out yet but I plan to run it this weekend. Now, keep in mind that my knowledge on this subject is limited so my question may appear stupid. What values should I be looking at for my EGT/CHT if the engine is leaned out to a safe level? What is the absolute maximum EGT/CHT I should see by the time i'm finishing turning the mixture knob? Also, without getting into a long discussion on this topic, do any of you with a carbureted engine run LOP?

Second, my fuel flow is indicating properly at about 17.5 during T/O once the value is settled. The book recommends that several flights be flows while noting the amount of fuel used per the JPI and the actual amount used to refine the "K factor". Is this worth the effort?

Finally, for a 63c, can someone verify that total USABLE fuel capacity is 48gal with a tank capacity of 52gal? I ask because the POH does not explicitly state this info.

 

 

I'm sure others will chime in on your questions, but here is what I can offer. The EGT temp max is pretty high. If the probes are placed where the manual recommends, I would expect them to be in the 1,300°+ range. At peak EGT, I think I have seen something close to 1,400°.

The peak CHT will be different than my fuel injected version. The C owners with and without a doghouse will have a better idea than me. My CHT in the summer is around 330° and in the winter in the 290° range with it leaned 80° rich of peak.

I can usually get my fuel usage within a gallon when in the 25+ gallon used range. Most of the time it is 3% or less off. It will vary between fill ups. I think the temp of the fuel when I filled versus when I fly has something to do with it. Sort of like when they fill your propane tank and they calculate the volume based on a temperature (60° on my bills).

As for quantity levels, my bladder tank plane should be able to hold 54.7 usable. When my mechanic installed my 900, he needed to calculate out the exact amount of fuel the tanks could hold. When he measured it, he did it twice because it was much lower than it was supposed to be. He found he could only put 50.5 gallons in. I will be calling O&N before my annual to see if they have any thoughts on why I lost 4.2 gallons of usable. Hopefully your bladder less plane will be more consistent with the POH.

Sent from my iPad using Tapatalk

[carusoam]

Notes on using a JPI to display leaning data....

1) there are two modes.  These can be accessed through a menu feature.  Get the user guide online for proper buttonology on how to set LF mode (Lean find).

2) for ROP, Select the ROP mode.  For LOP select the LOP mode.  As you lean the mixture, the JPI will keep track of where the peaks occur and let you know the next step as you go lean or ROP by your selected value in °F.

3) I believe the difference of the two modes is ROP tracks the first cylinder to peak.  Then enrich °ROP from that first peak.

4) LOP mode tracks the last cylinder to peak.  As you lean past the last peak, you set the mixture °LOP from there...

5) the raw EGTs are know to add little value.  They are effected by many variables including their location in the exhaust pipe.  Closer to the valve, hotter they get by far.  Further down the pipe exhaust gasses cool as they expand....

6) Important values are FF at first peak and FF at last peak.  The FF difference is your GAMI spread.  Really balanced fuel injectors peak very close together.

7) speed of mixture changes takes some getting used to.  Some EGT sensors are thin walled and react quickly.  Some are thick walled and their response time is enormous.  Quick test: change the mixture a small amount, wait to see how long the data takes to settle at the next level.

8) going from full rich to near peak happens quickly when you know what you are doing.  The first few times takes a lot longer to know where peak is to sneak up to it.  Sneaking up to it or through it gives good data.  Rushing through it, the sensors are still reaching peak, but the mixture has been changed too quickly for the sensors to know when peak actually happened.

9) levels of safety are available to protect your engine.  The bad part of the mixture curve is called the red box.  The safe place to operate is outside the red box.  For Normally Aspirated engines the red box is limited to altitudes of 8,000' and above.  This is natures way of limiting available HP because there isn't enough MP to exceed 65% hp.

10) the POH probably gives brief instructions on how to lean for best power and best economy.  Best power is often 50°ROP and is a known too hot spot to operate.

11) For my IO550 there are a few settings that I have (nearly memorized)...

Climbing is done by a deep ROP mixture setting 200 to 300°F, adjusting mixture as it naturally gets richer every 1000’ or so...the ship's EGT gauge has a blue box on it.  Keep the EGT in that range while climbing.  When the needle falls out the bottom, adjust the mixture.  If you don't have a blue box, use a post-it note to aid your memory.  The G1000 uses a white box on the screen.

Max cruise speed is a generous 100°F ROP...175 knots is pretty fun at 15gph.

Lean cruise depends on how well balanced your FIs are and how well balance the air intake tubes are.  At lower altitudes the IO550 can run 90-100°F LOP.  Pretty efficient flying occurs there.  The speed penalty for going that LOP brings you back to J speeds.  No self respecting O driver is going to fly with max efficiency to achieve J speeds.  (Just having fun, j speeds are pretty good!)

Realistic cruise efficiency occurs just past peak.  All the fuel is being burned with a slight amount of excess air available...  Maximum power is being generated for the MP that is available.

12) equipment that is required...  EGT and CHT for all cylinders.  FF meter for real ease of use data collection.  So many Cs left the factory without this level of hardware it has taken a long time to get the community up to the level of sharing this valuable experience.

13) users manual for the JPI....  Know how to set the LF mode to ROP or LOP.

14) Best efficiency occurs with the throttle plate wide open.  This is why leaning experiments and practice are usually done at high altitudes during a trip. Instead of doing it at lower altitudes with a partial throttle setting.

15) At first, collect some data, take it home and review it. The graphs should show all four cylinders behaving the same or very similarly.  If they are not, Leaning experiments are not recommended.  Any questions, post JPI graphs on MS to get help interpreting them.

16) collect the whole flight data.  See where start-up occurs, leaning for taxi shows up next, the run-up is often very interesting as is the climb and cruise portion.

17) CHT data is good for maintaining the health of the cylinders.

18) when you get really experienced at using these tools you will know FF numbers that work really well for each section of flight. They will vary with altitude and weather so they are not a substitute. But they do get you pretty close.

19) Some engine monitors are really good and have extra functions combining the FF @ peak data with CHTs on the display. 

20) We have one engineer pilot that has reported the ability to get an LOP setting in his carbureted M20C.  The challenge of having a carburator becomes more obvious twitch the higher level of data available.  There isn't an adjustable fuel nozzle for each cylinder.  There is one main nozzle and a secondary nozzle that is open at FT. 

For efficiency, cut the secondary nozzle by not running WOT.  

To improve the spray mixture, close the throttle plate some more to increase turbulence in the carb, spreading fuel droplets around is good.

To improve the evaporation of the mixture, add a touch of carb heat. Evaporating the fuel allows mixing at the molecular level where it is important.

Having a carb temp gauge is helpful for this.

When you have an MP setting that works, a mixture setting that works, and a carb temp that works write it down and share it here on MS.

21) Not all engines are amenable to LOP OPs.  What other planes have difficulty with running LOP?  The Bravo doesn't have a very user friendly LOP range.  It can be run LOP, but the power level where it runs smoothly isn't at a very comfortable Bravo speed.  It has tunable fuel injectors, but it doesn't have tuned air intake pipes.  Air flow in a reciprocating engine is pretty complex due to intake valves opening and closing and air being a compressible medium...

22) Dog house Cs have very high CHTs, 400s.  Valve type is reported to be part of the CHT issue. Parallel vs angle.  Engine timing is often a cause of higher CHTs.  What is the mag timing set for on a C?

23) No matter what the books say for usable fuel, to depend on the number, it is best to start with them empty and fill them up.  Measure the difference.  One at a time of course.  The fuel pick up does not have a well to sit in.  A few gallons can be in there but not available to get out.

Let me know if I missed something.  It got late while I was typing... I am only a PP.

Best regards,

-a-

[markazzarito]

3 hours ago, par said:

So we have been able to troubleshoot and correct the issues. It took a call to help center to get all the values put in but things now seem to be working correctly. However, I do have a couple of questions for you guys who have been flying with these devices.

First, my plan is to run ROP and I have looked at the procedure in the instruction book a number of times now. I haven't actually had the chance to try it out yet but I plan to run it this weekend. Now, keep in mind that my knowledge on this subject is limited so my question may appear stupid. What values should I be looking at for my EGT/CHT if the engine is leaned out to a safe level? What is the absolute maximum EGT/CHT I should see by the time i'm finishing turning the mixture knob? Also, without getting into a long discussion on this topic, do any of you with a carbureted engine run LOP?

Second, my fuel flow is indicating properly at about 17.5 during T/O once the value is settled. The book recommends that several flights be flows while noting the amount of fuel used per the JPI and the actual amount used to refine the "K factor". Is this worth the effort?

Finally, for a 63c, can someone verify that total USABLE fuel capacity is 48gal with a tank capacity of 52gal? I ask because the POH does not explicitly state this info.

 

I have a 63c with an EDM 700

1) EGT CHT display values will be largely dependent on the atmospheric conditions trust the unit then listen to the engine to verify when leaning. You can usually expect CHT at cruise between 340 and 380 EGT value on leanest cylinder when leaned to 50 ROP will be between 1350 and 1500. Per JPi manual LOP is not reccomended for carbureted engines.

 

2) I found my fuel flow to be very accurate and did not need to adjust k factor. To test this fill your tanks fly note the total fuel flow than top your tanks off the amounts should be very close to equal.

3) Your tanks are 24 gallons per side in a 63C.