R

rv10ch

I'm New Here
I always thought that fuel injected engines had a difficult warm start behavior, but on my engine that is child's play compared to the cold start behavior. So I suspect I have some kind of an engine problem but I don't know what an I need some help.

I've got a rebuilt Barrett IO-540 with AFP fuel injection, 9:1 pistons, left Bendix magneto and right Electroair electronic ignition. I've studied and used AFP's recommended start procedure. It will not ignite. After a while (about three times ten seconds) I normally get anxious that I have flooded the engine and do an "flooded engine start" with full throttle. In this mode I've managed to get it started every time.

When it is finally started, the warm up RPM is not stable (at 1200 rpm and below). At mag check RPM (1800) it is fairly stable and in flight i notice no issues. The unstable RPM may be worse when returning from a flight when the engine is hot.

The RPM is unstable on both ignitions alone as well as both together. So it seems not to be related to ignition problems.

After start (cold engine) I see a fuel flow of about 6 gph and a fuel pressure of 20 psi (at 1000 rpm). Is that OK?

Also worth mentioning is that I have not installed the AFP purge valve, or to be precise, it is installed but plugged and inoperable - and leak free.

Any advise what to check for is greatly appreciated.

Lorenz.
RV-10 #40280
 
engine

How much time on the engine? They tend to run a bit ragged the first few hours.
Has the idle mixture been properly adjusted?
I ALWAYS leaned immediately after start on the injected engines, whether an Aztec, Pitts or whatever.
A stable mid gage fuel flow reading for cold start is more reliable than timing. You just have to experiment and find what your engine likes.
What is the ambient temp. my experience is that all these engines run a little ragged at low r/m
. They are worse in hot weather and the straight exhaust is rougher than the crossover.
If none of this works check the induction tubes including removing the induction elbows-check for flatness and install new gaskets.
 
So,.. exactly what are you doing.... and what have you tried?

Have you tried less time on the booster before cranking? Changed any setting on the throttle or mixture?

I found I really needed less time on booster than recommended. (have a different system than you do)

p.s. might check the recommendations on the starter,... believe most recommend you not run them 10sec at a time
 
Rich?

In the airplane that I fly, I usually only see 2-3 GPH at 1000 RPM. This is a 300 hp Continental... but 6gph sounds high. Perhaps your to rich, which would cause rough idling and hard starting. That would explain why the flooded starting technique works for you.
-David
 
I've got a rebuilt Barrett IO-540 with AFP fuel injection said:
Lorenz,

I have the same Barrett engine with AFP injection and 9.0 pistons, with 2 Bendix Mags and purge valve. After 30 secs. purge, my cold start procedure is mixture full rich, throttle 1/2, fuel boost 5 secs. then ignition. Always starts within 2-3 blades and runs smooth immediately. In 2 years I have never had to do a flooded start. Hot starts are a non-issue with the purge valve. I recommend you hook it up; although it will not help your current issue. I will check my fuel flow & pressure at idle when I fly tomorrow.

I will leave it to the engine gurus to offer solutions, but will tell you that it is not normal/usual for this engine to run ragged/rough when new or cold.

Jim Berry
RV-10
Click to expand...
 
The RV-8 I fly requires no more than 1 second (yes, one second) of prime or it is too fat at start. My Hiperbipe needs the "logical" 3-5 seconds. Same injection system, but different boost pumps.

Forget the books and figure out what your system needs. If you are too fat, reduce the prime - if too lean... well, you know.
 
Cold start is a none issue

Jim Berry is right on.
My set up is the same as yours, although 8:1 compression.
Cold starts are a one revolution event and have been on this engine, 75hrs since new and 450 hours on the same set up in an RV8 IO-360.
There is no need to purge a cold engine and my throttle is barely cracked open so as not to exceed 1000 RPMs on start up. A few seconds of running and I lean the mixture to the max and the engine runs smooth as a sewing machine. I give it a few seconds (3to5) of boost (prime) for cold start.
I don't know the history of your plane or engine installation but the fact that your purge valve is not hooked up tells me someone was in a hurry to finish
the installation. This leads me to believe that certain final adjustments to the
idle mixture control and perhaps even magneto and electronic ignition timing adjustments have not been made.
Give us a little more info an someone will be able to pin point your starting problem. You can expect your set up to be absolutely trouble free when all adjustments are done correctly.
 
With ernst on this.

This is THE cold start procedure for an IO540

WOT, FULL RICH

Boost pump, on and as soon as the pressure gets to 20PSI or more count "One Thousand Two Thousand" and pump off.

Mixture ICO.

Throttle cracked enough to give you 1200 RPM.

Crank!


Hot start, Do nothing! Crack throttle the same, crank, as soon as it coughs, run the mixture up.

AFTER START - BOTH CASES

Lean until the RPM peaks, then ever so slightly starts to fall again. Taxi like this.

Runups done same setting at 1700 or so RPM, and richen ONLY enough to keep it smooth, no more. Watch EGT's all rise on each mag, if they dont, and one falls, you will know which plug! Cycle the prop ONCE!!

Return mixture to the leanest possible again before lining up.

Line up procedure....Pump on, Mixture rich......ROLL!

If your procedures are not like this, change! :)

This does EVERYTHING it should.....And NOTHING it shouldn't! ;)
 
Just to add my 2c -

I have found that with the idle mixture properly adjusted, on a properly operating FI system, that leaning at low RPM/taxi/run-up is not required.

I agree with leaning on the ground with a carb, that's a different animal.
 
Just something I found

When our IO540 would not start easily, hot or cold, we found we had a retard breaker magneto on the left (starting) side (no impulse coupling). It did not have a "shower of sparks" box hooked to it, therefore, not giving the necessary spark for easy starting. We hooked a Slickstart to it and the problem went away.
 
Here is how I have done it.

Apx 3-4 seconds of prime after the fuel pressure gauge hits 20#----with the mixture at full.

Crack throttle, crank----usually starts 2 or3 blades.

I always use the bypass valve to shut down the engine, never touch the mixture for shutting down.

Find out what works for you, and stay with it.
 
rv10ch said:
I always thought that fuel injected engines had a difficult warm start behavior, but on my engine that is child's play compared to the cold start behavior. So I suspect I have some kind of an engine problem but I don't know what an I need some help.

I've got a rebuilt Barrett IO-540 with AFP fuel injection, 9:1 pistons, left Bendix magneto and right Electroair electronic ignition. I've studied and used AFP's recommended start procedure. It will not ignite. After a while (about three times ten seconds) I normally get anxious that I have flooded the engine and do an "flooded engine start" with full throttle. In this mode I've managed to get it started every time.

When it is finally started, the warm up RPM is not stable (at 1200 rpm and below). At mag check RPM (1800) it is fairly stable and in flight i notice no issues. The unstable RPM may be worse when returning from a flight when the engine is hot.

The RPM is unstable on both ignitions alone as well as both together. So it seems not to be related to ignition problems.

After start (cold engine) I see a fuel flow of about 6 gph and a fuel pressure of 20 psi (at 1000 rpm). Is that OK?

Also worth mentioning is that I have not installed the AFP purge valve, or to be precise, it is installed but plugged and inoperable - and leak free.

Any advise what to check for is greatly appreciated.

Lorenz.
RV-10 #40280
Click to expand...

I have the same set-up as you do as far as the IO540, Left Mag and Right ElectroAir and AFP FI system. My purge valve is functioning though. I never have a cold start problem. I DO (contrary to what some say) purge the system for 10 seconds with boost pump on, mixture full rich and purge valve at ICO. After 10 seconds, open the throtle 1/4" and open the purge valve completely, count to 10 and crank.... fires up after 2 or 3 blades religiously. I do remember my fuel flow at idle reads only 2-2.5 GPH, not the 6 that you are experiencing. Hot starts are: Mixture full rich, purge valve at ICO, run boost pump 30-45 seconds to purge, then throttle at idle and crank simultaniously while slowly advancing the purge valve to open. Takes a second or two of cranking but the engine fires and idles fine. I would DEFINITELY hook up your purge valve and have your fuel flow meter checked. 6 GPH at idle sounds like an awful lot. If it is correct, maybe somehow you *are* flooding the engine? I am NOT an A&P, just giving you my experiencees with the same setup you have. Good luck!
 
FM200?

If you really have 6gpm flow at 1000rpm your idle mixture is way too rich and needs to be adjusted. If so, it is no wonder you have an erratic idle. Refer to the very nice instruction book from Airflow Performance on how to adjust. Using the mixture rather than the purge valve during start and shutdown will leak raw fuel into the throttle body causing a couple problems. Check with Don at Airflow and he will probably tell you those things first. He can also sell you an instruction manual.
 
Just to add my 2c -

I have found that with the idle mixture properly adjusted, on a properly operating FI system, that leaning at low RPM/taxi/run-up is not required.
Click to expand...

Walt, This would be a first. Something I do not quite agree with in your posts.

But Happy to learn something new. Please tell me more about the setup you believe is optimum. Of the ones I have seen, setup and tested as per the instructions, they all have been responding to ground leaning as I expected.

Not sure how much measrured effect it has on WOT/FR from the idle circuit. Never been interested to test it but it would be insignificant I would have thought.
 
Mattituck Engines website

To the thread starter, my own experience is most similar to RV 10 in Oz.

Check the tech advice section of Mattituck Engines website, then click on
"Good operating habits"

On the ground my mixture lever is about half way to ICO for peak rpm.

Best of luck!

PS I never purge, hot or cold. 2 slick mags,Slick Start on LH side. Air Flow Performace FI

I would guess you are flooding the pre start and running too rich after started. On the ground at idle you
can not hurt anything By leaning for peak RPM.
 
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RV10inOz said:
Walt, This would be a first. Something I do not quite agree with in your posts.

But Happy to learn something new. Please tell me more about the setup you believe is optimum. Of the ones I have seen, setup and tested as per the instructions, they all have been responding to ground leaning as I expected.

Not sure how much measrured effect it has on WOT/FR from the idle circuit. Never been interested to test it but it would be insignificant I would have thought.
Click to expand...

No scientific data, but having maintained a number of aircraft with both FI and carbs, I have noticed that lead deposits always seem heavier in carbed engines and I suspect this is mainly from ground ops. If the carb guys don't aggresively lean on the ground (and many do not) you can almost guarantee heavy lead deposits in the plugs.

Conversly most of the FI engines I see seem to run cleaner plugs overall and generally have less lead deposits even with no ground leaning (myself included).

You can adjust both for a 50 RPM increase, but in both cases the above still holds true.

I think the off idle mixture may be better controlled in the FI system and/or better atomization of the fuel may also be a factor.
 
:DAgreed, and the reason for better atomisation in the FI is most likely the air velocity and temperature of the engine early on, the cold one is not going to atomise as well with the carby.

I would suggest that following my tips in the previous posts will minimise lead balls, over 50 hours we get very few if any.

Like I say, does everything it should and nothing it shouldn't. One other benefit is that done the way I describe there is no chance whatsoever of anyone taking off partially leaned and in detonation. It drives me mad when I see folk lean just a little bit. One day they will forget and not realise it. Will clean up the pistons and heads nicely though!
 
I'll start with mixture adjustment

Thanks for all expressed wisdom here!

AFP's recommended procedure without purge valve is:

Mixture ICO
Throttle 1/8
Boost On
Move Mixture to full rich until FF 4-6gph and return to ICO
Boost off
Crank. When engine fires move Mixture to full rich and throttle to idle.

This is what I've tried - without success.

The high fuel flow is surely a sign that idle mixture is too rich. I had my difficulties to properly adjust mixture and idle rpm. The main problem was that an adjustment that was OK one day was off the next day. When Idle was adjusted to 750 rpm on day one it got below 600 rpm the next day. The same with the mixture. It was very sensitive to adjustments. When checking the mixture my DAR stated it was too lean, as there was no rpm rise when putting the mixture to ICO. I then adjusted the idle mixture by turning the rod one flat and that's I have been using.

RV10inOz: Your cold star procedure puzzles me: You crank with mixture ICO. When it fires, I suppose you run the mixture up as you describe in "hot start"?

So the first thing I will look at is idle mixture and see if aggressive leaning can make the engine smoother on ground.
 
I think we are homing in on the problem.
Your question to OZ tells me that you are cranking with the mixture full rich,
yet a few lines above you correctly describe the cold start procedure as stated by AFP.
4th line from the top
Move Mixture to full rich until FF 4-6gph and return to ICO
Click to expand...
You must have added a step by moving the mixture back to rich prior to cranking. This will most certainly flood your engine.
Your right hand will be on the power Knob (mixture:)) when the engine fires, advance the mixture knob.
You are correct, the adjustments to the idle mixture is very sensitive and unless you accomplish this task with an engine at operating temperature as described in the AFP manual you'll be chasing that sweet spot, where you get a 50 RPM rise on shut down forever.
As to leaning the mixture to the max with fuel injected engines I can't argue with Walt's real life experiences when looking at engines at overhaul time.
However, the 50 RPM rise you get on shut down is added richness you don't need for taxiing around and at today's fuel prices you might as well lean it to the max, you can't hurt the engine by leaning it on the ground.
While fouling the plugs is indeed a problem of less concern in injected engines, leaning to the max on the ground especially on the way back to the hangar will keep the plugs cleaner and ready for an easy start next time you go flying.
 
leaning

The first fuel injected Aztecs as well as the Twin Commanches fouled the spark plugs badly. I have always leaned the fuel injected Lycs on the ground.
 
N427EF said:
I think we are homing in on the problem.
Your question to OZ tells me that you are cranking with the mixture full rich,
yet a few lines above you correctly describe the cold start procedure as stated by AFP.
4th line from the top

You must have added a step by moving the mixture back to rich prior to cranking. This will most certainly flood your engine.
Your right hand will be on the power Knob (mixture:)) when the engine fires, advance the mixture knob.
You are correct, the adjustments to the idle mixture is very sensitive and unless you accomplish this task with an engine at operating temperature as described in the AFP manual you'll be chasing that sweet spot, where you get a 50 RPM rise on shut down forever.
As to leaning the mixture to the max with fuel injected engines I can't argue with Walt's real life experiences when looking at engines at overhaul time.
However, the 50 RPM rise you get on shut down is added richness you don't need for taxiing around and at today's fuel prices you might as well lean it to the max, you can't hurt the engine by leaning it on the ground.
While fouling the plugs is indeed a problem of less concern in injected engines, leaning to the max on the ground especially on the way back to the hangar will keep the plugs cleaner and ready for an easy start next time you go flying.
Click to expand...

Geeze my work here is done! :D

We are like a mutual admiration society :D:D :eek:

RV10CH I will send you a PM with contact details. Maybe we can talk one day. Although as Ernst will tell you.....it could take a few hours! :)

Cheers!

David Brown


PS the AFP procedure is fine, only slightly differenet to mine. Just worded different and a different measurement method. And if fuel flow for you is taking longer to get the value they talk about, try my method. You may be flooding things. I know I sound like a smart A$$ all the time but really, what I am telling you is the best way, does everything it should, and nothing it shouldn't! :)
 
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