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IOX-370 Titan engine Propblems

planenuts

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I have the Titan IO-370 engine installed in my PA-18 clone experimental. The engine was run at the factory for 3 hours and I have flown it for 5 hours. No problems except high CHTs on number 3 and 4 cylinders. (400-420) Baffling corrections are helping with that. The engine has a Slick mag on the left, and an Emag on the right, with the jumper cable in to give the A curve. After last flight, I did some more rigging for a heavy left wing, and some other adjustments, and attempted to fly it again. The engine when started was missing and shaking very badly. It would idle, and then on its own, increase in RPMs up to about 1,100 rpms. Pulling the mixture to almost shut off would get it to idle a little bit lower. When mixture is moved to shut off no increase in RPMs. I then checked both mags, did a baby bottle flow test on the injectors, check all plugs and leads, tightened up the air intake tubes and no better. Sent the Performance Aero injector back to have it factory checked, they did and found no problems. Great customer service from them. No charge.
Tried engine again, no change. Number 4 cylinder is running much cooler than the others. I have had the local A&P, IA go over it, and he can not understand it, brought in a seasoned Lycoming Engine guy, and he is stumped. We did bore scope the cylinders, and found no problems. We have about covered every thing, and still no relief. It does the same on either mag and both mags. Fuel pressure is about 28 to 30 lbs, and flow was about 10 gal an hour when it was running correctly. Hoping some of you guys can help me with new ideas. The tech at Performance Aero guessed it would be an intake leak, but we have gone over those and changed gaskets. Have a set of SDS intake flanges with the o ring grove in it on order.
Stumped
Thanks
Bruce
 
Does your high pressure fuel pump change how it runs? Have you checked the diaphragm pump’s safety tube for fuel?

Forward facing servo? Do you have a sniffel valve installed?
 
Does your high pressure fuel pump change how it runs? Have you checked the diaphragm pump’s safety tube for fuel?

Forward facing servo? Do you have a sniffel valve installed?

The high pressure fuel pump does not change it any, on or off. The unit is a vertical mount with no sniffel valve installed. I have seen no evidence of fuel from the safety tube of the mechanical pump.
Thanks
 
It sounds like it was flooded. Did you try to run it up to higher RPMs to clear it? Inconsistent fuel flow initially after hot starts is a common thing. So is excessively rich idle fuel supply. Look for black exhaust smoke at idle.

Who is Performance Aero? Do you mean Airflow Performance? In any case here’s an excerpt from API’s purge valve manual I posted on the other IO-370 thread. Whether a purge valve is recommended or not depends on which servo is used. Or so I was told. One work-around is to shut the fuel valve off while taxiing to parking to reduce fuel and subsequently fuel pressure in the system after shutting down. I was advised to get in the habit of turning fuel off for parking.

Modern light aircraft fuel injection systems are of the low pressure constant flow type. Fuel is metered and is delivered to air bled nozzles which atomize and spray the fuel at each intake valve. Airflow Performance and Bendix fuel injection systems meter fuel to the engine based on engine air consumption. The fuel regulator in both these types of injection systems do not return any fuel to the tank, therefore only the fuel that is used by the engine flows through the fuel controller. Vapor in these types of metering systems causes the fuel regulator to operate erratically and poor engine performance will result. This is usually evident during hot restarts. Hot restart problems are a typical complaint of pilots operating fuel injected engines. After engine shut down heat in the cowling and engine tends to boil the fuel in the fuel control, fuel pump and related fuel metering components. Some of the fuel expands in the nozzle lines and gets forced through the injection nozzles and into the engine. This leaves hot fuel and fuel vapor through out the complete fuel metering system, engine driven fuel pump included. During an attempted start under this condition usually results in the engine starting for a moment then quitting. The pilot is then faced with decision of how to proceed with the start procedure. Flooding the engine then cranking the engine until it starts is usually done. This procedure is dependent upon battery life which sometimes expires before the engine starts. Engines which use the high pressure diaphragm fuel pump, experience another problem which influences the ease of restarting the engine. By their design the diaphragm fuel pump acts like an accumulator when the engine is shut down. This keeps fuel pressure on the fuel controller, and leakage in the idle cut off circuit of the fuel controller will allow the fuel to bleed off into the engine. This can cause run on in idle cut off and flooding of the engine initially after shut down. All Airflow Performance, Inc. fuel injection systems come with the purge valve as standard equipment typically installed as an assembly on the flow divider or purge valve. In addition to the above operational issues with this type of injection system, Airflow Performance fuel controls incorporate a rotary mixture control valve. Due to the inherent design of the rotary valve the device does not give zero leakage at ICO. Therefore even though the engine may shut down using the mixture control the purge valve will give a clean ICO under all circumstances.
 
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Thanks Stewart, I get the same reaction with hot or cold start. I did try running it up to 1600 rpms and the engine shook so violently that it was a concern. I certainly will try that again, thanks for your response
Bruce
 
Doesn’t make much sense. Simple enough to check Emag timing. Make sure your local guys didn’t time in advanced like the Slick on the other side. Good luck.
 
These are indications of a mixture being too lean.
The engine when started was missing and shaking very badly. It would idle, and then on its own, increase in RPMs up to about 1,100 rpms. Pulling the mixture to almost shut off would get it to idle a little bit lower. When mixture is moved to shut off no increase in RPMs.
Since you are flying it ... does it run smoother at higher rpms? How smooth?

Do you have the Airflow nozzles installed? https://airflowperformance.com/wp-content/uploads/2016/11/INJECTOR-NOZZLES.pdf
IF yes ... and it runs smooth enough to fly it (I assume you have an all cylinder CHT/EGT instrument installed?) perform the tests as described in this manual:
https://airflowperformance.com/wp-content/uploads/2015/12/Nozzle-Tuning-Instructions.pdf

You may find the nozzles on #3 & #4 are too lean (small).

This:
When mixture is moved to shut off no increase in RPMs.
is an indication that the idle mixture is set too lean. A simple adjustment, fix that first.

IF you are using the standard Lycoming nozzles, send them to Airflow to have them modify them to their version as described above. It then becomes very easy to fine tune the mixtures between the cylinders. Not expensive.
 
I had been flying it until this started, but not since. The emag is set to T/C, I have checked that twice. I have the Performance Aero nozzles and next plan was to switch the nozzles to see if the cool cylinder followed the nozzle. I will try to adjust the idle mixture and see if anything happens. When I sent the unit back to Performance Aero they set the mixture and idle speed according to mid range based on their experience.
Thanks guys for the input, will be back at the hanger tomorrow and give it another try.
Thanks
Bruce
 
Have you carefully checked that the spark plug wires are connected to the correct plugs? Were they changed since the engine was test run at the factory?
 
When I sent the unit back to Performance Aero they set the mixture and idle speed according to mid range based on their experience
That is just to give you a starting point. The final idle mixture adjustment is up to you and is specific for your engine.

What procedure are you using to set your idle mixture?
 
The change from running well to not running well happened quickly. If nothing was adjusted at the engine then something failed. If anything was adjusted at the engine that’s where to look, but Bruce sounds like a smart guy and he knows that. Induction leak sources would be flanges/gaskets at the cylinders, not likely to fail instantly and easy to inspect. I presume the 370 uses O rings to seal tubes at the sump. If one of those failed it would be hard to diagnose without pulling tubes to check. Here’s a pic if you aren’t familiar. I don’t know squat about flow dividers and how they fail but I know they do. I’d think the FI provider would have considered that.

Re: timing? Make sure you’re using the correct timing marks. They’re different on the front and back of the ring gear support. The only reason I bring that up is that I’ve had that brain fart myself and timed with the prop side TC mark to the case seam. Caught myself before I started it but humans do what humans do, and that’s to err.

You said you flow tested the injectors. Did you index them when you reinstalled?

Aviation’s more fun when stuff works. Keep the faith!
 

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That is just to give you a starting point. The final idle mixture adjustment is up to you and is specific for your engine.

What procedure are you using to set your idle mixture?

I have adjusted it a lot before I sent it off not since. The way I have always set the idle mixture adjustment is to get a 20 to 35 RPM rise when mixture is pulled full lean. It is not doing that now, it just stops. As you mentioned sounds like the idle is too lean. I will start to adjust it again to see if any relief. It did not before I sent it off, gave me the thought that it was something wrong in the injector its self.

I will be trying this tomorrow, Monday and see what we get.

Thanks
 
The change from running well to not running well happened quickly. If nothing was adjusted at the engine then something failed. If anything was adjusted at the engine that’s where to look, but Bruce sounds like a smart guy and he knows that. Induction leak sources would be flanges/gaskets at the cylinders, not likely to fail instantly and easy to inspect. I presume the 370 uses O rings to seal tubes at the sump. If one of those failed it would be hard to diagnose without pulling tubes to check. Here’s a pic if you aren’t familiar. I don’t know squat about flow dividers and how they fail but I know they do. I’d think the FI provider would have considered that.

Re: timing? Make sure you’re using the correct timing marks. They’re different on the front and back of the ring gear support. The only reason I bring that up is that I’ve had that brain fart myself and timed with the prop side TC mark to the case seam. Caught myself before I started it but humans do what humans do, and that’s to err.

You said you flow tested the injectors. Did you index them when you reinstalled?

Aviation’s more fun when stuff works. Keep the faith!

I put the injectors back in the same place they were removed from. The engine has an aluminum sump, and I am not familiar with the seal that was use. Youtube university has a video on putting pressure in the cylinder, with it in compression mode, and then turn the engine backward to open the intake valve, and let it burp the compressed air down through the intake while some one sprays the out side of the intake tubes with soapy water. In car engines we spray brake cleaner on the intake manifold to see if the rpms jump up, meaning the fluid was sucked in through the intake and was ignited. Not sure I want to try that with the prop turning over. Will see. I am using the timing marks on the rear face of the ring gear, matched to the center of the case. I checked to see if the marks lined up with top dead center and they do.
Your right, when it works, it is great. I think of how many times a day I start my car, and am amazed as its so easy.
Thanks for the great input.
Bruce
 
Quick note, I have been referring to the fuel unit as Performance Aeromotive, when it is actually Precision Airmotive, it is the experimental Silver Hawk unit. Sorry, but this must be getting to me.
Bruce
 
I have adjusted it a lot before I sent it off not since. The way I have always set the idle mixture adjustment is to get a 20 to 35 RPM rise when mixture is pulled full lean. It is not doing that now, it just stops. As you mentioned sounds like the idle is too lean. I will start to adjust it again to see if any relief. It did not before I sent it off, gave me the thought that it was something wrong in the injector its self.

I will be trying this tomorrow, Monday and see what we get.

Thanks
You don't mention the rpm you start with when you get your 20 to 35 RPM rise. You should set the rpm at just a little over 1000 rpm. Pull the mixture to cut off, then notice a 10-20 rpm rise. If no rise turn the setting towards rich. If a high number of rise turn it towards lean.
 
Have you inspected all the injectors? Wonder if partial clog or intermittent would cause such behavior. Is the fuel flow at full throttle as specified? Excessively high fuel flow could mean a partially clogged injector. Had piece of trash that floated around wreaking havoc. Finally found it in number 3.
Check all the linkages for security and play.
look for something simple. It usually is.
 
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Probably not your problem since you are fuel injected, but a common issue on carbureted planes is the primer plunger not being locked after use and causing a very rich condition. Small thing that causes lots of head scratching.
 
Have you inspected all the injectors? Wonder if partial clog or intermittent would cause such behavior. Is the fuel flow at full throttle as specified? Excessively high fuel flow could mean a partially clogged injector. Had piece of trash that floated around wreaking havoc. Finally found it in number 3.
Check all the linkages for security and play.
look for something simple. It usually is.

Thanks, put the injectors in cleaner over the week end. Hoping to start the engine yesterday, but a down pour of rain all day. Try again on Wed. I see how a floating piece of trash could be hard to find.
Bruce
 
You mentioned "checked plugs and leads", but definitively? I recently had a bad plug that "checked" ok, and was ok at runup power (1800), but missed consistently at flight power (2450). Combination of EGT and in-flight mag check identified the culprit.
 
You mentioned "checked plugs and leads", but definitively? I recently had a bad plug that "checked" ok, and was ok at runup power (1800), but missed consistently at flight power (2450). Combination of EGT and in-flight mag check identified the culprit.

Good point. I just had an automotive plug break off in my hand when I gently removed a plug wire. No impact or abuse. Stuff happens.
 
Yesterday, after exhausting every possible thing that could be wrong with this engine, we found the problem by back tracking to what i had done on the engine between running great, and terrible. I had increased the idle mixture, to get more rise out of it when pulling mixture control, and lowered the idle speed just a touch, from like 1000 to 800 RPMs. That was all I could remember doing to the engine. Ran it yesterday, and it still was running very rough as before, and shaking the plane. A bystander who had not been thorough all of this with me was looking at it running not particularly looking at the engine as all of us had been doing, and announced that the prop seemed way out of balance. What the heck, could not be. Well as suggested above, it is the simplest things usually, and sure enough I had forgotten that I also pulled a little pitch out of the Whirlwind prop, ground adjustable, before this started. I am terribly embarrassed to say one blade was pitched to 16 degrees, the other was a negative 16 degrees. I have no idea how I could have done something like that, but I am the only one that touches the plane until I brought in some experts to help with the latest problem. We were all concentrating so hard on the engine none of us noticed the prop pitch. Needless to say, I have wasted a month chancing my my tail, only to find it was something done so poorly by me. Can't blame this on anyone else. Thanks to you guys for all the help, no doubt the engine is running the best ever after all the work we have done trying to solve this mystery. I still don't know how I did that, maybe you should not drink a beer while working on your plane. Only excuse I can come up with.
Bruce
 
Sounds like the two guys on each end of a two handed hand saw, go to me, come from me. Those prop blades could not make up their mind which way to go!
Glad it was simple fix.
 
Yesterday, after exhausting every possible thing that could be wrong with this engine, we found the problem by back tracking to what i had done on the engine between running great, and terrible. I had increased the idle mixture, to get more rise out of it when pulling mixture control, and lowered the idle speed just a touch, from like 1000 to 800 RPMs. That was all I could remember doing to the engine. Ran it yesterday, and it still was running very rough as before, and shaking the plane. A bystander who had not been thorough all of this with me was looking at it running not particularly looking at the engine as all of us had been doing, and announced that the prop seemed way out of balance. What the heck, could not be. Well as suggested above, it is the simplest things usually, and sure enough I had forgotten that I also pulled a little pitch out of the Whirlwind prop, ground adjustable, before this started. I am terribly embarrassed to say one blade was pitched to 16 degrees, the other was a negative 16 degrees. I have no idea how I could have done something like that, but I am the only one that touches the plane until I brought in some experts to help with the latest problem. We were all concentrating so hard on the engine none of us noticed the prop pitch. Needless to say, I have wasted a month chancing my my tail, only to find it was something done so poorly by me. Can't blame this on anyone else. Thanks to you guys for all the help, no doubt the engine is running the best ever after all the work we have done trying to solve this mystery. I still don't know how I did that, maybe you should not drink a beer while working on your plane. Only excuse I can come up with.
Bruce

This happens a lot. Your the only one to fess up. You've heard of PIO (pilot induced ossilation) this is PIV

Glenn
 
Don’t feel to bad, I reinstalled my ground adjustable prop the other day, pushed cub out, fired it up and it didn’t want to move. So I increased the throttle, still nothing, went to full throttle and it started to back up. Oops, got the prop pins on the wrong side of the adjust pin. Loosened the hub and corrected my muss up and went flying. Life is full of challenges!
 
Don’t feel to bad, I reinstalled my ground adjustable prop the other day, pushed cub out, fired it up and it didn’t want to move. So I increased the throttle, still nothing, went to full throttle and it started to back up. Oops, got the prop pins on the wrong side of the adjust pin. Loosened the hub and corrected my muss up and went flying. Life is full of challenges!
I did the same thing on the first install.
 
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