I'm having issues with my new RV 7 engine. The fresh majored 0-360 runs very rough. It will not develop full power, either. So far I've confirmed that the dual pmags are firing and timed correctly. Compression is good. At run up, all cyl head and EGT temps rise and fall together, evenly, so I believe all jugs are firing. But the engine is very rough. I'm now investigating the Ellison throttle body installation, as I'm out of other places to go. Any other thoughts? This is a new install on my newly finished 7, fresh gas, new plugs all fire well, fresh gas, etc... Any thoughts?
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O360 problem
- Thread starter Jimzim
- Start date
N941WR
Legacy Member
As always, check the easy stuff first.
Make sure all the plug wires are pushed all the way on to the sparkplugs and into the P-mags. They should "click" as they are pressed on.
Make sure your auto plugs are not the type with the screw on caps, like what they used to have on lawnmowers. NGK makes two version of the BR8ES, and you want to use the ones with the solid caps.
Check your plug wires to make sure they are not resting against/touching the engine mount or engine case anywhere. They can short out through the wires and cause an engine stumble.
After that, look at the fueling. The Ellison can be very difficult to setup correctly.
Make sure all the plug wires are pushed all the way on to the sparkplugs and into the P-mags. They should "click" as they are pressed on.
Make sure your auto plugs are not the type with the screw on caps, like what they used to have on lawnmowers. NGK makes two version of the BR8ES, and you want to use the ones with the solid caps.
Check your plug wires to make sure they are not resting against/touching the engine mount or engine case anywhere. They can short out through the wires and cause an engine stumble.
After that, look at the fueling. The Ellison can be very difficult to setup correctly.
Check the intake
Several of the threads I read concerning the TBI, before settling on the Bendix injection system, mentioned intake airflow issues. Primarily the mixture went lean with forward flight. Nevertheless, I would look at your intake ducting to ensure that there are no issues there. Some have resorted to "air straighteners" to clean up airflow entering the TBI.
Several of the threads I read concerning the TBI, before settling on the Bendix injection system, mentioned intake airflow issues. Primarily the mixture went lean with forward flight. Nevertheless, I would look at your intake ducting to ensure that there are no issues there. Some have resorted to "air straighteners" to clean up airflow entering the TBI.
Mentioning whether the engine was run in a test cell after overhaul will help rule out some other possibility's.
Thanks for the tips, I'll investigate each. The plug wires are well routed with stand-offs and such, so I don't think that or plugs are the problem. Also, the temps are even between cylinders, which indicates they are all firing evenly. The thing is, the roughness isn't subtle! At 850 rpm, it wants to just about come out of the mount!. Smoother at higher RPM, but never very smooth at all, and never will develop full power or full static RPM. The prop is a new sensenich and I can't imagine it could be that far out. To shake like this I think 2 inches would have to be missing off one tip! Anyway, the condition continues regardless of whether I'm on left, right, or both pmags, so spark seems ruled out. Therefore I suspect fuel distribution is the culprit, but again, it really shakes! Yesterday I sent the TBI to Ellison for a rebuild and will try it when it returns. As far as airflow into it, I removed the filter and duct and ran the engine straight with no change in the results so intake turbulence doesn't seem to matter. I'm just running out of ideas if the TBI overhaul doesn't do it... After 6 years of build, I really want to fly!!!
N941WR
Legacy Member
Did you time the P-mags correctly? Meaning, was the engine at TDC when you blew in the tube and not at 25* BTDC? (Common mistake for people who are used to timing traditional mags.)
Make sure to put the jumper in to force the P-mags to the lower curve.
If you have a FP prop, pull it off, slide it on a shovel handle supported between two saw horses to see if it is balanced.
Make sure to put the jumper in to force the P-mags to the lower curve.
If you have a FP prop, pull it off, slide it on a shovel handle supported between two saw horses to see if it is balanced.
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Yes, I verified the timing of both Pmags and also did the pull through test. All plugs firing and at the correct time. I'm using TDC, not 25 degrees...and spoke with Brad. As he points out, if the roughness is the same on either mag or both mags, it's likely not mag related. The strange thing is that the CHT's and EGT's on all 4 cylinders behave perfectly normal. So all 4 are firng and runnning and producing power, but a really rough condition persists. By rough, I mean that the engine visibly shakes in the mount, and yes, I checked the donuts, mounting bolts, etc... and the mount itself is right out of th box from Van's... I keep coming back to uneven fuel distribution or huge variation in mixture to the cylinders??? Leaning helps some but not nearly enough to smooth hings out to normal. My Cessna 140 prop was out of balance and it felt a bit rough, but nothing like this! Thanks for the tips, I'll keep after it. Any other thoughts appreciated!
Ralph Inkster
Well Known Member
I assume this is a new Ellison installation. Have you gone thru the full Ellison mixture & idle adjustment process for the throttle body? They state the factory settings are enough to get the engine running but then describe an extensive list of adjustments to get it running well.
If the engine had test cell run time after the rebuild, the rebuild shop probably used their own test induction (off the shelf shop carb or injection system), but later removed and shipped your engine with a new in the box Ellison TB un-adjusted. You may be lucky to get a unit straight out of the box that runs well at your particular altitude & humidity, or more likely a unit needing a lot of adjusting that initially runs like a total dog.
If the engine had test cell run time after the rebuild, the rebuild shop probably used their own test induction (off the shelf shop carb or injection system), but later removed and shipped your engine with a new in the box Ellison TB un-adjusted. You may be lucky to get a unit straight out of the box that runs well at your particular altitude & humidity, or more likely a unit needing a lot of adjusting that initially runs like a total dog.
The engine was not run on a test stand after overhaul. I wish it had been, as I'd feel better about it. Also, I failed to mention that the Ellison is used. When I get it back from the factory, I intend to go through the full set up procedure. I tried to do that earlier, but didn't have any luck. We'll see what happens this time around. Thanks for the suggestion.
Jim (2015 paid)
Jim (2015 paid)
Danny King
Well Known Member
Rough 0360
Check for air leaks, and idle mixture.
If the engine is an angle valve, check the O-rings on each intake tube at the sump. They can roll or get cut during tube installation and suck air causing a rough idle. Check the intake tube flange gaskets at each cylinder and that the flange is evenly tightened.
If parellel valve, check hose and clamps between intake tubes and sump, and also at the cylinder flanges.
Check idle mixture on throttle body. Lean mixtures due to air leaks or lean idle mixture will cause a rough and weak idle.
Check for air leaks, and idle mixture.
If the engine is an angle valve, check the O-rings on each intake tube at the sump. They can roll or get cut during tube installation and suck air causing a rough idle. Check the intake tube flange gaskets at each cylinder and that the flange is evenly tightened.
If parellel valve, check hose and clamps between intake tubes and sump, and also at the cylinder flanges.
Check idle mixture on throttle body. Lean mixtures due to air leaks or lean idle mixture will cause a rough and weak idle.
If you had a huge variation in mixture your egts would not be equal.
Prop balance is very important. You say it feels like there are inches missing off a blade, but in reality an inch off a blade would make the engine part company from the airplane, it might not be your issue but at least do a static balance of the prop. Easy and cheap to do. I would not run a prop with at least checking static balance.
Prop balance is very important. You say it feels like there are inches missing off a blade, but in reality an inch off a blade would make the engine part company from the airplane, it might not be your issue but at least do a static balance of the prop. Easy and cheap to do. I would not run a prop with at least checking static balance.
Leak down test
Time for a leak down test. Or at least give it a pull thru and see if you get a squeeze on each cylinder. It's possible the valve lash was not set correctly and you have a valve being held open.
Also, good advice to look at the intake system for leaks. If it runs good at WOT then thats a good sign you have an intake leak.
Good luck
Tim
Time for a leak down test. Or at least give it a pull thru and see if you get a squeeze on each cylinder. It's possible the valve lash was not set correctly and you have a valve being held open.
Also, good advice to look at the intake system for leaks. If it runs good at WOT then thats a good sign you have an intake leak.
Good luck
Tim
Jim,
I flew an Ellison for 10 years on my O-320 powered -4 and am a big fan of these TBIs.
From what you describe, I think it is set too lean, the adjustment is critical to get the best operation.
I recommend you go back through the adjustment procedure and follow it to the letter.
I believe after doing so your engine will run smoothly and develop full power.
I had a similar problem with mine in the beginning and once adjusted properly I never had to touch it again.
Good Luck,
Glenn
I flew an Ellison for 10 years on my O-320 powered -4 and am a big fan of these TBIs.
From what you describe, I think it is set too lean, the adjustment is critical to get the best operation.
I recommend you go back through the adjustment procedure and follow it to the letter.
I believe after doing so your engine will run smoothly and develop full power.
I had a similar problem with mine in the beginning and once adjusted properly I never had to touch it again.
Good Luck,
Glenn
I did look for induction leaks, and everything appears new and tight. As for the prop, I'll look at a static balance check. By the way, it's a parallel 0-360. I have high hopes for getting the TBI back rebuilt and then dialing it in. I know others who have had great success with Ellisons and that's how I ended up with it. Once they get going, I'm told they are really great! Any other tips appreciated and I'll report on results as I move forward...
Thanks, Jim
Thanks, Jim
So the throttle body came back from Ellison totally rebuilt. Installed it and ran the engine again, absolutely no change. Engine still rough and shakes the engine mount at lower RPM. We began looking at the valve train and may be seeing an issue. There are gaps between some of the rocker arms and valve stems that look to exceed spec for an engine that has been ran; i.e. the lifters have been pumped up with oil. It is as if the pushrods are too short. We are looking deeper into this scenario, as that would mean the valves are not opening fully... We'll see where this leads.
Jim
Jim
