1LikesTuning complication engine rich and lean at same time
02-04-2019, 02:56 PM
#1
Tuning complication engine rich and lean at same time
can’t seem to tune engine properly. Engine will start. Idle fine. But when it is reving up and or wide open throttle is held for more than 2 seconds the engine shows signs of being to lean. Engine carb was reset to a very rich setting. So rich that if idleing fuel will drop out exhaust and engine will need to clear the crank dramatalicly before moving. Once the excess fuel is cleared the lean signs show and cause heating issues as well as burnt glow plugs.
02-04-2019, 03:25 PM
#3
Air leak. It could be the carb, exhaust gaskets, pressure tubing, or tank.
Check the exhaust gaskets - engine to header and header to pipe. If the the problem continues I coat the O rings on both the high speed and low speed needle with a thin coating of wheel bearing grease to seal them and replace the pressure fuel tubing. If that doesn't correct it then it is probably engine bearings.
Lee
Check the exhaust gaskets - engine to header and header to pipe. If the the problem continues I coat the O rings on both the high speed and low speed needle with a thin coating of wheel bearing grease to seal them and replace the pressure fuel tubing. If that doesn't correct it then it is probably engine bearings.
Lee
02-04-2019, 06:03 PM
#4
Originally Posted by illmatic94
can’t seem to tune engine properly. Engine will start. Idle fine. But when it is reving up and or wide open throttle is held for more than 2 seconds the engine shows signs of being to lean. Engine carb was reset to a very rich setting. So rich that if idleing fuel will drop out exhaust and engine will need to clear the crank dramatalicly before moving. Once the excess fuel is cleared the lean signs show and cause heating issues as well as burnt glow plugs.
02-04-2019, 06:10 PM
#5
Originally Posted by Juice1
Sounds like you pretty much answered your own question... fat on bottom and too lean on top.
02-04-2019, 06:11 PM
#6
Originally Posted by Winner's Circle
Air leak. It could be the carb, exhaust gaskets, pressure tubing, or tank.
Check the exhaust gaskets - engine to header and header to pipe. If the the problem continues I coat the O rings on both the high speed and low speed needle with a thin coating of wheel bearing grease to seal them and replace the pressure fuel tubing. If that doesn't correct it then it is probably engine bearings.
Lee
Check the exhaust gaskets - engine to header and header to pipe. If the the problem continues I coat the O rings on both the high speed and low speed needle with a thin coating of wheel bearing grease to seal them and replace the pressure fuel tubing. If that doesn't correct it then it is probably engine bearings.
Lee
02-04-2019, 06:16 PM
#7
An engine cannot be rich and lean at the same time. It’s just not possible.
What engine is it?
How is the pinch? How much fuel has the engine seen (realistically)?
What fuel is being used? (Nitro/oil/fuel brand)?
Glow plug brand and heat range / plug #?
Has the fuel system been checked for leaks thoroughly?
Any bubbles in the fuel feed between tank and carb when tank is half full to full is not good.
Unstable fuel mixture tuning and blowing glow plugs is a classic sign of bad bearings causing a crankcase pressure leak. Post pics of these “blown” glow plugs. As clear of a picture of the element itself as possible. It’s easy to spot.
What engine is it?
How is the pinch? How much fuel has the engine seen (realistically)?
What fuel is being used? (Nitro/oil/fuel brand)?
Glow plug brand and heat range / plug #?
Has the fuel system been checked for leaks thoroughly?
Any bubbles in the fuel feed between tank and carb when tank is half full to full is not good.
Unstable fuel mixture tuning and blowing glow plugs is a classic sign of bad bearings causing a crankcase pressure leak. Post pics of these “blown” glow plugs. As clear of a picture of the element itself as possible. It’s easy to spot.
02-04-2019, 06:41 PM
#8
Originally Posted by illmatic94
you would think it was that simple . Nothing fixed it. Was constantly fat until the crank cleared then immediately overheated or cut out from NO fuel .
02-04-2019, 08:35 PM
#10
A partial blockage of the fuel or pressure line does sound plausible. Alternately the compression ratio could be wrong. If the compression is too low, you'll have to lean-out the HSN too much just to get power; if the compression is too high, you'll have to enrich the LSN and possibly also the HSN to the point that the engine bogs-down frequently just to keep it from overheating. If thoroughly cleaning the fuel system doesn't help, try adding another shim to the shim stack, because it sounds to me like the compression ratio might be a touch too high.
02-04-2019, 08:37 PM
#11
Originally Posted by E1 Diablo
I've seen this happen when the tank / fuel line isn't getting pressurized. You can richen the HSN all day... you pull the throttle, engine will clear, lean out, starve itself for fuel, and flame out.
02-04-2019, 08:38 PM
#12
Originally Posted by fyrstormer
A partial blockage of the fuel or pressure line does sound plausible. Alternately the compression ratio could be wrong. If the compression is too low, you'll have to lean-out the HSN too much just to get power; if the compression is too high, you'll have to enrich the LSN and possibly also the HSN to the point that the engine bogs-down frequently just to keep it from overheating. If thoroughly cleaning the fuel system doesn't help, try adding another shim to the shim stack, because it sounds to me like the compression ratio might be a touch too high.
02-05-2019, 06:02 AM
#13
Tech Regular
iTrader: (4)
Originally Posted by SlowLST2
An engine cannot be rich and lean at the same time. It’s just not possible.
What engine is it?
How is the pinch? How much fuel has the engine seen (realistically)?
What fuel is being used? (Nitro/oil/fuel brand)?
Glow plug brand and heat range / plug #?
Has the fuel system been checked for leaks thoroughly?
Any bubbles in the fuel feed between tank and carb when tank is half full to full is not good.
Unstable fuel mixture tuning and blowing glow plugs is a classic sign of bad bearings causing a crankcase pressure leak. Post pics of these “blown” glow plugs. As clear of a picture of the element itself as possible. It’s easy to spot.
What engine is it?
How is the pinch? How much fuel has the engine seen (realistically)?
What fuel is being used? (Nitro/oil/fuel brand)?
Glow plug brand and heat range / plug #?
Has the fuel system been checked for leaks thoroughly?
Any bubbles in the fuel feed between tank and carb when tank is half full to full is not good.
Unstable fuel mixture tuning and blowing glow plugs is a classic sign of bad bearings causing a crankcase pressure leak. Post pics of these “blown” glow plugs. As clear of a picture of the element itself as possible. It’s easy to spot.
02-05-2019, 07:54 AM
#14
Originally Posted by sebtarta
Again what engine is this? Change all fuel lines, exhaust seals, glow plug, air filter. Make sure carb is not loose either. Set needles to factory and start over.
02-05-2019, 10:50 AM
#15
Originally Posted by illmatic94
I don’t believe the engine brand would change any of the symptoms. It’s a Losi 454. I’ve changed everything . There’s no leaking bearings either.
