MOP Adjustments
07-03-2007, 10:44 AM
#26
The set screw controls minimum flow. It is adjustable, but I don't know what the net effect would be.
The relative saw arm to drive gear position is irrelevant since it is continuous. It is the servo function of the position sensor that gives it meaning.
The position sensor is not a switch. It is a pot and provides a position feedback function to the PCM.
I wish the damn OMP was in a more easily accessed position so I could play with all of the possibilities without hurting my back.
The relative saw arm to drive gear position is irrelevant since it is continuous. It is the servo function of the position sensor that gives it meaning.
The position sensor is not a switch. It is a pot and provides a position feedback function to the PCM.
I wish the damn OMP was in a more easily accessed position so I could play with all of the possibilities without hurting my back.
07-03-2007, 11:25 AM
#27
the enemy in the mirror
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true that the position sensor gives it meaning, but wouldn't adjusting the saw arm or gear independently of one another skew the actual setting? it would mean that when the position sensor reported to the ecu that the mop was at setting "1" it would really be set to "2"...?
07-03-2007, 11:33 AM
#28
No, it would just continue to turn the motor until it hit the stop screw and set that position as zero.
This is why it is a long shot that setting the range of the position sensor to something higher than the OEM setting will yield a greater output since the PCM calibrates minimum on its own.
Perhaps a greater stop crew setting coupled with a position sensor turn is required for the desired effect.
This is why it is a long shot that setting the range of the position sensor to something higher than the OEM setting will yield a greater output since the PCM calibrates minimum on its own.
Perhaps a greater stop crew setting coupled with a position sensor turn is required for the desired effect.
07-03-2007, 11:37 AM
#29
Registered
07-03-2007, 12:31 PM
#30
That is the position sensor.
I don't know why it is labeled a "switch" on the diagrams, but it is a pot and passes a variable resistance based on position.
If the PCM only uses this resistance to show that the OMP has moved off of its stop, then it will be useless as an adjuster.
However, the tech training material refers to this system as a servo, which means a full-control feedback loop.
I don't know why it is labeled a "switch" on the diagrams, but it is a pot and passes a variable resistance based on position.
If the PCM only uses this resistance to show that the OMP has moved off of its stop, then it will be useless as an adjuster.
However, the tech training material refers to this system as a servo, which means a full-control feedback loop.
07-03-2007, 01:37 PM
#32
07-03-2007, 02:00 PM
#34
Not really.
Take a look at how the rings and seals on the rotors work in conjunction with the ports.
For blowby to substantially raise the oil level on the Renesis would require almost a complete failure of the cutoff ring.
People that are exhibiting an increase in oil level during normal operation are experiencing something else.
Take a look at how the rings and seals on the rotors work in conjunction with the ports.
For blowby to substantially raise the oil level on the Renesis would require almost a complete failure of the cutoff ring.
People that are exhibiting an increase in oil level during normal operation are experiencing something else.
07-03-2007, 02:51 PM
#35
Got Another Rotary
Example - For someone who does a lot of city driving; ever notice the oil level never dropping (or very little) looking like you don't use any oil; and if you take a long trip (3-5 hundred miles - or track the car), that at the end of it it looks like you used a lot of oil as your oil level has dropped a bunch (a quart or more); that will be mostly from condensation burnoff with less than thought actual oil usage. This occurs because mostly city driving never gets the oil hot enough, long enough, to get rid of the moisture and provides the appearance of no oil burning or actual gains until you do a long trip or have a track day to burn off the moisture that collects.
This is just one of the reasons that it is very difficult to accurately measure oil usage in an 8 unless you have a separate tank - and even then the oil in the tank can collect some moisture over time if not used timely.
Last edited by Jax_RX8; 07-03-2007 at 02:56 PM.
07-03-2007, 05:50 PM
#37
all of this is of great interest---i wonder why racing beat went the way it did on omp modification. Do they know something we dont? Probably. Do the good folks working with this know something RB doesn't----maybe.
Would it be easier to just do the mechanical thing with the jets?
olddragger
Would it be easier to just do the mechanical thing with the jets?
olddragger
07-03-2007, 11:52 PM
#41
if you run the older turbo engines rich, and dont have a good pcv setup, the oil gets diluted with gasoline, and the level on the dipstick will stay the same or go up slightly. the extra cutoff seal in the renny, in theory fixes this
07-04-2007, 12:09 AM
#42
Plus, any blow-by on the compression stroke is going to go out the intake port and any on the power stroke will go out the exhaust port.
Those are uncovered by the side seal as it goes by. One or the other is almost always "open" inside the side seals.
Only at TDC are no ports available to the sides of the rotor.
At the point of maximum dynamic pressure, the exhaust port is exposed to the side of the rotor, inside the side seal.
Those are uncovered by the side seal as it goes by. One or the other is almost always "open" inside the side seals.
Only at TDC are no ports available to the sides of the rotor.
At the point of maximum dynamic pressure, the exhaust port is exposed to the side of the rotor, inside the side seal.
Last edited by MazdaManiac; 07-04-2007 at 12:16 AM.
07-04-2007, 02:04 AM
#43
2005 Ti Gray RX-8 - SOLD
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In any case, assuming a working MOP, and even given the possible differences from car to car on how much oil is actually delivered on an absolute scale, it sure would be neat to have a sCANalyzer or electro-mechanical gauge to see MOP performance in real time wouldn't it? Any 'tappable' PCM signal available to feed such a gauge or gauge driving circuit? Just brainstorming...
07-04-2007, 02:21 AM
#45
All the PCM knows is the position of the stepper motor in the pump. It would be nice to know actual flow values.....
And even nicer to know the load/?? values the PCM uses to decide how much oil to inject.
Maybe the Cobb guys have had a look at that table
And even nicer to know the load/?? values the PCM uses to decide how much oil to inject.
Maybe the Cobb guys have had a look at that table
07-04-2007, 06:36 AM
#47
Registered
From the information provided so far, it seems that to get a higher flow without maching things is to:
- crank the stop screw down so that the reference zero is at a higher flow,
- rotate the sensor the same effective angular distance in the same direction.
As far as the control system is concerned, nothing has changed but in reality there is an offset to higher flow for all position settings.
How much oil flow is involved? In a steady run, say a liter is burned every 1800 miles. Traveling at 60 mph, that's about 0.56 cc per min. If the gas milage is 4 liters per 20 miles, 360 liters of gas would be consumed which is the gas to oil ratio.
It would seem almost impossible to blindly control (because there is no feedback on actual flow) a flow of a few drops per min through a needle valve under engine pressure (~50psi). The actual orifice size must be really small and any change in this (dirt, wear) could greatly affect flow. Also because the oil moves so slowly, it's temperature must be more reflective of the engine bay temperature rather than the temperature of the engine itself. The oil viscosity changes significantly over the ambient temperature ranges these cars can operate in, and so presumably would the flow characteristics.
Maybe the flow is on/off rather than steady. For one thing it would help clean out any debris.
- crank the stop screw down so that the reference zero is at a higher flow,
- rotate the sensor the same effective angular distance in the same direction.
As far as the control system is concerned, nothing has changed but in reality there is an offset to higher flow for all position settings.
How much oil flow is involved? In a steady run, say a liter is burned every 1800 miles. Traveling at 60 mph, that's about 0.56 cc per min. If the gas milage is 4 liters per 20 miles, 360 liters of gas would be consumed which is the gas to oil ratio.
It would seem almost impossible to blindly control (because there is no feedback on actual flow) a flow of a few drops per min through a needle valve under engine pressure (~50psi). The actual orifice size must be really small and any change in this (dirt, wear) could greatly affect flow. Also because the oil moves so slowly, it's temperature must be more reflective of the engine bay temperature rather than the temperature of the engine itself. The oil viscosity changes significantly over the ambient temperature ranges these cars can operate in, and so presumably would the flow characteristics.
Maybe the flow is on/off rather than steady. For one thing it would help clean out any debris.
Last edited by Delmeister; 07-04-2007 at 06:44 AM.
07-04-2007, 07:22 AM
#48
Metatron
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Theoretically......
It is still only a theory that the servo takes a "reference zero" from the stopscrew......it has never been observed, nor is there any evidence of the ECU self-calibrating the sensor in that fashion.
.....it's just a theory until someone 'scopes it in action.
S
.....it's just a theory until someone 'scopes it in action.
S
07-04-2007, 07:59 AM
#50
Registered
Although not entirely relevant, as far as I know all stepping motor systems have a home position for reference.
Edit: The comment I made about the sensor is incorrect. Once fixed to the frame, the sensor indicates absolute sector gear position just as the stop screw does. It's primary drawback is that it is electrical and more easily displaced than the stop screw. Movement of either one gives indication of position from the new location. Move them both the same amount in the same direction and the ECU doesn't know anything was changed (I think).
Last edited by Delmeister; 07-04-2007 at 12:17 PM.