Mythbuster: The S5 full range TPS is not used for OMP control.
05-13-10, 11:06 AM
#1
Mythbuster: The S5 full range TPS is not used for OMP control.
Based on Mazda's SAE paper about the S5 (which I recently acquired, PM me if interested) this is a widely-circulated myth. In fact, throttle position is not used at all for OMP calculations on the s5. Mazda specifically chose NOT to use throttle position as part of the calculation because it resulted in unnecessary oil consumption.
It appears that Mazda used the full range TPS to reduce stumbles and improve response as you open the throttle. The SAE paper discusses a new control strategy for this tip-in fuel (acceleration enrichment or throttle pump). The strategy appears to add a single asynchronous (batch fired, outside of the normal injector firing order) pulse from the injectors.
The fuel pulse is calculated in part by the rate of throttle opening. That type of tip-in fuel is used on most modern OEM systems, including the Rx-8:
I suspect the full range TPS is used for the acceleration enrichment/throttle pump calculation, and it may also be used as part of the s5's OEM electronic boost control system. The FD service highlights document specifically says that the full range TPS is used for boost control:
Just to review: The s5 OMP delivers oil based on the AFM signal, not the full range TPS. The full range TPS is used so that the ECU can more effectively deliver fuel as the throttle opens in order to improve response. The full range signal might also be used for the factory boost control system.
It appears that Mazda used the full range TPS to reduce stumbles and improve response as you open the throttle. The SAE paper discusses a new control strategy for this tip-in fuel (acceleration enrichment or throttle pump). The strategy appears to add a single asynchronous (batch fired, outside of the normal injector firing order) pulse from the injectors.
The fuel pulse is calculated in part by the rate of throttle opening. That type of tip-in fuel is used on most modern OEM systems, including the Rx-8:
I suspect the full range TPS is used for the acceleration enrichment/throttle pump calculation, and it may also be used as part of the s5's OEM electronic boost control system. The FD service highlights document specifically says that the full range TPS is used for boost control:
Just to review: The s5 OMP delivers oil based on the AFM signal, not the full range TPS. The full range TPS is used so that the ECU can more effectively deliver fuel as the throttle opens in order to improve response. The full range signal might also be used for the factory boost control system.
Last edited by arghx; 05-13-10 at 11:11 AM. Reason: Rx-8
05-13-10, 12:21 PM
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Good stuff! my copy opens right to the second part....
05-13-10, 12:28 PM
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Very nice info!
One thing, in this paper you posted up, it reads "the amount of oil is measured according to plunger rotation" are they referring to the TPS plunger? If they are, than that would mean that the TPS does play a part in how much oil the OMP injects. It seems that the S5's do also take into account the info from the AFM, engine temp, and RPM, which the S4's do not.
This is the paper I am referring to:
One thing, in this paper you posted up, it reads "the amount of oil is measured according to plunger rotation" are they referring to the TPS plunger? If they are, than that would mean that the TPS does play a part in how much oil the OMP injects. It seems that the S5's do also take into account the info from the AFM, engine temp, and RPM, which the S4's do not.
This is the paper I am referring to:
Last edited by -Crash-; 05-13-10 at 12:38 PM.
05-13-10, 12:35 PM
#4
I think they are referring to the plunger in the pump assembly. Here's a breakdown of a series 6 FD OMP from a 3rd gen thread:
The Parts and what they do:
see https://www.rx7club.com/showthread.p...99#post9870699
also https://www.rx7club.com/3rd-generation-specific-1993-2002-16/omp-declassified-part-ii-895388/ for a discussion of the way the series 6 FD controls the Denso OMP (FD doesn't have an airflow meter so it can't be directly based on airflow)
here's a thread on the 99 spec Mikuni OMP https://www.rx7club.com/3rd-generation-specific-1993-2002-16/omp-declassified-part-iii-mikuni-897507/
The Parts and what they do:
- Linear Stepper Motor - this simply steps a plunger in and out. How far the plunger is in or out is based upon the ECM commanded position.
- Valve Positioner - This moves in and out based upon the position of the linear stepper motor. It is in contact with the motor armature. The spring maintains contact with the motor armature. There is a "slope" or taper cut into the positioner which, depending upon where the motor has it positioned, will change the length of the Worm Driven Gear and Sector Valve stroke.
- Worm Drive Gear and Worm Driven Gear - This is driven from the engine. It rotates the sector valve to align the oil holes with either the oil supply or oil discharge in the OMP body. The worm drive gear and worm driven gear rotate at all times the engine is running. The worm driven gear has two cam followers; as the gear rotates it moves up and down. The followers ride on the Valve Positioner.
- Sector Valve and Sector Valve Needle - The sector valve is keyed to the worm driven gear and rotates in the housing bore at all times when the engine is running. The Sector valve also moves up and down by the two cam followers on the Driven Gear. The stroke length of the sector valve is determined by the where the followers track on the Valve Positioner tapered area. The Sector Valve’s ports rotate to align with either oil fill ports or oil discharge ports. As the sector valve moves down in the bore the fill ports are aligned and oil is drawn into the Sector Valve / Needle bore. The Sector valve continues to rotate and then begin to move up on the cam causing the needle to move into the bore of the sector valve and compressing the oil previously drawn in. At this time the sector valve holes are aligned with the OMP discharge ports and oil is forced to the engine.
- Position Transmitter - The transmitter is a linear 0 to 5 volt feed back to the ECM. It's sole function is to measure the position of valve that the linear stepper motor has set the valve. It is in contact with a tab that is a part of the valve positioner.
also https://www.rx7club.com/3rd-generation-specific-1993-2002-16/omp-declassified-part-ii-895388/ for a discussion of the way the series 6 FD controls the Denso OMP (FD doesn't have an airflow meter so it can't be directly based on airflow)
here's a thread on the 99 spec Mikuni OMP https://www.rx7club.com/3rd-generation-specific-1993-2002-16/omp-declassified-part-iii-mikuni-897507/
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05-13-10, 09:18 PM
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05-13-10, 11:02 PM
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^lol at felix for thinking he took that screenshot right when he posted that in '08. Never know when you might need proof of a post huh?lol. j/k
thats good to know, even though I have an s4. Would this make the S5 engine better in terms of oiling compared to an s4? to clarify, would the s5 system waste less fuel, be smoother, less chance of detonation/ping, things like that. when I go t2 I'll be running premix but I'm curious.
thats good to know, even though I have an s4. Would this make the S5 engine better in terms of oiling compared to an s4? to clarify, would the s5 system waste less fuel, be smoother, less chance of detonation/ping, things like that. when I go t2 I'll be running premix but I'm curious.
05-13-10, 11:49 PM
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^lol at felix for thinking he took that screenshot right when he posted that in '08. Never know when you might need proof of a post huh?lol. j/k
thats good to know, even though I have an s4. Would this make the S5 engine better in terms of oiling compared to an s4? to clarify, would the s5 system waste less fuel, be smoother, less chance of detonation/ping, things like that. when I go t2 I'll be running premix but I'm curious.
thats good to know, even though I have an s4. Would this make the S5 engine better in terms of oiling compared to an s4? to clarify, would the s5 system waste less fuel, be smoother, less chance of detonation/ping, things like that. when I go t2 I'll be running premix but I'm curious.
05-14-10, 01:36 PM
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06-08-11, 12:28 AM
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Another thing the s5 full range TPS was used for: controlling the shift points on the electronically controlled automatic transmission.
The s4 transmission was not electronically controlled and shift points were controlled by engine vacuum, governor pressure, etc.
The s4 transmission was not electronically controlled and shift points were controlled by engine vacuum, governor pressure, etc.
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