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Mythbuster: The S5 full range TPS is not used for OMP control.
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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.
https://www.rx7club.com/attachment.p...1&d=1273765573 https://www.rx7club.com/attachment.p...1&d=1273765942 https://www.rx7club.com/attachment.p...1&d=1273765573 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. https://www.rx7club.com/attachment.p...1&d=1273766318 https://www.rx7club.com/attachment.p...1&d=1273766318 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: https://www.rx7club.com/attachment.p...1&d=1273767094 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: https://www.rx7club.com/attachment.p...1&d=1273766671 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. |
Good stuff! my copy opens right to the second part....
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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: https://www.rx7club.com/attachment.p...1&d=1273765573 |
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:
Originally Posted by ttmott
(Post 9870699)
The Parts and what they do:
https://www.rx7club.com/picture.php?...ictureid=21866 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/ |
Your right! this is really good stuff to know.
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Nice! And it just so happened my OMP and ECU just gave up the ghost, so good to know!
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FYI the 2009+ Rx-8 OMP design is completely different from all earlier OMP designs. It works a lot like a returnless fuel system.
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Very interesting. :icon_tup:
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I more or less caught on to this May of '08. See the attached jpg.
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I never would have known about this if you didnt post it, thanks!
Edit: Hailers, how did your post count only go up +3 from may 08 to now? lol |
Originally Posted by FelixIsGod29X
(Post 9995113)
I never would have known about this if you didnt post it, thanks!
Edit: Hailers, how did your post count only go up +3 from may 08 to now? lol |
^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. |
Originally Posted by FC_fan
(Post 9995368)
^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. |
Originally Posted by -Crash-
(Post 9995138)
lol whenever you post it updates all of them, he took that screen shot 3 posts earlier...
Even though Mazda did a lot of R & D why is it that S4 n/as last longer than S5 n/a's? At least it seems S4 N/A last longer IMHO. |
Originally Posted by j9fd3s
(Post 9995462)
there is another part of the paper where they examine the apex seal temps, and they decided that they could use less oil and get the same results. or to put it the other way the s4 uses more oil for the same results as the s5.
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Originally Posted by arghx
(Post 9996418)
those tests were done at stock power levels though.
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Another thing the s5 full range TPS was used for: controlling the shift points on the electronically controlled automatic transmission.
https://www.rx7club.com/attachment.p...1&d=1307510532 The s4 transmission was not electronically controlled and shift points were controlled by engine vacuum, governor pressure, etc. |
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