A25A-FXS Engine Breakdown Graphic and Operation Description
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From: Niagara Falls, Ontario
A25A-FXS Engine Breakdown Graphic and Operation Description
For those technically inquisitive folk here's some great details on engine family found in the 2nd gen NX and RX family
Found this graphic series on Toyota's A25 series engines, here is the main site:
https://toyota-club.net/
Toyota engines - A25·M20 - Dynamic Force series (R4):
Shows the Lubrication system and more importantly the pump operation details describing the: "Trochoidal pump is driven via an additional short chain. The ECM controls the pump operation by oil pressure control valve, depending on the engine temperature, speed and other parameters."
https://toyota-club.net/files/faq/18..._df_r4_eng.htm
Found this graphic series on Toyota's A25 series engines, here is the main site:
https://toyota-club.net/
Toyota engines - A25·M20 - Dynamic Force series (R4):
Shows the Lubrication system and more importantly the pump operation details describing the: "Trochoidal pump is driven via an additional short chain. The ECM controls the pump operation by oil pressure control valve, depending on the engine temperature, speed and other parameters."
https://toyota-club.net/files/faq/18..._df_r4_eng.htm
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Joined: Dec 2012
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From: Toronto, ON
One of my favourite sites, loads of technical information across all Toyota engines, transmissions, fluids, models, AWD systems, etc. I can only assume a lot of this information has been skimmed from the service manuals or perhaps internal technical documents. Those of you that watch TCCN Youtube videos a lot will sometimes recognize the diagrams he uses as being the same provided here. The info is not always completely up to date, but I've yet to find any place that does better without a subscription fee.
Last edited by Droid13; Jan 16, 2025 at 01:16 PM.
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At this point moving forward with 2023+ models they should be fairly reliable correct? Seems like Toyota is putting them in almost their entire lineup so the design must be dialed at this point. Assuming the EGR fix comes from the factory on 2023+ models
Last edited by endocrinoo01; Aug 16, 2025 at 04:01 PM.
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Joined: Dec 2012
Posts: 2,129
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From: Toronto, ON
To what 23+ EGR fix for the A25A engine do you refer to? I've not heard of any serious issues related to EGR in this engine. The previous generation Lexus CT and Prius were notorious for intakes clogging up due to EGR but the D4S engine design thru most Toyota engines over the last 8 yrs has greatly reduced the impact of EGR on those engines that have it (the Turbo model doesn't have one at all). But aside from that, the A25A engine has been quite reliable since it first showed up I think in 2017 or 2018, a few minor issues the first couple years. So yea, decent engine but alas, the A25A engine is pretty much already obsolete, smaller, more efficient, more powerful engines on the way to replace these "dinosaurs", LOL.
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jdanielca
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