The pump is driven via the exhaust camshaft at least on engines I've seen. What else is involved in this system?

 

Similar reason here. The variable cam timing is used to cause some of the intake charge to go back into the intake manifold, reducing the compression ratio and need for restrictions in the manifold which would increase pumping losses. Basically, the cams and intake valves do some of the work of the throttle valves.

 

Yes - it has already been around for more than 7 years, however don't expect it to be as trouble-free as the one that it replaced (2AR-FSE). To me, apart from fuel economy the 2AR is still a more refined engine and makes less noise than the DF engines.

Compiled by Toyota-Club.net (the list is already much longer than the 2AR-FXE)

Issues were:

[1] The first defect recognized by the manufacturer: an incident with oversized A25 pistons that once was supplied to the TMMK conveyor (Toyota recall J1M / J0M, NHTSA 18V200000).

• [2] The second case is also related to the North American market - total recall of cars with A25, produced in sep-dec 2019, due to a "possible" defectous cylinder block casting (Toyota recall 20TA04, NHTSA 20V064).

But let’s remind again... The renowned reliability of Toyota engines is built entirely on simple solutions, archaic designs and proven technologies. Deviation from these rules in most cases leads to sad results. A25 is perceived as the successor to the very successful 2AR-FE, but, evaluating the combination of new solutions and and "improvements", it can be guaranteed - the new motor will certainly not be as reliable and trouble-free.

So far, the main trouble of the DF engines - quite unexpectedly - it is their excessive noise. Causing discomfort at medium rpms, at the high it destroys the driver’s patience (especially unpleasant voice of A25). For hybrids, the problem is not so significant, since their internal combustion engine less time runs at high rpms, but traditional automatic transmissions and CVTs do not miss the opportunity to hold the tachometer needle at the top of the scale. This flaw seems small, but in real it may be the last decisive argument against the choice of Toyota car.


• [3] For some A25A-FKS engines manufactured before 2018/02, recall campaign 21SMD-088 (17.11.2021) has been announced - replacement of the vacuum pump vane and vane caps (29331-25010, 29329-25011).


• [4] The official regulator published a notice (10.12.2021) on a recall campaign for almost a million cars of Chinese domestic market produced in 2017-2020 (RAV4/Wildlander, C-HR, Camry, Izoa, Avalon, UX, ES). The declared problem is a corrosion of the EGR valve (supposedly caused by high chlorine content in the fuel), which can lead to its sticking and engine unstable operation, thereby affecting road safety. Prescription - replacement of at least the EGR valve with a modified one (a composite valve body instead of an all-aluminum).

• [5] The bad news for European car owners: Toyota has refused to treat numerous problems with the EGR cooler as a design defect and a warranty claim.


As known, due to the destruction of the EGR cooler heat exchanger, coolant ingress the EGR channels and then into the cylinders. At the same time, abundant deposits (in the form of powder or crystals) form in the gas channels, often the EGR valve sticks. External symptoms - white smoke from the exhaust pipe, engine hesitation and power loss, the appearance of DTC codes (P319000, P04019C etc.), antifreeze level drops and engine overheat is possible. All this take place on cars rather new and at rather low mileage.


In general, the reason is clear - since the new generation (Dynamic Force) Toyota began to equip all the gasoline engines with high-performance EGR systems with water cooling, but did not provide for the necessary durability and corrosion resistance for real operating conditions. EGR coolers have long been used in diesel models, and internal heat exchanger leaks also occur there, but such cases are much less resonant (besides, fatigue cracks covered by the warranty are among the reasons).


However, in this case, Toyota decided to consider corrosion due to using of low-quality gasoline with an admixture of chlorine compounds as the cause and set out its position in the latest TSB EG-00691T-TME (02.02.2022). Repairs should be paid by the owners (the usual bill in S.Europe was $1500 as of 2021), but regional offices can provide a discount. At the same time, the service life of the new EGR cooler is also completely unpredictable.

• [6] An interesting feature of the A25 and M20 engines was revealed in the American market (not a warranty case, described in T-SB-0104-21 of 17.12.2021).


Problem: engine oil emulsion (milky/discolored), 'Oil Pressure Low' message and DTCs P05202A and P052477 may appear. Cause: during short trips at freezing temperatures, abundant condensation of moisture from blow-by gases occurs, which under such conditions is not removed naturally (evaporation after warming-up to normal operating temperatures).


Prescription: ensure the emulsion did not appear as a result of coolant leak; check for DTC during warming-up to 50°C; replacement of engine oil and filter; remove all traces of emulsion residue.

Later, a corresponding TSB for the European market appeared - EG-00731T-TME (11.04.2022).

• [7] M20 engine oil level sensor malfunction (described in EG-00852T-TME of 09.11.2022).

• [8] Fuel odor from the high-pressure fuel pump (described in T-SB-0008-23 of 26.01.2023 and customer support program 23TE01).


Problem: fuel odor from engine bay due to seepage from the high pressure fuel pump because of corrosion (A25A engine - Highlander, RAV4, RAV4 HV, RAV4 Prime, Venza, Sienna). Prescription: fuel pump replacement.

 

Problems have arisen. I would imagine that they have been corrected.

 

It's a very complex engine, and overall drive train, as we all know. As WellsB has stated, let's hope that these have been addressed and corrected. Time will tell.

 

For what its worth, the car care nut says its still early to say definitively but he has not seen any tell tale signs that the engine will prove unreliable down the road. In fact it was an honorable mention of his list of all time great toyota/lexus engines.

 

We have recently purchased a 2024 RX350h which has 25A-FXS engine. Is this engine turbocharged? The non-hybrid 2024 RX350 engine (25A-FKS) is turbocharged. I am not able to find this information (whether RX350h is turbocharged) in the manual.

Thank you.

 

The 350H (A25-FXS) is non-turbo. Turbo engines model numbers start with "T".

https://en.wikipedia.org/wiki/Toyota...c_Force_engine

The 2024 RX has four engine variations, three of which are hybrid powertrains. The base RX model and the 500H are the only turbo engines. 350H/450H+ are non-turbos.

The base gas powertrain for the RX 350 is a 2.4L I4 turbocharged engine with a horsepower of 275 and a torque of 317 lb-ft. This engine has a standard eight-speed electronically controlled transmission and is available with an FWD or an AWD drivetrain. The acceleration time for this engine is 7.6 seconds for the FWD model and 7.2 seconds for the AWD model.

The RX 350h AWD has a 2.5L hybrid engine with a horsepower of 246 and torque of 233 lb-ft, with a 7.4-second acceleration.

The RX 450h+ has a 2.5L plug-in hybrid engine that produces 304 horsepower, has a 6.2-second acceleration speed, an EPA estimate of 83 MPGe, and a 37-mile all-electric range.

The RX 500h has a turbocharged 2.4L hybrid engine that generates 366 horsepower and 406 lb-ft of torque, with a 5.9-second acceleration speed.