kiska3463

Just wondering what you guys think about NX350h 2.5l engine noise when accelerate?
Sometime when you first start driving is super smooth then you can hear that roar when accelerate
Is this normal with this engine?
For price we are paying I dont think I like that "old truck" sound
Thanks

AM123

Owners of the NX350h, unfamiliar with Toyota hybrid powertrains, may experience an unexpected increase in engine noise during acceleration. This contrasts with the quiet operation typically associated with hybrid vehicles.

The primary factor contributing to this phenomenon is the unique planetary gear system employed by Toyota hybrids. This system prioritizes fuel efficiency by maintaining the engine in its optimal operating range during cruising speeds.

However, under rapid acceleration, the planetary gear system requires a brief moment to adjust its gear ratios for increased power demands. This temporary adjustment can result in a temporary elevation in engine RPM, leading to a more noticeable engine sound. While some automotive journalists have compared this sound to household appliances 😅, it is a characteristic of the Toyota hybrid powertrain and not necessarily indicative of a malfunction.

The sound may be perceived as less refined than expected, particularly considering the vehicle's price point. Nonetheless, it is a facet of the hybrid driving experience. Some speculate that the engine noise might be intentionally amplified within the cabin to create a sense of sportiness. Lexus, known for its focus on cabin comfort, might consider incorporating additional sound insulation in future models to address this feedback and provide a quieter driving experience. (Hopefully) 🤞

Droid13

The A25A engine is known for being kind of noisy in all the different models it ends up in and as AM123 nicely points out, it can be somewhat more noticeable in hybrids due to the more steady rpms. The good news is that this engine has now been around for a number of years now and as a group they generally seem to be holding up well.

midcow3

I think it is the Atkinson cycle that makes the noise. However, the Toyota/Lexus hybrid engines tend to be very durable.

An Atkinson-cycle engine is a type of internal combustion engine that uses a modified valve timing to improve efficiency1234. The engine reduces the compression ratio by allowing some intake air to flow back into the intake manifold, but maintains the same expansion ratio134. This means that the engine uses less fuel during the suction stroke, but generates the same power during the power stroke

Oh Yah, Happy Easter.

YMMV,
MidCow3

AM123

[QUOTE=midcow3;11698229]I think it is the Atkinson cycle that makes the noise. However, the Toyota/Lexus hybrid engines tend to be very durable.

An Atkinson-cycle engine is a type of internal combustion engine that uses a modified valve timing to improve efficiency1234. The engine reduces the compression ratio by allowing some intake air to flow back into the intake manifold, but maintains the same expansion ratio134. This means that the engine uses less fuel during the suction stroke, but generates the same power during the power stroke

Oh Yah, Happy Easter.

YMMV,
MidCow3[/QUOTE

Happy Easter midcow3!
The thread seems to be looking for an explanation for the increased engine noise during acceleration in the Atkinson cycle A25A engine, also known as Toyota's dynamic force engine. While the A25A is known for its durability and reliability based on its track record so far, the planetary gear system might contribute to the more noticeable noise when accelerating.
There are a couple of reasons why the A25A engine in a hybrid application might be perceived as slightly noisier than a traditional gasoline engine:
* Engine operation: Hybrid vehicles rely more on electric propulsion, so the engine runs less frequently and for shorter durations. When it does turn on, it might rev higher to compensate for the time it wasn't running, potentially producing more noticeable noise during acceleration.
* Direct injection: When A25A engines use direct injection, which can inherently be slightly louder than port injection due to the high pressure involved.
However, it's important to remember that the cabin noise in a hybrid is generally quieter overall because the engine isn't constantly running.

TheCDN

It's funny, I had an '09 Murano and put over 385,000 kms on it. Yes this was a bad year for cvt's in Murano's but after mine was replaced under an extended warranty claim, it went on to have no problems at all. I got very use to that feeling of a 'gear-less' transmission and the constant pull from the engine. I know that in later years Nissan and others introduced a 'fake' stepping action into their cvt's so it felt like a normal transmission. I had a chance to drive a '23 NX350 turbo with a regular 8 speed transmission as a loaner and you know I didn't like it. I've come to like that constant push from a 'cvt' or more correctly in this car an ecvt.

I know the sound you're hearing, and it's a little disconcerting, it's mostly to blame on the direct injection fuel system for the internal combustion engine - ICE. But the battery (torque) push feels like it comes on very quick and gives the ICE time to rev up to 3,000 rpm or so, and then the ICE provides a little more of a push and the noise is terrible but the car certainly get's up and moving quickly enough. I mean Lexus could have thrown a little more money at designing an exhaust note that sounded better, some more insulation for the high pressure direct injection system noises etc. but I'm happy to put my foot in it and not have it hurt my wallet too! I've watched videos from auto reviewers and there are other makes that aren't as smooth with their power delivery with hybrids. I think the Lexus is quite smooth and I've had hardly nothing in the way of 'catching' the transmission with a stutter by hitting the throttle quickly like when you have to get out of the way at an intersection or when turning onto the road from a parking lot exit.