RXOwner

Yesterday while going up a long hill under medium load in the same gear, something having to do with power cycled on and off and on and off. You could feel the increase and decease is power and even see it on the tach. It did it over and over again until I got to the top of the hill and it went to a higher gear. I was holding the gas pedal very still.

Any ideas?

Comfort

I think I read that the RX has port fuel injection to start and then changes to direct injection. Possible that you were bouncing in and out of that transition point.

RXOwner

That could explain it. It was like turning a switch on and off over and over.

Did this recently change as I have never felt this before on my previous RX350 or RX450h. Power was always so smooth.

Comfort

Yes Gen 3 only used port fuel injection. They can probably fix this with fuel map changes. You might complain to CS and/or have the dealer look for a fix. Here's a quote from Lexus on the RX:

The RX 350 has the power to inspire. An enhanced 3.5-liter V6 engine with direct and port fuel injection delivers increased horsepower with advanced fuel economy. With 295 horsepower, the RX 350 entices with a continuous feeling of acceleration. For even greater control, an innovative dual Variable Valve Timing with intelligence (VVT-i) system offers precise engine performance as it reduces emissions and improves fuel economy. VVT-i monitors the engine's speed and load, increasing torque at lower speeds for improved acceleration, and boosts performance at higher speeds by adjusting intake and exhaust valve timing.

RXOwner

Sure sounds good doesn't it!

I am at 6500 miles and hope they can find and fix the problem at the 10K.

bootman

Folks this is the new world of optimum fuel economy.
The cars we drive now will not act like those from the past.
The transmission complaints are based on the same thing.
The computer and not your right foot will determine what your engine does.

RXOwner

I have no problem having a computer controlling things as long as they work correctly.

coolsaber

The conventional 45-psi (3.1 bar) port injection takes care of start-up by itself because it's cleaner and more efficient at doing that, while the high-pressure direct injection operates alone at full load for maximum performance. In between, at most part-load conditions, both operate together (along with the dual VVT-i) to optimize the finely tuned balance of performance, fuel economy and emissions.

With the event you describe as "power cycling" seems it maybe more along the lines of the transmission being caught with its "pants down" and trying to pin the engine at the correct RPM. You were on a hill, with steady accelerator pressure, although I assume your vehicle speed was going down, tach decreasing.

TLR Normal behavior in the position since its trying to figure out whether to switch down or up and also change VVTi profiles

RXOwner

I know the difference. It is not the transmission as I can push it in manual at say 4th gear, 2700rpm and under medium to light load and it does it. Speed is not going down, tach NOT decreasing but pulsing at 200rpm up and down in a little less than a second. Then power changes slightly like flipping a switch on and off over and over to the point you can see it on the tach and feel it.

bootman

As long as you get the maximum fuel economy, it is "working correctly".
But that still doesn't mean it will feel "normal".

Put the car in sport and the shiftier in manual at 4 and try the same road.
If it "feels" better then, I'll bet you are getting worse fuel economy.

Who is right now?

Comfort

I'm with RXowner, it's not acceptable to have a new car surging-ever. Dealers are the first to blame things on EPA regs. There are more complicated systems that are seamless. Either Lexus missed this in testing or something like a bad component is causing the issue. Look at the new Volvo engine for comparison-Electric supercharger transitioning to turbo. How about a twin scroll turbo on a direct injected engine. Most all of these new engines also have variable valve timing and some with cylinder deactivation. Lexus isn't going to knowingly send out an engine that isn't first class, IMO. And this isn't the first year for port/DI engines, they had them in at least one car last year.

coolsaber

Easy then. Take it into the dealership and get a service record. Best you can do on that issue and see if you can replicate on a similar vehicle. Without field reports Lexus won`t recognize a defect if there is one.

coolsaber

Damn go hard or go home right?


Anyways what Volvo has an electric supercharger? The current SPA twin charged's supercharger is mechanical.

Lexus and the Toyota group has been doing the port and direct injection with the advent of the D4-S moniker so they are not in unexplored grounds.

Comfort

Here's the Volvo engine Review by Car and Driver- 450 HP 2 liter engine coming soon....
The engine uses a 48-volt electric supercharger that sits upstream of twin BorgWarner turbochargers, and which is fed by a supercapacitor power pack sitting in the trunk. The supercharger doesn’t feed the cylinders directly except incidentally, working instead to pre-charge the air before it reaches the turbos and helping to spool them up and reduce lag. The turbos themselves are plumbed in parallel, with one breathing gases expelled by cylinders two and three and the other getting spun by cylinders one and four. Each delivers up to 50 psi of boost and peak power arrives at 6500 rpm, relatively high for a modern turbo. Unsurprisingly, the fueling system needs high-flow injectors and twin fuel pumps to keep up.

ccb777

I have a BMW that had a lag when you first accelerated. They put new software that corrected that. Hopefully Lexus can put new software to correct this problem.

On the Volvo engine with supercharger and turbo-I wonder if that engine will last 200,000 miles. I do believe the Lexus engine will do that with no problem. I worry about my BMW with a turbo, It has already had one recall.

Look forward to seeing how reliable my wife's RX will be and if there are gliches how Lexus will solve them.