rx4u

Rx400H Pulsating/surging When Driving Around 70 - 80 Mph

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Just picked up a 2008 RX400h and noticed that when crusing on the freeway around 70 to 80 mph, the vehicle begins to pulsate/surge. There is no noticeable decrease or increase of speed, just a subtle pulsation as if I were driving against a strong headwind. Is this a known issue or just a byproduct of the hybrid technology? I have four days left to return it or switch it out and want to be sure before this time period expires. Loving everything esle about the truck. Tremendous vehicle!

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Can't say that I've noticed this on mine, but it's been awhile since I've run it on cruise at that speed. I assume you have it on cruise control when this is happening and that for the most part the gas engine is running. Sounds like a drive with a tech might be in order if you can find a place to recreate that near the dealership.

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My apologies. When I wrote cruisin, I meant just driving, not on actual cruise control.

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Have your dealer check for available reprogramming , there is a TSB that applies to this condition, exactly as you have complained .

I agree; specifically ask to see all tsbs and check to see if all recalled were performed, as well.

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this was happening at 40mph also, prior to the tsb, and the reprogramming corrected it, also have them do an isc reset, if the updates at the dealer have not been done, there is a good chance this needs attention too.

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Thanks all. I appreciate the insight and guidance. I will take it into the dealership to have it checked and report back my findings. Again, thanks a ton.

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Hello,

reviving an old thread, sorry about this 8-/

I own a 2006 euro spec RX400h with a bit more than 255'000 on the clock (that 160'000 miles).

I experienced this yesterday (both "town speed" and "highway speed"), it never occurred before.
I was suspecting the gazoline I put in just before leaving on my trip then found this thread and others on the same subject.

The tank is almost empty so I'll fill it with "better" gas tomorrow and do some tests.

If issue still occurs, do you know how to check if the TSB were properly applied (this car has not seen a Lexus/Toyota shop for two years) and if there's a way of applying them on my own (with Techsteam)?

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The TSB is

EG013-07

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I have the TSB, I found it in another thread. Thank you anyway 8)

My question is about applying the new firmware without going to a Lexus/Toyota shop (I don't trust them. At all. At least the one less than 100 miles from here).

Reading the TSB it appears that, even you get the firmware (how?) you need the Hybrid Battery Charger/Tester plugged in...
I wonder if this is really the case or it's only a way to get owners to go in Lexus/Toyota shops.

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I am afraid these firmware uploads are very proprioritory.  I doubt that you would be able to get them outside of Toyota or Lexus dealerships.

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Quick review about this: refilling the tank fixed the issue...

There might have been something bad (bad dosing? not something that cloaked the gas filter anyway) in previous tank.

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