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Lexus RX 400h Engine Problems

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    roheyrohey Member Posts: 4
    pulsing is gone......They the flash program listed in the TSB and all is fine. Never acknowledged it was a known problem and di not want to have anything to do with the copy of the TSB I brought it????? Oh well the wife's rig is a pleasure to drive again.
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    upstatedocupstatedoc Member Posts: 710
    Looks like it was a bomb...I don't know whats scarier.
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    nmrknmrk Member Posts: 8
    I have a 2006 Lexus 400 hydrid. It surges when I am braking. I do not have a floor mat causing the problem. The problem is intermittent. I have not been able to establish a "pattern of behavior." It always surprises me. I never take my foot off the brake when coming to a stop or slowing down because I don't trust the car NOT to surge. Yes--I have raised the question with Lexus. I am always the ONLY person to have the problem.

    At least I now know there are two of us.
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    wwestwwest Member Posts: 10,706
    What you may be experiencing is "pre-activation" of ABS. Sometimes the anti-lock system detects just a very slight bit of inordinant wheel rotational rate deceleration and the initial action of the anti-lock system will be to INSTANTLY disable regen braking. The "event" is short enough, or the loss of regen braking is effective enough, that full ABS activation does not occur. The brake pressure release solenoid(s) are never activated (no brake pedal ABS "feedback") and so you end up puzzled about just what happened.

    A slight bump in the roadbed, steel plate, even a "plastic" roadway marking, can cause this effect.
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    nmrknmrk Member Posts: 8
    WWest;

    Thank you for your response. Sounds a little technical but I think I understand. In any event, it sounds like I need not be worried about the "little surge". I had read about major surges and was concerned that my problem might be exacerbated. NMRK
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    marmimarmi Member Posts: 3
    to wwest:
    I was thankful to get your message about your surging problem when braking. I also have not been aable to establish a "pattern of behavior" and am paranoid when I come to a stop. My surge led me into a brick wall and was a very costly incident-today I received a new insurance bill that tripled my insurance rate. The dealership checked it out and said it could not have happened the way I described it. I checked my floor mat and of course it was not the problem. I don't know if it will take a terribly unfortunate accident for Lexus to solve this problem, but I am thinking of getting rid of my car, which I love otherwise. I am sure there are not just "the two of us" who have experienced this event.
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    ganjaspliffin1ganjaspliffin1 Member Posts: 1
    I have had this problem with my Lexus RX400H 2006 MANY times. I think this is probably a widespread problem that often goes unreported. I have actually gotten used to this happening. It is intermittant as another respondant had written. This makes it unpredictable so I'm always prepared to brake harder with my foot covering the brake pedal. It seems to happen most often when I'm not trying to come to a complete stop such as slowly rolling through the Easy-pass lane on the thruway toll booths, etc. I have never reported this issue to my Lexus dealer and I haven't had the best trust in them. I'm sure they would blow smoke. I'm having several other problems with this vehicle including trouble starting it with the headlights on AUTO. Also the navigation system won't accept ANY local addresses all of a sudden (says "address does not exist." Poor dealership relatons plus these BUGS in the vehicle made me a dissatisfied LEXUS owner.
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    marmimarmi Member Posts: 3
    Thank you for replying to my post- your problem happened precisely as did mine-mine when rolling to a stop in a parking lane and yours, for instance when rolling through the toll booth lane. I would urge you to report this intermittent problem to your Lexus dealer, if only to establish a paper trail. When I had my surge, I hit a brick building. What if a person or another vehicle were in front of us? I ended up having a point on my driving record which cost me insurancewise-it could, however be much more serious-is your vehicle a hybrid, by the way?
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    wwestwwest Member Posts: 10,706
    I have probably said this before, but...

    These are FWD vehicles, so it is EXTREMELY important not to allow braking of ANY kind, engine, regen, or actual frictional braking, to result in wheelskid/slip and therefore raise the potential for an accident due to loss of directional control.

    To that end VW has just introduced a new engine RPM control design that will automatically up-rev the engine should the driver inadvertently downshift to a level wherein the rotation decline of the front driven wheels is so rapid lockup will soon result.

    So we may now see a resurgence of FWD amd F/awd vehicles with stick shifting.

    "..rolling through a toll booth...."

    Hmmmm....

    Metal expansion joint, slightly WET metal expansion joint.....??

    Or "plastic" road striping, WET "plastic" road striping...??

    Most modern Anti-lock systems are desired to pre-empt wheelskid/lockup by sensing that the wheel(s) rotation rate is decling so rapidly the lockup will soon result. With light to moderate braking and with the hybrid battery SOC being fairly low you may very well be relying on regen braking ENTIRELY.

    If ABS activation is required then regen must first be INSTANTLY cancelled in favor of frictional braking ONLY. For a programmer there is no simple nor easy solution to this problem. The best solution, given the situation, need for ABS due to impending wheel lockup, it seems to me that it would be better/best to bring the frictional braking on line in a moderate way. Previous regen braking level was heading toward wheelskid/lockup, best to bring frictional braking on line at a slightly lower braking level.

    So the driver feels a "lurch" forward.....

    As I have said before, why not disable ABS altogether unless VSC indicates maintenance of directional control, directional correction, is required..?

    The most of those brief instances of low traction due to expansion joints, plastic striping, and "bumps", would be transparent, "non-events".
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    nmrknmrk Member Posts: 8
    I have read your explanations re the surge--but am now confused. What should I do to either deal with or get rid of this surge problem. I haven't run into anything but it worries me. I am also thinking of getting rid of the car. I like it but don't trust it. On the other hand--is this a common problem with cars utilizing similar technology?

    Thanks for your attempt to educate me--but now I am confused.

    NMRK
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    wwestwwest Member Posts: 10,706
    Is it really a surge or more like what I describe, a slight or moderate loosening of braking..??

    A true SURGE forward, actual forward acceleration, would indicate other problems.
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    nmrknmrk Member Posts: 8
    Mr. West:

    My Lexus is resting this week--however, when I next drive it, I will try to ascertain whether I am sensing a "surge" versus, as you suggest, a "loosening of braking." You may be correct that what I am experiencing is loosening of braking. I would never take my foot off the brake to coast into a parking place so should not smash into anything. I had the car checked again at the Lexus dealer and nothing appeared to be abnormal.

    Thank you for replying.
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    billysbarn1billysbarn1 Member Posts: 1
    Here is my pennie's worth!
    I have a 2006 400h and I notice when going down a steep hill, especially when the engine is cold, (but perhaps that is when I hit the first steep hill) that as I am gently braking the regen is putting a nice amount of power back in the battery and the meter is well into the blue, then after a few seconds the braking lifts off for a fraction of a second, the car runs away and the charging stops but the friction brakes kick in.
    However, I think that is because I subconsciously press the pedal slightly harder and all is well again. Then I release the pedal and press gently and regen kicks in again and drops out after a few seconds and the process continues as described above till I get to the bottom of the hill.

    I thought that was normal and happening because the regen wasn't able to provide enough braking but perhaps not....

    I am used to it now and it's no problem to me.

    Enjoy your car.. I do :) I have no intention of changing it for another 10 + years!!

    Billy
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    wwestwwest Member Posts: 10,706
    My '01 AWD RX300 does something strange, "washboardy" road feel, when lightly braking going down a slight grade with the roadbed wet. It's as if the ABS is very lightly modulating the brakes. I seem to remember that someone at the dealer told me that it was the EBD, Electronic Brakeforce Distribution, activating.

    If your "H" has the same EBD feature then it is likely that regen would have to be disabled when it activates.
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    nmrknmrk Member Posts: 8
    Mr. West:

    My car has not been resting all of this time, my mind is.

    It is a surge. I can feel the forward jerk and, so can my sister. She had this problem with her Grand Am.

    I have not been in a situation where I had to brake at high speeds. I should check it out just out of curiosity. I have not established a pattern for this behavior and it is totally intermittent.

    Lexus no longer responds to my emails. I guess they have enough problems. I now have 20,000 miles on the car and must replace the tires.

    Thanks for your help.
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    wwestwwest Member Posts: 10,706
    I should have mentioned that with the RXh, or any of the FWD hybrids, if even the slightest sign of impending lockup of the wheels is detected then regen braking will be INSTANTLY disabled. Brief slippery spot in the roadbed (plastic crosswalk stripping, railway rail, even a slight bump, can result in a tire losing roadbed traction just long enough to force a sudden transition, NON-SMOOTH, transition.

    With light to moderate braking this SUDDEN transition from regen braking, maybe ONLY regen braking, to SOLELY frictional braking might be somewhat JARRING.

    You're body's seat-of-the-pants" sensors cannot easily distinguish between a lessening of the braking force and an actual surge forward. If you were in a flight simulator I could give you the same effect as a surge by suddenly tilting the front of the simulator upward.
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    nmrknmrk Member Posts: 8
    My Lexus serviceman finally gave me a similar explanation on the "surge." I did turn 20,000 miles.

    "You're body's seat-of-the-pants" sensors cannot easily distinguish....."

    Are you saying that the problem is my insensitive rear end? And all the while I thought it was the rear end of the Lexus. I won't even ask why the batteries on my Lexus, Prius and Ford truck go dead if not "walked" regularly. I'd hate to think I have other malfunctioning body parts.

    Thanks.
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    mtrsmtrs Member Posts: 4
    To add to this, I also experience a slight surge when the regen braking suddenly shuts off as I'm approaching a stop. It tends to happen if I'm going over bumps in the pavemen, even when the road's dry.

    Regarding the question of ABS pre-activation, it's possible, but I have another theory: it could be to maximize the life of the power inverters. Toyota may have programmed the regen braking to shut off if it detects any unexpected variation in the current/frequency of the electricity coming from the regen motors. If a wheel were to slip-and-catch, then presumably the voltage/current that are hitting the inverters are varying wildly. This could put a substantial stress on the electric components in the inverter, and shorten their expected lifespan. Hence, Toyota may have programmed the system to shut off if a significant-enough bump is encountered.
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    sunrise241sunrise241 Member Posts: 2
    Ok lets say this it turns over and I have these Key items:
    1) Fuel (Plugs are wet with fuel and noid tester shows Injector Pulse) and fuel at both side of fuel rail.
    2) Spark @ 1.mm with tester and correct timing on spark.
    3) Compression 150-160
    4) New Crank Sensor
    5) timing belt intact and did not jump timing.

    I have done everything I know To do and to check but this is puzzling me? any Lexus or any other techs know what I may have missed.
    Please help
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    sunrise241sunrise241 Member Posts: 2
    Ok lets say this it turns over and I have these Key items:
    1) Fuel (Plugs are wet with fuel and noid tester shows Injector Pulse) and fuel at both side of fuel rail.
    2) Spark 1.mm with tester and correct timing on spark.
    3) Compression 150-160
    4) New Crank Sensor
    5) timing belt intact and did not jump timing.

    I have done everything I know To do and to check but this is puzzling me? any Lexus or any other techs know what I may have missed.

    Please help
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    cvav1615cvav1615 Member Posts: 3
    Hello, I have a 2006 RX400h, with 88,000 miles. Garage kept, single driver, routine maintenance since purchase. I have recently had a significant decrease in fuel mileage and now my car has what sounds like, as best I can describe, either an engine 'hum', or a steady engine sound of high idle, like it wants to shift into a higher gear but never does. This occurs at any speed, 15 or 70, it doesn't matter. The sound never changes regardless of the speed. Anyone else having this issue? Or can anyone suggest or advise what this issue might be? Thanks!
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    mollyt1mollyt1 Member Posts: 1
    My 2006 has about 250k miles... I'm original owner, did all recommended maintenace. my son leaned into car, turned key (to lower windows), gear shift was in Park; it growled then jumped into the truck in front of it, damaged my car... any idea what the problem could be? anybody else have similar problem?
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