wwest

Cats glow with engine revving..... Catalytic converters do not glow in the short term, do you really mean Cats as in catalytic converter? If you have already changed the catalytic converters then did you check for blockage downstream in the exhaust pipe? I have seen "cats" glow but only after long term use of the engine and that was the result of chunks of the catalyst honeycomb structure breaking off and blocking the exhaust flow. The only other reason that comes to mind is an extremely RICH mixture, or unburned fuel reaching the catalyst. And I don't see MAF, mass airflow sensor on your list...maybe....

Why not just assume I'm a jerk and don't read my posts. That's okay by me.

My own experience is that at sub-freezing temperatures freshly falling, fallen snow has about the same traction coefficient as beach sand...

Back in 1963 in MT I truly loved driving around after a freshly fallen snow and blasting through those high snowdrifts in my new T-bird. The only shortcoming was that once in awhile the radiator would get clogged, PLUGGED, with snow and then I would have to get out and clean it out. Once in awhile I would get high-centered since the bottom of the T-bird acted like a sled, but hey, what's a little honest fun without retribution. But when the stuff that drifted got packed down I had to get serious and put the chains on.

The AWD system on the RX does have many limitations as has been discussed here many times. But performance in light to moderate snow is one of its stronger points. I suspect black ice or mediocre tires as lexus411 did. Please keep in mind that most winter type tires are like, equivalent too, those huge MUDDERS you often see on off-road vehicles. If there is no "loose" surface layer for the tread block to "bite", sink into, they will provide less overall traction than your standard "summer" tire simply because they have less surface area for contacting the roadbed. And now someone will bring up that "old saw" about winter tire tread rubber compounds being more compliant with COLD roadbed surfaces. The bottom line is that every demostration of winter tires' traction I have ever been aware of, seen, involved a good top layer of loose snow. Show me a comparison test of winter tires vs summer tires on an ice rink and then I will believe. Meanwhile I'll continue running my Bridgestone Turanza SUMMER ONLY tires for their comfort and quietness and resort to tire chains when the need arises, which is RARELY. Winter tires are definetly better on ice. You may want to check out some of the tests at tire rack. It looks like excatly the test you are requesting. They have been testing tires on a hockey rink for the last 7 years. When was the last time you saw TireRack test a summer tire against what they want to sell you as a winter tire, hockey rink or not?

Nor is the RX a capable transport during an ice storm, or on any icy or highly slippery surface. But then absent studs or chains neither is any other road going passenger vehicle that I know of.

"...driving around in 4" of snow......" The operative term there is driving around "IN" 4" of snow, not driving around "ON" 4" of snow.... Not even most 2WD vehicles would be challenged driving around IN 4" of snow. But pack that same 4" down so you're driving around ON 4" of snow and it would be a totally different story. Tell you what, I'll go and have my 2001 "AWD" RX300 converted to solid RWD coupling with the VC as backup to couple in the front. Then I'll race you anywhere any distance of your choice with you driving ANY model year AWD RX series as factory delivered. The factory supplied RX series is AWD in name ONLY.

Wasn't much choice back in my time, either RWD (maybe w/LSD) or Dodge 4X4 Power wagons. I guess the rental companies didn't cotton much to stocking power wagons throughout the year.

The AWD system on the RX does have many limitations as has been discussed here many times. But performance in light to moderate snow is one of its stronger points. I suspect black ice or mediocre tires as lexus411 did. Please keep in mind that most winter type tires are like, equivalent too, those huge MUDDERS you often see on off-road vehicles. If there is no "loose" surface layer for the tread block to "bite", sink into, they will provide less overall traction than your standard "summer" tire simply because they have less surface area for contacting the roadbed. And now someone will bring up that "old saw" about winter tire tread rubber compounds being more compliant with COLD roadbed surfaces. The bottom line is that every demostration of winter tires' traction I have ever been aware of, seen, involved a good top layer of loose snow. Show me a comparison test of winter tires vs summer tires on an ice rink and then I will believe. Meanwhile I'll continue running my Bridgestone Turanza SUMMER ONLY tires for their comfort and quietness and resort to tire chains when the need arises, which is RARELY.

In general once you're up and going at some speed the vehicle's inertia, momentum, is the ruling factor. As has been said so many times before, the only advantage to additional "DRIVE" traction, more tires being driven by the engine, is primarily for acceleration. In comparison once you are up to speed the level of traction needed is only that required to overcome the various sources of drag. "....Fresh 10" powder on the roads after a heavy snow..." First, can you send some of that "powder" down our way? All we seem to get is the heavy wet stuff referred to as Pacific boiler-plate. Years ago in the wintertime in MT, 1960s, mostly RWD, I would have welcomed 10" of fresh powder instead of the icy stuff that had already been packed down from being driven on. During my time in Alaska, Anchorage, Fairbanks and Barrow, I most feared the glare ice that seemed to persist for months in the wintertime. Now that stuff can be treachorous even with a 4X4. But those RWD rental cars seemed to get me around just fine until the spring thaw.

You need to keep in mind that your previous FWD had a very low margin of extra traction. If you did not have traction control and tried to accelerate in those conditions you very quickly learned the traction limits due to uncontrolled wheelspin. You learned not to use too much "leadfoot" than was warranted by road conditions. With a FWD vehicle and a slippery roadbed you can always accelerate at a faster rate going straight ahead than you can during a turn. If you did have traction control then the "learning" process would be even quicker. At the instant wheelspin developed the front brake(s) would be applied, possibly moderately, while at the same time the engine would be dethrottled. So now you, by default, learn at what level you can use the accelerator pedal without the traction system activating and assuming control. Since an AWD system gives you more leeway, a greater level of overall traction for acceleration on a slippery surface, the traction control system will be somewhat "detuned", less sensitive to quick activation in the case of wheelspin. You said that as you accelerated into a turn the rear end started to come about/around. The proper reaction for you, as the driver, at that point in time was to lift the throttle and stear into the skid (opposite the direction you initially turned). Absent doing that fairly quickly the VSC will activate, dethrottle the engine and apply braking to the front outside (outside your initial turn direction) wheel to provide "moment" to bring the rear back into line. I don't know, can't say, about the Lexus VSC/Tarc system, but the activation of PSM in my Porsche (equivalent to VSC/trac) is intentionally delayed so as to give the driver time to react on his/her own. In the end that would be the most reasonable method of implementing these functions since that way there would be less chance for inadvertently "doubling" (simultaneous driver and ...) the corrective measures for understearing, over-stearing, or loss of traction due to "leadfooting".

No, I think this discussion is about, centers around, the Lexus RX series having, or not, the same AWD capability as the Jeep. So we are disregarding the 4X4 (locked center differential) mode and the granny-grunt "low" 4X4 mode, in this comparison. Personally I don't think it's at all wrong for a person purchasing an RX to expect AWD system performance equal to the equivalent mode available in a Jeep. To clarify, the 85 and 92 Jeeps I had could be switched from RWD to AWD to 4X4 (locked center diff'l) and then into 4X4 low range.

Jeep vs RX comparisons... NOT! I think we were comparing the two in relation to our own personal useage, not the extended functionality of the Jeep. I suspect that the clear majority of Jeeps purchased are used in exactly the same way as do RX purchasers. Basically we purchase because we need AWD functionality as an exception, not as a rule. The difference is that the Jeep has a long and illustrious history as being world renowned in the area of exceptions, encountering adverse roadbed conditions, simply becuase we all know it also does extremely well in off-road conditions. But with an RX purchase you don't discover how poorly the AWD implemention is until you inadvertently encounter your first EXCEPTION. Think about this, if, as in the RX330 series, wheel braking is used to apportion engine torque, how will the new RDX350's VC work if Trac is still used to apportion engine torque? I'm fairly confident that the reason the VC was abandoned in 2004 was because the Trac system even in my 2001 made it useless. The VC cannot stiffen up and lock, partially, the center differential absent disparate front to rear drive line rotational rates. If, on the RX350, Trac is used throughout, as it is on the previous models, all four wheels, how does disparate rotational rates ever become an issue?

In actuality both vehicles, FWD and AWD, may have the exact same ECU and firmware. With FWD the rear wheels will NEVER develop wheelspin/slip due to engine torque so that AWD "section" of the Trac firmware will never execute. Otherwise the only real difference being the mechanical aspects, the center differential, PTO, rear driveline, etc, and the VC to hopefully stiffen up if front wheelspin develops. But then of what use is the VC if Trac is used to simulate a front LSD?

All of the testing I decribed was with the 2001 AWD RX300 and was within the first 6 months of having purchased it.

It might have to do with the initial level of charge in the hybrid battery when you first begin braking. If the level is close to the "top" then a low priority is given to regenerative braking in the firmware decision "tree". The system ECU is "watching" your braking and acclerator pedal activity, continuously, in order to be able, a majority of the time (hopefully), just what your "intent" is. It's tryingto predict the future, literally. For instance if you have been cruising along at a relatively constant speed and then suddenly lift the accelerator pedal the system would likely conclude that you intend to begin coasting down to a lower speed. Now if you suddenly, immediately after releasing the accelerator, apply the brakes the system will probably assume you want to slow down quickly and the brakes are the proper resource for that. On the other hand suppose you were just previously accelerating and now only slightly release the gas pedal. The system would properly assume you want to enter cruise "mode". In your case when you first, initially, applied the brakes the system could have been indecisive about your intent. But then you released the brakes and then re-applied them (non-severe assumption here) and that would clearly imply a non-urgent coastdown and then it would be appropriate to engage the regeneration cycle. If the hybrid battery were nearly discharged I have no doubt that regeneration would have begun the instant you released the accelerator, even before you applied braking the first time. Like the Sargeant said on Forest Gump: WWEST, you are a $@%# genius!! Thanks for the excellent explanation of how the 400h computer makes its decisions!! The upshot is that I should take my foot off the gas first, wait a second and then apply the brakes. Was I, or was I not, just compared to Forrest Gump..??

Weird, WEIRD... It turns out I am the winning bidder on Ebay for a driver side mirror for an RX330. The text represented it as a D/S for the 2001 which is why I bid. Item # 8040551804 If it will work for you make me an offer above $100.00

It might have to do with the initial level of charge in the hybrid battery when you first begin braking. If the level is close to the "top" then a low priority is given to regenerative braking in the firmware decision "tree". The system ECU is "watching" your braking and acclerator pedal activity, continuously, in order to be able, a majority of the time (hopefully), just what your "intent" is. It's tryingto predict the future, literally. For instance if you have been cruising along at a relatively constant speed and then suddenly lift the accelerator pedal the system would likely conclude that you intend to begin coasting down to a lower speed. Now if you suddenly, immediately after releasing the accelerator, apply the brakes the system will probably assume you want to slow down quickly and the brakes are the proper resource for that. On the other hand suppose you were just previously accelerating and now only slightly release the gas pedal. The system would properly assume you want to enter cruise "mode". In your case when you first, initially, applied the brakes the system could have been indecisive about your intent. But then you released the brakes and then re-applied them (non-severe assumption here) and that would clearly imply a non-urgent coastdown and then it would be appropriate to engage the regeneration cycle. If the hybrid battery were nearly discharged I have no doubt that regeneration would have begun the instant you released the accelerator, even before you applied braking the first time.

A good indication of the lack of AWD capability of the entire RX (and HL) series is the fact that the factory recommends that tire chains be used ONLY on the front wheels. In point of fact tire chains cannot be used on the rear due to poor tire and suspension element clearances. Anyone who will willingly drive ANY vehicle with tire chains only on the front in truly adverse conditions for any distance other than a long driveway must have a death wish. Right in your own owners manual it states that an inordinate level of traction at the front versus the rear can too easily lead to loss of control. Keep in mind that a FWD vehicle with the engine at the front already has more traction at the front vs the rear so it doesn't take adding very much to become unsafe. This statement is made in regards to having winter tires on the front and not the rear but then with a page or two all that is forgotten so they can tell you to use tire chains ONLY on the FRONT. I could forgive them that provided a note of caution followed stating that maximum speeds with only front tire chains should be limited to no more than 10 MPH or 5 MPH downhill. I put 1.5" wheel spacers all around on my 2001 AWD RX300 to provide the clearance necessary for rear tire chains and I carry two sets of chains during the winter months, first on the rear and then the front if needed. And yes, on an RX the rear chains provide more "drag" than drive but that is what is often needed most on really slippery surfaces. The spacers also allowed me to upgrade to 17X8" wheels and wider summer only Bridgestone Turanza tires. 3" wider stance results in more stability against rollover and the wider tread yeilds more overall traction. I run summer tires all year around for comfort and quietness and simply throw on the tire chains for the few times they are needed here in the Seattle area. From time to time I have considered modifying, eliminating, the center differential functionality in favor of a SOLID coupling to the rear and thereby allowing the VC to provide the only front drive torque. For that reason I was somewhat enthusiastic about the newly available RX350 again having a VC, but I want to wait until I can see and test drive the new Acura RDX first before I make that decision. By-the-by, it's pretty obvious that Toyota has begun to recognize that FWD and front biased AWD vehicles are inherently unsafe, probably even hazardous for adverse roadbed conditions. For proof just read up on how the new Lexus IS & GS AWD systems dynamically allocate engine torque according to signals from the VSC's yaw sensor. The documentation on the 4runner isn't as clear, explicit, but the same AWD system firmware seems to have been carried over to it. The AWD systems in the Volvo XC90, Ford FreeStyle, and now even the Acura RDX are also good examples of how the world is chainging with regards to the poor safety record of FWD. Rear torque biasing in a Volvo? For an Acura? Not possible.

I was by no means using the gasoline boiling to explain how an air bubble got into the engine coolant system, I thought that had been well covered already. I have overhauled not just a few engines in my lifetime and was always careful to monitor the cooling system for inadvertant "vapor locks", coolant voids, after I put things back together and then refilled the cooling system. "...it took several days...." "...which is normal..." ??? Absolutely not! If you are hearing bubbling sounds in the coolant flow that means that you're still pumping air along with coolant. In that case there is a significant danger that a large air bubble will become "lodged", say within a cylinder head, and now you can end up with really serious problems. And by the way, fuel pumps for diesel engines run an extremely high pressure level, so yes, vapor lock, when and if it happens, is a relative short term thing. On the other hand fuel pumps to fill a carburator fuel bowl ran/run at what, 2 or 3 PSI ??

Been there, done that. I traded up from a MY2000 AWD RX300 to a MY2001 AWD RX300 mostly to get the HID headlamps and the new VSC/Trac system. I had begun to suspect that my 2000 wasn't really AWD and this had been verified partially by Lexus informing me that it was fornt biased 70/30. I'm old enough that my color night vision is fading and the HID does help. I was told that the rear LSD option had been dropped in favor of brake apportioning being used to prevent wheelslip/spin in the front or the rear, "virtual" LSDs in effect. That turned out to be true and I suspect that also works front to rear even on my 2001. By happenstance I ended up driving down a very wet and muddy lane to a friend's house and when I tried out the AWD by trying to accelerate I didn't get the same "feel" of AWD an I had in my previous two Jeeps, and 85 and a 92, both with 2WD, AWD(??), & 4X4. 4X4 low also which I never used. So I came home and put the RX up on four jackstands and discovered that there was virtually no drive to the rear wheels. To verify that I placed a 1x2 light pine board through each the rear wheels to prevent them front turning, safely. Then I started the RX, put it in drive and was able to raise the engine RPM substantially, 2500 RPM I think I remember, with the 1x2 only making creaking sound and the front wheels turning cogizant with the engine speed. Next I did the same thing in reverse, 1x2's blocking the front wheels. I no more than raised the throttle above idle when both 1x2's snapped. I published these findings on the internet and got lots of naysayers disputing my testing procedure so I took the RX to nearby Redmond and had the testing done on a four wheel dynamometer. The results were the same, using the rear dyno to brake the rear wheels the engine seemed totally free to drive the front wheels alone. The rear dyno braking had so little effect on engine loading the HP/torque delivered to the rear could not be measured. It ended up taking a matter of tens of seconds before the viscous fluid heated up enough to couple even ~25% of the engine torque to the rear wheels. As likely most of you know the VC was dropped entirely in 04 in favor of using only brake torque apportioning. The Trac system is used to apply braking to any wheel or wheels that slip/spin beyond the level of the current roadspeed determined by the speedometer or in the case of AWD wherein all 4 might spin simultaneously the accelerometer. Once the brakes are used in this manner if the condition persists then the engine will be dethrottled (fuel stavation prior to 04, DBW thereafter) to prevent the braking action from overheating the rotors. Since the ABS pumpmotor is relatively smallish, fractional HP, about the same as drive your windshield wipers, it would ordinarily overheat quickly so a 45 second timer limits the period of continuous or semi-continuous use of the RX330 series AWD system. So if you wish to use wheelspin, rocking back and forth to get unstuck you will need to disable the Trac system first. Simply unplug the MAF/IAT sensor module on the intake downstream of the air filter, let the engine die, plug it back in. You will get a CEL & VSC trouble light but now the Trac will not interfere with intentional wheelspin. The indications will extinguish after about 4 drive cycles. I notice that the new RX350 has the VC again but I haven't been able to find out anything about how it might interact, or not, with Trac. "The Relentless Pursuit of Perfection" RELENTLESS..............

The smalller the tube/pipe carrying the liquid, versus the liquid's viscosity, the more likely it is that once an air bubble is established, it will not move allong with the liquid flow but remain in the tube as a flow blockage and therefore whatever liquid continues to fluid mus flow around the perimeter of the bubble, resulting in highly restricted flow. It used to be that the most common occurance of this was in a gasoline line. In the south on an especially hot day the combination of natural heat plus that of the engine having just been shut down would result in boiling the gasoline inside the lines to the carburator. Bubbles in the line would result and when you next tried to start the car it would only idle due to the restricted flow. Given the relatively low viscosity of coolant the only pipes/tubes small enough to "hold" an air bubble in place and thereby restrict the flow would most likely be in the heater core.

If it looks heat cracked then there is a TSB to cover it. New mirror, heated and electrochromic dimming, $365...

I have always, religiously ( or so I thought) used my right foot for both braking and gas. Then last week I realized that the one time the firmware designers could likely rely on the gas pedal being at idle, and thereby reliably "learn" the gas pedal idle position, was during the sequence of firmly applying the brake in order to have the electric solenoid release the shifter so it can be moved out of park. So the issue is NOT what foot you use for braking otherwise, but specific to the exact time you are shifting out of park. After realizing the above I started paying more attention to my own driving methods. Low and behold it turned out that I had a habit of using my left foot on the brake each time I shifted out of park. For some reason I had developed the habit of applying the brake with my left foot in this instance circumstance. What was I doing with my right foot...? In the case of preparing to back out of my garage, and as it turns out any time I am backing up, my right foot is always on the accelerator pedal with my left foot applying or poised over the brake. Probably lucky that I don't have DBW.

"vapor-lock" an air bubble blocking flow, can occur in any liquid distribution system.