Lexus RX 400h and 450h

gagrice

Let me see if I understand. If you do a lot of coasting and running on batteries alone to get better mileage, you may be compromising the emissions system? Until the engine heats up to operating temp the catalytic convertor is not doing it's job. In the case of a plugin hybrid where you seldom use the ICE you may for those periods that it is used be polluting more than a normal ICE vehicle?

wwest

This explains why the ICE in the RX400h runs at unexpected times.

The ICE is run at times only to keep the catalyst fired off when it isn't really needed otherwise. Obviously it can/may still be used "otherwise" at the same time but the ECU probably mades the decision to fire up the ICE based on the need to keep the catalyst up to or near the optimum temperature.

Otherwise the vehicle would never pass emissions, certainly not at the ultra-low level.

otis1

I apologize if I start to go a little off topic here, but why is the catalytic converter "away" from the engine? I know there are smarter people out there than me who design engines. But if you look at this from a thermodynamic pov, the reason a gas engine is so innefficient is because of all the lost work from the heat that's generated (right?). yet it seems odd that you need to supply heat to a catalytic converter to make it work properly. Instead of using a heat-exchanger with the ambient air (radiator), why not do the heat exchange with the catalytic converter? I don't know, have the cat buried in the engine block or something. theoretically, if you capture some of this heat, you don't need to generate additional heat to warm up the cat.

wwest

Some catalytic converters are "close" coupled, such as was my Pinto station wagon's 2.3L I4. Mounted, coupled, right up to the engine manifold itself. I suspect it needed to be close coupled in order to get enough heat from the smallish I4.

If you have a look at the engine in question you will see why this is not possible with the RX400h. The exhaust stack comes off the manifold at the front side of the engine next radiator so the only "easy" placement of a converter is somewhat downstream of the engine compartment.

I also suspect that close coupling only works with smaller engines as a larger engine might result in overheating the catalyst if it were close coupled.

Apparently the "cat" needs to be in the range of 700F for optimum operation, given that the engine, coolant, and radiator temperatures never exceed ~180F you would need a heat pump cycle to raise those temperatures to the 700F required.

otis1

I'm not saying do a heat transfer between the water and the cat (where the temp will never reach 180), I'm saying do a heat transfer between the engine and the cat. (the engine has to be burning higher than 700F right?)

either way, I understand there may be a lot of reasons why this isn't feasible such as the space, cost, etc.... something like I'm saying may require big $$ to redesign a combustion engine- assuming the theory is even valid. I can see the cost benefit of using off-the-shelf parts such as the current 3.3 v6 with minor modifications.

peralta

"The ICE is run at times only to keep the catalyst fired off when it isn't really needed otherwise."

Compared to nonhybrid, that may not be the case.

On a hybrid, if it fires up to heat the cat, it also recharges the battery at the same time. Energy is not completely wasted.

On a nonhybrid, the engine is always running even if the cat is already hot, so there is wasted enregy when the vehicle is stationary.

stevedebi

"I apologize if I start to go a little off topic here, but why is the catalytic converter "away" from the engine?"

I don't know, a bunch of Honda CR-Vs caught fire because the oil filter was directly over the emissions system. The problem was a bad gasket, but having the hot catalytic converter right next to the exhaust manifold was a contributing factor, in my opinion. Of course, they could have put the oil filter somewhere else as well...

wwest

It's highly unlikely that any engine part gets much hotter than the coolant. The inside of the cylinder bore is continuously lubricated and cooled by the engine oil while the outside of the bore, ~1/4" away, is continuously exposed to flowing coolant.

Maybe the exhaust valve and its seat but there again the coolant is flowing through the head very nearby.

wwest

I thought I had covered that point implicitly, but.....

There will be times that the batteries are fully charged and thye vehicle is motionless werein the ICE will be fired up ONLY to lit the catalyst. But yes, certainly, if the battery needs to be charged and/or the vehicle is in motion then firing up the ICE will serve multiple functions.

The patent I linked appeared to monitor the catalyst temperature in order to determine when the ICE was to be fired up.

Several posters have asked why the RX400h's ICE runs so much/soon/often, seemingly needlessly, and the point I'm trying to make is to explain why that might be. Not contrasting anything with/about non-hybrids.

otis1

"It's highly unlikely that any engine part gets much hotter than the coolant."

just because the engine and coolant are at "steady state" doesn't mean they are at the same temperature. you can pour hot 100F water over an ice cube and cube will still be 32F while the water is still 99 or whatever. the temp change is a function of flow (among other things). just think if your water pump broke- the water "touching" the block would just boil.

I don't mean to get side tracked like this. I think the patent was interesting (at least as interesting as a patent can get). It just seemed strange that you would need external heating (prior art) or a sensor to switch on the ICE (patented claim) when there appears to be a good heat source available.

maybe I should file a patent :P

wwest

I didn't mean to imply that they would be at the same temperature. I wouldn't hazard even a close guess what the engine components might be. But I would bet none of them are anywhere close to the point wherein their HEAT can be used to keep the catalyst up to the required 700F temperature.

fizban

Also note that this patent is 2 years old. I'm wondering what in-roads have been made since May of 2002.

dylan hixon

Catayst light-off has become one of the major issues for automotive emissions. As engines get cleaner, and catalysts more efficient, the little window of time at the begining of the FTP (federal test procedure) where the engine is cold started and the catalyst is not effective, actually produces most of the pollution for that portion of the test. Extensive work was done on electrically heated catalysts, but I don't think they have ever been used commercially. The best solution, other than a close coupled catalyst which is usually impractical, is mini-cats, which are small, close coupled catalysts in the exhaust manifold which light-off quickly and heat the main catalyst, and double walled manifolds, et cetera.

Also, don't confuse operating temp with light-off temp. Lightoff temp is the point at which self sustaining reactions begin, and those reactions quickly heat the catalyst to its operating, which is hotter than the exhaust. Light-off is about 300-500F (depending on age), and operating temperature can be up to red hot, but depends on how much fuel is in the exhaust.

When the hybrid runs it's engine to heat up the catalyst, it does so with a retarded spark timing to get the exhaust temp as high as possible with no load, and it almost always charges the battery at the same time, since the battery is almost never full. However, I have been sitting in my car with the engine running but nothing on the energy display. I have to assume that is heating only.

I bet this is a devil of a problem for a hybrid trying to get a SULEV emmissions rating on a city cycle with the engine starting and stoping all the time, and the catalyst cooling down.

wwest

Which is why the RX400h doesn't have the far more fuel efficient Atkinson cycle engine.

Pardon me while I step outside and check to see if the Prius' catalyst is "close coupled".

wwest

But my 30 minute edit window had expired....

So, I'm back, but feeling a bit stupid.

Visually I learned that the intake side of the Prius engine is in front which would allow for close coupling. As I stood there trying to figure out how to actually get under the car and look it came to me that I had a complete set of Toyota shop manuals for the Prius.

The Prius seems to have three catalyst containers and a muffler in the exhaust stream. The first catalyst is DEFINITELY close coupled, bolted right to the engine exhaust manifold. One oxygen sensor right at the exhaust manifold and one after the close coupled catalyst.

What is interesting is that the Prius has a vacuum driven servomotor that operates a bypass valve just downstream of the first catalytic converter, after the second oxygen sensor. With a "cold" engine start the bypass valve closes (partially??) the exhaust outlet from the first converter until the "HC absorber's" temperature is raised to the proper operating level.

Apparently it also closes the bypass valve during decel or idle even if the catalyst temperature is already high enough "in order to scavenge the HC that remains in the absorber material".

Wonder what the service life of a bypass valve operating within the exhaust system might be?

skyfish400h

This may be premature, but how in the world are they going to smog these vehicles in CA?

They can't use the rollers since it is an AWD.

They can't just use the tail pipe sniffer since there is no way to directly control the ICE RPM, or for that matter even control when the ICE is running.

Are we exempt or what?

wwest

and their little black box design.

If you do some research here and there on the internet you will find that the emissions stations will be able to connect directly into your engine's control ECU via your standard diagnostic plug and determine if all of the smog control devices and sensors have previously and still are operating within the correct parameters.

Basically CARB has stuck a deal with the auto industry wherein your emissions content is being continuously monitored as you drive. Unplugging the battery prior to driving up to the emissions station will result in a "hell I don't know, I'm brain dead" message from the ECU and then you will be required to go through a fairly complex drive cycle ( low speed, stop and go, highway cruise, etc, etc.) before returning for the emissions check.

rxcure

I'm close to buying a 400h -- cool technology, sends a message to car companies that we want more choices, great performance, nice luxury, etc.

BUT, as with any new technology there are likely to be bugs. Last thing I want is to have spent the extra money on this (rather than 330), and then get into my car in the airport parking garage after returning from a trip and find that my cool new car won't start. Any perspectives on the reliability of these vehicles? Having owned one for a month or so are you still happy w/ your decision?

Welcome any thoughts!

wwest

now has ~17,000 trouble free miles.

While the RX330 has some sort of engine hesitation problem that Toyota, seemingly, refuses to address.

love2scuba

I would do it again in a heartbeat. Mine has been in the shop once for a bad hard drive that controls the GPS system. Can't really blame Lexus too much for that one, it happens, but the quality of the GPS drive they picked could have been better. Mine was the second 400h in that week for the same problem. I have almost 4,000 miles on mine have owned it since 4/18. Overall, I'm a very happy 400h owner.

maxamigo

Wwest,

You bought a 2003 Prius and only have 17k miles ?????

I do 30k-35k miles a year... so it pays off faster.

mzuckerman

I've had ours for one month, now has 3000 miles, zero problems, avg mpg 25 in half city half highway driving with AC on full blast.

wwest

My grandchildren will have clear air to breath and hopefully delay global warming for a few thousand years.

rxcure

There's always a vocal few who speak up with problems on their vehicle. So the lack of any negative posts today in response to my question about problems combined with a call from the sales manager means I worked out a deal and will pick it up tomorrow ... joining the future with a new hybrid!

love2scuba

Congratulations! You will love it. Just wondering if you were you able to get it under MSRP? Thanks!

rx400_owner

One exception is maybe put a low rolling resistance tires to RX400H, while sacrificng traction and ride comfort.

More than ride comfort, I thought the issue is that sacrificing the traction would sacrifice safety, especially given the weight and torque in this vehicle. I wouldn't want to try that mod.

Other than that I agree with you.

wwest

I have Bridgestone Turanza ER30s on my AWD RX300 and should I buy an RX400h they will be transferred. Snowchains will always be my choice for "high traction".

rxcure

Paying MSRP and got what I believe is pretty good value on my trade so pretty much an MSRP deal w/ no hidden premium. Waiting list length seems to vary widely by dealers. Potential buyers should choose a dealer in a less populated area and/or a newer dealer and you may find they are happy to talk. The well-established dealer in my area basically said take a number and we'll talk next year whereas a new dealer had one available now.

ultra64

Dealers in my area will go about $2000 under list for one they have in stock.

babysnow

what area are you in?

rxcure

Massachusetts ... I see you are in LA and would imagine these are in pretty short supply. You could always look for a dealer far away and either fly there & pick it up, or have it shipped. I remember when the Acura MDX was new and hot that some people resorted to that. For a car in this price range you could easily find a better deal that makes it worth the hassle. (need to check in advance how to sort out the registration, for example)

ultra64

DFW. I got a nice quote from one dealer that mine improved a bit by doing like they say here -ask for a price quote via Edmunds.com. I was surprised that they discounted the 400 but some dealers have more 06' 400's than 05' 330's on their lots.

horns1976

I got an email quote from dealer in Louisiana...$1500-$2000 off sticker...without asking for discount. Dealer in Texas (where I live) quoted $883 discount without being asked for discount. My opinion, for what it's worth, is that if you can wait a month or so, dealers may be more motivated to deal. But, that's just my opinion.

hybrat

Am I the only Canadian here ... eh?

Anyway ... I found a good site to do metric conversions
link title
so you can compare Canadian apples to American ones. It can get a bit confusing when you grew up with and still think in mpg (Imp.), much of the discussion on these forums is in mpg (US), and your car is calibrated to L/100 km.

Since the denominator is inverted in the L/100 km gauges, seeing the bars go up or across in the mileage meters is a bad thing. At a standstill, mpg is zero whereas L/100 km is infinite. I hope this is accounted for in the average consumption calculations!

I have noticed when the ICE initially fires up the consumption goes through the roof. Perhaps this improves once the engine is broken in. I've had her for a week or so and like eman5 above me, I notice the car seems to sometimes pull to the side. Is this a foible of electric steering? My consumption is also about the same but based on earlier discussions I am expecting it to improve.

Apart from that, I am loving this car!

skyfish400h

I've experienced the effect some have describe as well. Being kinda finicky about that with my Supra, I've taken it back to the shop (where I have the lifetime alignment deal) and asked them to "tune" my alignment within the manufacturers tolerances and I can tell the difference.

What is probablby happening is that the factroy settings are broard enough to allow for a pretty wide range of "feel". At least in my opinon... most people probably would never notice.

The thing to do is have the dealer check the CASTOR angle and verify that it is at the HIGH end of the range. This will give the steering a heavier feel and it will tend to want to center better rather than following all the little grooves and slopes in the roadway.

The other thing that will affect this is the TOE IN value. If it is on the LOW end of the tolerance you will tend to wander more. All cars will have some toe in to make it more stable, but you will pay the price in fuel econnomy and tire wear if it is excessive. I like to keep my CASTOR - HIGH and the TOW IN - LOW to balance stability and road feel against tire wear and fuel consumption.

hybrat

I took my 400h to the dealer today to have the alignment issue investigated. Of course I offered my edmunds forum derived theory that the car perhaps was aligned to 330 specs? When I picked up the car here's what the warranty repair invoice said:

"CONDITION: STEERING FEELS UNSTABLE WHILE DRIVING

CAUSE: WHEEL ALIGNMENT OUT OF SPEC

CORRECTION: COMPLETED 4 WHEEL ALIGNMENT"

I am happy to report that my 400h now tracks like a luxury SUV oughta. Much much much better!

hybrat

So my BMW (the 400h is my wife's car ) also has an accumulated gas consumption meter. It is telling that in the four years that I've I owned the car I haven't paid any attention to it.

The BMW is rated 20 mpg US city and 27 mpg US hwy. I decided to run them both on a comparison test in what worked out to be an 18 mile (29 km) loop through the city and took accumulated mileage readings at various check-points along the way. I drove both vehicles normally (no jackrabbit or granny starts), staying within 10% of the posted speed limit. It was early evening, no wind, dry roads, temperature 68 F (20 C), A/C was on in both cars (but obviously not taxed), traffic was light, and both cars had not been driven for at least three hours.

Checkpoint 1 was almost a mile (1.4 km), then a freeway drive at speeds of approximately 70 mph to downtown to Checkpoint 2 at 7.5 miles (12 km). Checkpoint 3 was a cross town drive to a residential area at 10.5 mi (16.8 km). Checkpoint 4 was a nice drive by the river to 13 mi. (20.7 km). Checkpoint 5 was to home again through typical city streets (lots of traffic lights, heavier traffic) and some freeway.

The results are telling I think (results are in US mpg (L/100 km))

(mi) BMW // 400h

#1 (1) 16.2 (14.5) // 14.4 (16.3)

#2 (8) 26.0 (9.0) // 24.0 (9.7)

#3 (11) 24.5 (9.6) // 25.8 (9.1)

#4 (13) 24.8 (9.5) // 28.7 (8.2)

#5 (18) 23.2 (10.1)// 29.0 (8.1)

Evidently, it is the short cold engine trips that accumulate to make for a poor showing in mileage about which some owners are complaining. This is the same for any car but seems to be worse in a hybrid. However, the engine in my 400h has only 250 miles (400 km) on it. I intend to run the same test in a month or so after the engine is well broken in to see if it matches up better with the BMW on the first legs of the test.

Kirstie_H

A reporter is hoping to talk with someone who purchased a European, Japanese or Korean crossover vehicle since January 2005. Please respond to jfallon@edmunds.com before July 2, 2005 with your daytime contact info, the make and model of your crossover and a few words describing why you chose it.

rx400_owner

Nice work hybrat and I'm glad to hear your steering issues were resolved.

The numbers illustrate nicely why I think Canada has the right idea when it shows mileage as a volume over distance measurement instead of the distance over volume the US uses. Most of us have a given distance to drive and it gives a more accurate picture of the effect of the number on our wallets.

For example: 14.4 to 25.8 mpg with an improvement of 10.4 mpg saves 7.2 liters of gas over 100 km of driving.

going from 25.8 mpg to 29 mpg, another 4.2 mpg improvement saves only 1.6 liters.

even if you went from 25.8 to 36.2 you would drop liters/100 km from 9.1 to 6.5 so you would save 2.6 liters. The mpg improvement looks large, but we get diminishing returns in savings per distance driven when it looks like the mpg number is soaring up.

That also helps explain why seemingly small factors like the AC running make a big difference to the mpg reading on the more efficient cars. Relatively small changes in gas consumption make bigger changes in the mpg rating for high mpg cars.

I wonder why the BMW does so much better on the cold engine than the hybrid.

horns1976

I just want to report that the 400h that my brother purchased on 7/1 pulls to the right as described here. In some cases, it pulls hard right. A friend of ours was driving the vehicle today. He drives for a living. I asked him if he noticed that the car pulls right so I could verify my observation. He said he agreed that it pulls right. So, that will be job one for the dealer to investigate.

wwest

With the "old" way, hydraulics, the power stearing pump is always turning and generating fluid under pressure, if the volume pumped each revolution is not "used" (and mostly it isn't!) it is bypassed back into the sump, total waste of energy....

Well, not quite.

Since the pressure (~1000PSI??) is always there and readily available it is ALWAYS used to help keep the front wheels pointed in the direction you designate with the stearing wheel with a very high degree of resolution and POWER.

In the RX400h using the same level of ELECTRIC power to keep the front wheels "on center" would result in a complete discharge of the hybrid batteries in very short order.

So if you're coming from a car using the "old way", to an RX400h, you will feel as if the front wheels are more easily drifting from "on center" simply because they are!

rain39

My rx400 now has 2500 miles on it. I am only averaging 21 on the road and 22 in town. I drive conservatively and am getting pretty frustrated. Live in Texas so the AC is definitely on. It is surprising to me that there is such a small spread between in town and highway driving. Is anyone else experiencing this? Thanx

cyclone4

"Something is rotten in the State of Texas", rain39! Seriously, there is no way you should be getting that poor of a gas mileage. Take the 400h to the dealer immediately to have it checked out and explain to them that you are not driving like a maniac and that the gas mileage should be a lot better. Something is wrong.

If you drive conservatively, you should get close to the EPA stated 31 mpg in pure city driving without the AC on & perhaps 29 with it on. I would say that with the AC on, you should be getting about 24-25 on the highway.

rx400_owner

wwest, My Rx 400H steering feels quite steady - at least as good as with my Camry. I'm definately not experiencing the pulling that some others have complained about. On top of that, hybrat and some others who have reported the problem have had it fixed by alignment. Hybrat posted some information on what they did in the 400H to get good handling.

Poor steering shouldn't be settled for. The 400H being delivered with a poor alignment seems to be a wide-spread problem (from this and other boards) perhaps because of confusion on what the correct settings are.

rx400_owner

I agree that rain39 should be seeing better mileage than 22/21 even with AC. However, a heavy AC load has a much bigger effect on city mpg than on highway (and gives a good example of why city mileage in general is more variable than highway). Here are some back of the envelope calculations to explain.

On triple digit days (>99 degrees F), I see highway mileage drop about 2 mpg from 27 mpg to 25 mpg. I see that pretty repeatably. Here's how much fuel I'm using for an hour of driving:
no AC 27 mpg 2.4 gal/hour
with AC 25 mpg 2.6 gal/hour
So cooling is costing me about 0.19 gal/hour (I'm pulling numbers off the spread sheet and not putting in all the digits which is why the number is .19 rather than .2)

City driving should require about the same amount of energy to cool the car per hour but the average speed of the car is much lower. The EPA city profile average speed is 20 mph. At 31 mpg, an hour of 20 mph average speed driving uses 0.65 gallons of gas. If AC still adds 0.19 to the gass consumption, an hour of 20 mph driving with AC on requires 0.84 gallons of gas. 20 miles/ 0.84 gallons = ~24 mpg.

The AC load that pushes highway mileage from 27 mpg to 25 mpg could push city mileage from 31 mpg to 24 mpg.

My city mileage is more suburban than city so it is a good bit higher speed so the mpg penalty I get isn't quite as bad as that. On the recent triple digit days we are having I'm seeing 25 mpg city and 25 mpg highway.

The current heavy AC load also really pushes up the short trip penalty too. Get in a hot car and the AC has to blast for the first 5 to 10 minutes.

gagrice

heavy AC load has a much bigger effect on city mpg than on highway

Here is another thought. Two of the three RH owners reporting very low mileage 19-22 MPG, are in very hot 100 degree plus areas of TX and CA desert. Maybe the electric motor generators are more stressed at the higher temperatures. That was the reason for not using the RX400h offroad. It would overheat the rear drive electric motor. Heat is not good for any electrical/electronic device. Maybe Toyota has used air conditioning to cool the battery and other critical electronic modules. That would keep the AC running even more. I noticed on the GMC mild hybrid that when I am at a stop light the engine shuts down for the whole time. If it is very warm and the AC is high the engine starts up before I take my foot off the brake. Presumably to keep the batteries at a proper level.

wwest

How about the fact that the engine coolant is also pumped via ELECTRIC?

In a HOT climate where A/C is used constantly it's also likely that the engine coolant pump motor is drawing a heavier load...

Haven't I read that there is a C-best option for the Prius wherein the A/C reheat/remix method is "short-circuited" in favor of just refrigerant cooling?

If that option is available for the RX400h the owners might consider having it enabled. That would likely result in less runtime for the engine and certainly less use of the engine coolant circulation pump.

wwest

Has anyone thought seriously about a small highly efficient APU in a hybrid to power all of the accessories?

Maybe its exhaust outlet could even be used to keep the catalyst "fired off".

rx400_owner

The weather the last few days here has been near or over 100 degrees F. I'm still making 25 mpg and that includes some short errand trips. I'm not experiencing what you describe in terms of ICE cycling.

When I first start out, the AC is running nearly continuously as one would expect with a very hot interior needing to be cooled. Even with that, the engine still shuts down the whole time when I am at a stop light or sign. The difference I notice is for the first few minutes of driving any application of the accelerator turns on the ICE - even just puttering through the parking lot. After the first few minutes when the car has gotten to a reasonable passenger compartment temperature, the AC settles down and the motor versus engine usage becomes similar to what happens in cooler weather.

I don't see any sign that the AC is being used beyond a normal amount. It is just hot weather and the AC takes some energy to run.

cyclone4

I cannot argue with anything you state. You are probably correct. I have not done enough testing with the AC on in real hot conditions in the city.