bwsteg

How many MPG were you averaging before the work was performed?

joejay

I was getting around 18 in the city and 22-23 on the highway. Recently I got 28 coming home from Santa Fe NM!

RX3302004

That MPG sounds awfully low to me.

MI SO FST

iTrader: (9)

Good morning guys,

I know this is a super old thread but I'm having these same problems. Is there any update on this? Did resetting the ECU work?

RedGemini

Same here. I know this is winter, and it's been pretty cold here, but I got 14.5 (calculated) from my last tank, and I don't usually let it warm up for too long - maybe 5 minutes at most, and that's only when the temps are below 20º. Typically I only allow it to warm up for about 30 seconds or so before driving. The best I've gotten so far was 22, and that was on a trip I typically refer to as "my ultimate gas mileage route" due to the combination of mountains (strange, I know, but you'd have to know the route), and speeds mostly under 60 MPH. Every vehicle I've used for that trip has blown past the EPA highway ratings, but my RX barely scratched it.

Yes, I have to check the air filter, and I'd like to change the spark plugs, but since I don't have a garage easily accessible for DIY jobs in this frigid climate, some works has to be put off. As stated above, I can't see how an air filter would cause such drastic results.

Fuelly decided to lose my first few entries, but here's the most recent 3.

LSBen

Remember to check your tire pressure when the temperature drops. You lose 1 psi for every 10 degree Fahrenheit drop in temperature. I was getting about 15% worse gas mileage until I added 5 lbs to each tire. Give it a try

RedGemini

I pulled the negative battery terminal for 2 hours to reset the ECU, and I added a bottle of Chevron Techron. The ECU reset seems to have made a slight difference so far. The MPG readout is showing about 3-4 MPG improvement. Again, a little early to know exactly how much it helped, if at all. The transmission seems to shift a little better, and acceleration is improved, as well as a little smoother idle.

The ECU reset was primarily to clear out any potential bad habits the previous owner may have taught the RX, such as a craving for cheap gas... I've been running 91+ since I got it, and I was questioning myself for spending the extra money. We'll see how the ECU reset helps.

numbafree

You should only need to disconnect the battery for 30 minutes.

I drive my RX330 like I stole it.89 octane. freeway commute usually go 90+ (very little traffic), floor it every chance I get (lead foot), and get 18.75-21 mpg.

when there is freeway traffic or I have one of my dogs in the car, I go normal speeds. flat, going 70 I get 29 mpg (indicated by the display).

I get about 300 miles per tank. 176k miles.

RedGemini

I only did 2 hours because I took a nap... LOL

Flat? Not in central PA...

5W40

Regular routine maintenance 2006 RX330 AWD 130K miles [210K km] got 17-18 MPG in city and 25-26 MPG on freeway running 89 octane.

If everything seems OK and all serviced as manufacture's schedule , but you still have a horrible gas mileage then check coolant temperature sensor if I were you.

RedGemini

Any way to tell if the coolant temperature sensor is bad? It seems mine runs a tad under midway, according to the gauge.

5W40

It seems your engine temperature is OK as mine did the same around midway.

If coolant flushed as schedule like 50K km interval [Canada Version] with Toyota long life coolant, Engine coolant temperature sensor should be OK, otherwise it need be taken out from engine [easy DIY but need drain some coolant first] and check the resistance as follows:

Resistance inspection.

1. Using an ohmmeter, measure the resistance between each terminals.

Resistance: Approx. 20 degree C (68 degree F): 2.32 to 2.59 KOhms
Approx. 80 degree C (176 degree F): 0.310 to 0.326 KOhms

NOTE: In case of checking the water temperature sensor in the water, be careful not to allow water to go into the terminals, and after
checking, dry the sensor.

matts6887

Im kinda wondering about this myself. I thought these second gens were supposed to get above 20mpg highway? However lately Ive only been getting in the upper teens avg mpg. I was thinking maybe my air filter needs to be changed and or the maf sensor needs to be cleaned. but short of that what else can be done? I have a 2007 rx350 which a bit under 70,000 on the clock.

matts6887

What fuse do you pull to reset the ecu? And will it do and irrepairable harm to the vehicle?

RedGemini

There appears to be 3 ECU-related fuses, so I didn't pull any of them. I pulled the negative terminal from the battery.

No issues after the reset, other than you'll have to do a relearn for the windows and sunroof.

Windows: (do this for each window using the switch on each door) lower the window about half way, put it up the whole way, then lower it the whole way. This will reset the window.

Sunroof: press and hold the tilt switch (the larger rectangle rocker button), the end closest to you. Hold until the sunroof runs a complete cycle: tilt up and down, slide back (open) and closes the whole way. Hold the button down until it stops moving. This resets the sunroof.

Note: after reconnecting the battery terminal, the first engine startup was abnormal. It was a longer than usual crank, and it actually stalled the first time for me. The second start was much more normal. It was fine after that. I took it for a drive of about 10 miles afterwards. You wouldn't have to drive that long, but a couple miles is recommended. It helps the relearn process for the ECU and TCU.