satz

HI all

I know this has been asked before, but when I did a search it came up with about 496 results. I didn't have time to open each thread to see. The few that I did open didn't seem to give a straight answer..

On my 07 RX350 I've been getting dramatically worse fuel economy after trying a tank of higher octane fuel to try to get better performance. Ironically it seems much worse. To the tune of approx 40% worse with exactly the same driving pattern.

I've gone back to my usual 95 RON (Australian rating), but the economy is still as bad, plus the engine just seems to be not as 'lively' as it was prior to trying out the higher octane fuel.

I'd like to reset the ECU to see if that helps. I asked the dealer how to do it. They said it can't be done.

Q: Is there a way to do it that does not involve disconnecting the battery for 30 minutes? Perhaps pulling some fuses or something?

please try to get back to me soon as otherwise I'll take time off work to go to the dealer.

many thanks

S

Rainbird

Disconnecting the battery for 30 minutes is the best way. Why would you not want to do that? Resetting the driver positions, windows, hatch, moonroof and radio stations is a simple 15 minute job.

satz

I guess.... but still hope someone can point out which fuse (if any) can be pulled out instead of going the battery disconnect route.

RX330inFL

Not one but two fuses.

Engine bay, remove the EFI NO. 1 and ETCS fuses for more than 60 seconds. They are labeled on the cover. You can also find their location noted in your Owner's Manual.

satz

hi all
thanks for the replies so far.

Was wondering... if I disconnect the fuses, does that affect the windows, rear power door, seat settings, etc? I read another post which said it might.

Also, in either case (battery or fuse disconnect), would I lose my saved destinations on the inbuilt SatNav?


cheers

Satz

RX330inFL

If you check your Owner's Manual you can see the systems affected by those particular fuses. As you are not disconnecting the battery you should not lose any settings for other systems except those associated with the two fuses.

lexus114

The best way is a a hand held scanner.

HtownBlue

After a set amount of engine cycles the ECU will adapt to the different fuel. As well as any changes after the first changes. It takes a bit of driving. You essentially effected the efficiency of the burn and thus the O2 sensors gave the ECU data to change the duration of the injectors opening. This can and will change back given enough cycles with a new set of data. One caveat: air temp can and will effect this. The ECU needs a steady set of data with variables like air temp in a similar range. Until the ECU gets this, it will not change to the new fuel type.

Patience should help. I wouldn't do anything until I've ran the car a few weeks as is.

satz

I wonder if this is what the Lexus service does everytime I send my car for service? It always come up feeling 'fresh and nippy' again for a couple of weeks.

I asked them yesterday about resetting the 'learning' program or ECU, and they said point blank it couldnt be done.

I'm going to try to find the 2 fuses tonight and give it a shot. My owner's manual (australia) has no details about the fuses. Just have to rely on the diagram under the fuse box lid to identify which fuse does what.

cheers

S

RX330inFL

Technically, all you are doing by removing those two fuses for the duration is to clear any DTC (Diagnostic Trouble Codes). This is all that disconnecting the negative terminal on the battery for an extended period of time does. But, I figured that was what you wanted.

Even though it is the US edition, you might find our Owner's Manual to be of some guidance:

http://drivers.lexus.com/t3Portal/do.../sec_04_03.pdf

satz

Many thanks for the link to the manual.

Far more detailed than what I have in my manual downunder


cheers

S

RX330inFL

Here is the initial jump point:

https://secure.drivers.lexus.com/lex...nual-search.do

satz

Anyone know if the ECU reset also clears the learning that the accelerator does?