JemP

Took the RX for a drive today, if I dont give it any real load it goes up and down through the gears without problem, engaging and disengaging overdrive all works correctly. I can also work it up and down the box using the manual buttons too. But the minute I try and floor it, it bucks!
Didnt have a chance to check for fuses to get the obd thing working as it was raining too much, try tomorrow

kalali

This may be a pure guess but I had a similar issue with another vehicle and it was a faulty throttle position sensor. Not sure if this would apply to the RX.

JemP

Right, I havent had much chance to work on this due to overseas travel, but I have still got the problem after replacing the MAF, replacing the TPS, changing all spark plugs. I am now thinking ignition coils. Reason being I have a bit of a rough idle even after changing spark plugs, and I had a similar problem with my Jaguar, which went into "Restrictive Performance" mode, which is limp home mode, and cut the revs over 3,000 revs!
I still can't get a device that reads my OBD11 and havent pulled the codes yet, so I am going to bite the bullet and pay for a local garage to pull the codes, and see where we go from there.

JemP

OK, i am revisiting this now. I felt that the car was in restricitve mode, so I checked the coils, when I pull two of the rear coils, there is no difference to the engine revs or anything. That suggests a coil problem. I will be putting two new coils on tomorrow.

sktn77a

iTrader: (2)

Do yourself a favor and buy a cheap OBDII reader. Check e-bay. You can pick them up for under a tenner.

JemP

I have three OBDII readers, all of them work on my other cars, none of them work on the Lexus. So that doesnt help.
I've found out this morning that changing bad coils for known good coils makes no difference. Its like there is no power going to the rear 3 coils, so all of the rear bank seems out of action! Can these things run on 3 cylinders??

ATLs460

You may have a wiring issue with your OBD port. My Actron scanner will scan literally anything from GM's to BMW's and everything in between.

JemP

I finally got to the bottom of this with the help of a very good auto electrician who managed to read the OBD2. I had a coil problem, which a new coil fixed.
More importantly he was able to reset the OBD2 to get out of limp mode, and we are back in business!!

sktn77a

iTrader: (2)

Bizarre! I have a cheap $10 OBDII code reader and have no problems on my RX300. What code reader did your mechanic use?