I have a 1999 RX300 with 167,000 miles on it. Never had any problems. Took it out on some errands today and it was fine. Came home, let it sit for about an hour and went back out for a couple of more chores. By the end of the block, it was really chugging, not shifting gears, but not revving up either. First I thought it was the transmission but now I'm not so sure. Shifted to neutral and tried to give it gas and it still did not go much past 1000 rpm. Sounded like it was going to die. Hooked up the scanner and it gave me a P0172, something about bank 1 being too rich. Any ideas? Don't really want to drive it as is. Thanks in advance.

 

Have you tried disconnecting the battery and then reconnecting and starting?

Also, what happens when you just start it up and let it sit there and run?

 

Sounds similar to a plugged cat converter IMO

 

Started it up today, let it warm up for about ten minutes. Everything sounded fine, no strange sounds. Took a spin around the block and same thing happened. Wouldn't rev above 1000-1500 rpm's but I did notice that it shifted into second gear. Don't think it's a transmission problem. Checked the codes and their was still the pending P0172. I then disconnected the battery for a few minutes and rechecked the codes. All clear, as expected. Took it for another drive around the block and had no issues, everything worked as I expected. Leads me to believe that a sensor is going bad and is causing the computer to limit the rpm's, speed, etc. I know this happens when an ignition coil goes bad, this is a similar problem. Any thoughts?

 

Let's see if the error pops up again.

 

Still no errors, but I am driving around with a 10mm wrench and code reader just in case

 

I always carry a code reader and 10mm wrench.

 

Forgot to mention, I also have an extra ignition in coil in the glove compartment.....you never know...

 

I've got that, too, but carry it one of the rear compartments.

 

CEL is back, now the code is P0171. I replaced the sensor on bank 1, next to the firewall about a year ago or so. Thoughts?

 

Reset the code and see if it comes back. Likely issues could be a dirty MAF, air filter needing cleaning, IACV needing cleaning, fuel injectors clogged a bit (so run some fuel injector cleaner in the gas). Finally, sometimes weather is the culprit including abrupt temperature changes.

 

I had a similar situation with the p0171 code. This is the worst code you could get because it could point to an exhaust leak, vaccuum leak, to a bad sensor, etc. I have read that a vaccuum leak will cause the chugging and also read that the hose behind the air filter box gets knowcked off sometimes during an oil change/air filter change. I would start there, then look at your exhaust manifolds and look for cracks, then take it to a Toyota garage if you cannot see anything in either of these cases. You may have BHG . . . the symptoms you describe replicate what I had in my Acura . . . which led me to buy the RX300.

My problem on the RX300 ended up being the AF Ratio sensor, but I messed around cleaning the MAF, cleaning this and cleaning that, that I could have damaged my engine by not taking it to a garage - Toyota garage. My fuel efficiency doubled and the vehicle runs strong - 185K miles and still strong. Don't ride a round resetting the computer because the car is not problematic when properly maintained. If you are not a diy guy, take it to a garage. It may cost a little initially, but worth it in the long run.

 

I hate to say this, but there are some problems the dealer is best equipped to deal with (Toyota or Lexus). This may be one of them. I had a "bad coil" code several weeks back (actually, 5 "bad coil" codes). It would have taken me all day switching them around to find out what the problem was. The dealer was able to locate a single bad coil and replace it within an hour!