dallison

ok, my co-worker has a 99 rx300 with 90,000 miles.
he had the typical p0171 and was running a k&n filter. i had the same problem and replaced with a reg ular air filter and replaced the maf filter, problem solved.

now he is getting cel of 1133 &1153 & still 0171. also when applying the gas when coming from dead stop to pull out it feels like it's lagging and then picks up normally.


when driving on the highway and he goes to accelerate, not to the floor, it lags then picks up, l;ets off the gas and reapplies the gas and then it's ok.

i did do a lot of searching here and could not find one definitive answer. some led me to believe it;s the o2 sensors.


but it almost sounds like the maf sensor that was replaced has gone bad already.


any suggestions???

Lexmex

The lagging sounds like maf issue after the CEL is initially reset (I know from experiences). However, this usually goes away after a while. Usually, that combination mentioned sounds like one of the O2 sensors. Some more advanced OBDII scanners, have a feature that can show if one or more of the O2 sensors is dead or giving proper readings. P0171 can accompany the above errors, but does not mean a dead MAF.

At what RPM is your idle when in D gear?

dallison

idles @ 1100 rpm in park (cold) and in drive it was jumoping between 1300-1500 rpm

Lexmex

I would still get the O2 sensors checked out as I mentioned. Don't need Lexus for this, but many mechanics have an OBDII scanner that can read O2 sensor readings.

On cold weather days where I live my RPMs shoot over 1000 and only if I go super fast slamming it at WOT will I get a P0171 error (too much air/lean) but not the other codes. However, I don't doubt that at closer sea level where the RX300 is going to be more powerful that you will encounter very different readings with regard to fuel/air (higher oxygen content) and rather than being an O2 sensor having gone haywire, it just is a sensor reading. Could be cooler air this time of year. Only way to know is to get the O2 sensors checked out as I mentioned earlier.

dallison

i have an inexpensive actron obd II reader, but i will prob need a more adnaced model for this

justfixit

P1133 Bank #1 air fuel ratio sensor
P1153 Bank #2 air fuel ratio sensor
RX300 has Air Fuel Ratio sensors pre cat and O2 sensor post cat.
Correct you will need a little more scanner to monitor A/F sensors

dallison

he took it to autozone and they read the codes with a better model and it read that it was the maf, so they replaced it for him and i gave him my reader to erase the codes, so we will see in the morning

Lexmex

There are some very top of the line scanners that can even look at the snapshot at the time the error occurred. Some of the laptop programs I have heard about have this feature.

What I am always amazed it is that I use no air filter, bad gas up until now (really good quality the new premium down here), and just a dirty maf once from the K&N, but only an occasional P0171 error from the air/environmental conditions.

dallison

well he is still having problems.

i just replaced the exhaust gasket in front of the cat. it was a ***** b/c the one bolt broke off and i had to drill it out with a carbide bit.

i needed to get tha fixed 1st to clear the codes to re-troubleshoot.

he still had 1133 and 0171 after i read them and then cleared.

i wonder if it may be a sending unit or fuel pump of some sort.

the lights really don't come on until he fills up.
the codes come on and the light goes off after he gets around 3/4 tank.

still puzzled

dallison

he took it to the toyota dealer a couple weeks ago and has an o2 sensor and the canister replaced and since then no problems