My car is vibrating differently today. Feels like it has trouble driving. It chokes every half a second when i throttle it. After 20 miles, code 25 on the cel appear.

Code 25 - Air-Fuel Ration Lean Malfunction.

Any one have this problem? My exhaust sure does smell.

I did all the maintenance on the car including denso o2 sensors. plug/wires/cap/rotor/air filter within 4K. I just changed my engine oil and washed my car when this problem occur. Thanks in advance.
I tried to find any loose/cracked hose.

 

Are you using a non-oiled type of air filter?
Try double checking your plug wires and vacuum lines.


Also, grabbed this off alldata if it helps any:

"Data Trouble Code No. 25 - Air-Fuel Ratio Lean Malfunction

Detecting Condition

Main Heated Oxygen Sensor voltage is 0.45 volts or less (lean) for 90 seconds under the following conditions (2 trip detection);

•Engine coolant temperature 70°C (161°F) or more.
•Engine speed 1,500 rpm or more.
or
Engine speed varies by more than 15 rpm over the preceding crankshaft position during a period of 20 seconds or more under the following conditions (2 trip detection);

•Engine speed idling.
•Engine coolant temperature between 60°C (140°F) and 95°C (203°F).

or

Difference of air/fuel ratio feedback compensation value between front (no. 1 - 3 cylinders) and rear (no. 4 - 6 cylinders) is more than 15 percentage for 20 seconds or more under the following conditions (2 trip detection);



•Engine speed: 2,000 rpm or more.
•Engine coolant temperature between 60°C (140°F) and 95°C (203°F).



Trouble Area

•Open or short in Main Heated Oxygen Sensor circuit.
•Main Heated Oxygen Sensor.
•Ignition system.
•Engine Control Module.

or

•Open or short in Injector circuit.
•Fuel line pressure (leak or blockage).
•Mechanical system malfunction (timing belt skipped).
•Ignition system
•Compression pressure.
•Volume Air Flow Meter.
•Engine Control Module."

 

did you wash the engine too?

 

no, i did not. geez, i checked all the o2 sensors. my new o2 sensor is black....should that be right? while the other one i did not replace is white. the smell is getting to me. can it be a an exhaust leak too? im going to check the exhaust manifold right now

 

since i am running lean...my conclusion is that i should replace all 3 o2 sensor. my almost brand new o2 is complete burnt. What are the effects of a dead cat?

 

I was assuming that the 2 main o2 sensors on the exhaust manifold were new. So only one of them is new? I wouldn't worry about the third o2 after the cat as it just monitors a/f ratio instead of reacting to it like the main o2 sensors.

I have a spare main o2 that threw a soft CEL if you want it. Before replacing it, I drove on it for a good month without any decrease in performance.

 

thanks but i dont think i need it. I replace one o2 sensor(new) with my old sensor to try if it was the problem. the same is still there. muffler is fluttering. acceleration is choking. the smell doesnt like egg eyes. but smells like plain gasoline. i am going to take it in to an local exhaust in pasadena.

 

btw. i purchase a K&N air filter within 4k if this helps.

 

Ah ok this is why I asked on the 2nd post as it is possible that the oil from the K&N filter has gunked up your MAF/AFM. I would swap it out to a dry type filter right away.

Depending on if you have a MAF or AFM, try cleaning it out with some sensitive electronic or MAF spray cleaner. Becareful though as they are very sensitive and using the wrong type of cleaner may damage it.

Heres a thread for MAF cleaning: https://www.clublexus.com/forums/sho...d.php?t=345147

The above thread does not apply if you have an AFM though. For the record my 93 has an AFM, but they could have changed to MAFs in the later years like the SCs did.

 

id honestly go get OEM from lexus O2 sensors all 3 of them, aftermarket ones like denso or any other aftermarket ones dont have the exact same feedback to the computer and it can set codes like lean or rich because its feeding the computer wrong data.. try that first and then see if the code is still there.. but id double check the ect sensor also, to see if its working properly

 

Black is way too rich. How is the gas mileage? Possible stuck injector?

 

i have driven it that much. it killed about an eighth of a tank in 30 miles.

i think it was a bad idea to clean the MAF because my car doesnt even start any more.
i think i need a MAF sensor. anyone can help?

 

Do you have a MAF or AFM? What did you use to clean it? Did you let it dry before reinstalling it?

 

Ok first, you have a Karmen meter not a hot wire MAF. If you cleaned it with the usual products, you killed it. You do not clean these meters. Replace it.

 

not sure if i have maf or afm. but it says VAF. i cleaned it with CRC MAF sensor cleaner. i let it dry for a least 10 mins with air. I think Kaiser is right. where can i get this sensor?