2000 RX300 202k miles on it. Having sputtering issues, hardly noticeable in park but can feel it in reverse and drive, mainly in 1st and 2nd gear when I'm trying to take off, it eases up once I'm in 3rd or 4th gear but it will still sputter if I try to accelerate too much. It's like its missing a little bit, if I step on the gas a little more to get it to go, the check engine light flashes about 10 or more times then goes off and stays off unless I try to accelerate too quickly. Thought it was my plugs, they've been in there awhile and they wasn't OE but supposedly was OE equiv. so I went ahead and got the NGK that it calls for, thought it solved the problem till it got up to running temp, where it always stays once its warm and then it starts sputtering. I've already done these before this issue, MAF sensor cleaned, new Denso rear bank A/F Sensor. Could it be vacuum because i did notice where the vacuum lines run over the top and in front of transmission and down the front side of trans, the clip that holds them to the water hose was unclipped from the water hose, so maybe they were blowing and rubbed a small hole in one of the vacuum lines from rubbing on the front of the trans?

 

Do you have any codes associated with CEL?

Salim

 

Can't have A/Z check the codes because the light don't stay on, it comes on when its under a load, mainly trying to get up to speed then I'll ease up and it goes off, counted 7 flashes, then 13 flashes and then 11 flashes with a short 12th flash, don't know if that helps. I'm currently looking for a scanner to purchase but I want something that will tell me codes even if the check engine light isn't on.

 

P0300 & P0305, If someone can lead me to what the voltage should be for the front A/F ratio sensor/O2, I got my scan tool in today and I pulled those 2 pending codes and I can watch Live time on sensors, etc. I guess I should swap out coilpack 5 with 1 of the old ones that still work and see if it's the coilpack but I'd rather just check the A/F sensor before I pull the coilpack, all tips etc would be greatly appreciated

 

No one else has responded so take my post with a pinch of salt.

The O2 system monitors oxygen moles [read up under Chemistry if interested] as air enters the engine and the then monitors oxygen moles at exit of the cylinder. Computer then determines the amount to fuel that needs to be injected to have a complete combustion. Now if you have misfires then there was no combustion and the Oxygen monitoring loop will likely throw a error code.

I would suggest, first fix the misfires and once the engine is running smoothly, check the Oxygen codes.

Salim

 

Id check a couple of things. First fix the misfire on cylinder 5, you can move the coil pack to another cylinder, see if it moves. But its on the back, so that wont be easy. Depending on how old the spark plug is, that could be the issue. But I would say its prolly the coil pack, cause its happening when it gets hot. Once you get that right...check engine temp(Don't go by the gauge, use a meter that reads actual ECT output)...and see if the engine goes into closed loop operation(Swaps fuel control from the ECT to the AF sensor. If it isn't swapping, or not getting hot enough, then id suspect either the ECT, the thermostat is stuck open or possibly the AF sensor, the rear one.