tomstep2

Alright,

I am coming to the true experts here. My wife pushed the limit getting to the gas pump on our 99 RX300. It was to the point that it was starting to sputter and buck when she pulled up to the pump.

She filled the tank with 93 octane (as she always does) and drove 60 miles with no issues. Then the CEL came on. We checked the oil, tranny fluid, antifreeze, etc...all okay. I thought maybe the crud in the tank caused some codes to trip. Unplugged the negative battery terminal for 30 minutes to reset the computer. No more codes and drove like new for a few days.

Then, the CEL came back on and it started to idle rough. Almost to the point of stalling. I then took it for a little drive. Only rough at idle, smooth as silk cruising the highway with no noticeable loss of power.

I had Autozone pull the codes and it showed the entire rear bank misfiring. I bought some Lucas Fuel Cleaner and put it in the tank. When I started the car after adding the fuel cleaner, it was instantly smooth again. The CEL was still on and I figured that I would have to reset it again. On the drive home, the CEL went off on it's own. It has been perfect for a few more days.

Then over the weekend, I had to take it to the city and on the interstate. Still no problems. I then went to pass a car merging onto the interstate too slowly and the CEL came back on and all of the problems previously described.

When I got home, it was still idling rough. Since it has been two tanks since I added the Lucas Fuel Cleaner, I decided to add some Seafoam to the tank. It has been running better, yet the CEL is still on.

Does anyone have any ideas of what is causing all of this? The engine is only a few years old as Lexus replaced it due to the oil sludge problems.

Please help!! Any and all input are appreciated. I don't know why, but I keep thing it is the IAC valve...

Tom

salimshah

The RX thinks it is the code and that is what you should zero on to. If it is fuel related, I would reset is couple of times and run couple of tankfulls.

You may need to have the injectors serviced.

Salim

tomstep2

Okay, here are the codes that were pulled by AutoZone. P1354, P0505, P0300, P0302, P0304, P0306.

Would a faulty PCV valve cause these?

It was running great after a couple of tankfulls and then started idling rough again. I cleaned the MAF sensor and it idled a lot better until I drove it. Once again, the engine was replaced by Lexus 3 years ago due to oil sludge and this has me really concerned.

Could it possibly just need a tune-up?

Thanks!

Tom

tomstep2

Do RX's have an inline fuel filter, or only one in the tank?

maxSteel

tomstep2,

This page lists trouble codes http://www.obd-codes.com/trouble_codes/

I would buy a code reader, clear the codes, and them watch for the first code that comes up. It might be causing all the other ones.

tomstep2

Just had it serviced. All that was wrong was the VVT Solenoid was malfunctioning. Had a new solenoid installed and no codes and runs like a top! Thanks for the advice everyone!

salimshah

were you getting a CEL?

Salim

tomstep2

I was getting the codes mentioned above. The service tech reset the codes and then ran the car to see which code came up first. The P1354 came up first, then the P0300 after that and so on... The service tech advised that the VVT Solenoid was malfunctioning randomly and that was the root cause of all the other codes. Since the service was done and VVT Solenoid replaced, it has been running flawlessly again.

Thanks to everyone here for all of their help and suggestions.

Tom