omanely

Ok... well i have been having alot of problems with my rx 300 lately and I could use some advice from you guys.. first off I had multiple miss fire codes so I replaced the spark plugs with bosch iridiums. Trans. was also shifting poorly so I serviced the trans. Truck ran -ok after that but still had a cel on with codes p171-141-1346-305-303-301-300. Timing belt was just done, water pump, thermostat, coolant sensor, the o2 sensor under drivers seat floor and cleaned mass air meter...
Truck now runs like crap..no power...missfires...please help....thankssss..

Nad1370

First off. Welcome to CL.

2nd--get rid of those Bosch plugs you just put in and replace them with Denso's or NGK.
Bosch plugs don't usually play well with Toyota Motors.

P1346 indicates a bad Oil Control Valve(OCV) in Bank 1--Firewall side. Hence the misfires at Cyl. 1-3-5.

Address these issues first then report back.
Welcome again.

code58

I 2nd what Nad said. Unfortunately Bosch doesn't play well with a lot of vehicles. With T/L building the cars with one of the finest plugs ever built, it never ceases to amaze me that people use aftermarket plugs. I also say ditch the Botch (or I guess it's pronounced Bosch) plugs. For a big company, they make some bad news plugs.

hypervish

X3. Get rid of the Bosch...Then see what codes come up. Get some NGK's or Denso plugs.

Gomer1

Yeap, get rid of the plugs. In addition to the recommened, I would also clean the mass air flow sensor.

omanely

Well I REPLACED THE PLUGS AND IT RUNS THE SAME... I REMOVED THE TIMING COVERS AND RECHECKED AND RESET THE BELT MATCHING ALL MARKS... RAN ENGINE STARTED FINE TILL RPM DROPPED TO IDLE THEN AS IT WARMED UP I CAN HEAR LIKE A LARGE VACCUM LEAK THROUGH THE INTAKE AND MISSFIRNG THROUGH INTAKE AND SAME CODES APPEARED FOR MISFIRES AND 172 AS WELL AS 1346...CAR IS DRIVING ME CRAZY..STARTING TO THINK MAYBE THE ECM IS GOING BAD....GETTING READY TO GIVE UP AND SEND IT TO THE STEALERSHIP...ANY OTHER IDEAS....

omanely

THANKS FOR THE ADVICE BY THE WAY. THE CAR IS RUNNING ON 3 CYLINDERS. CAN'T REVERSE UP DRIVEWAY. WHAT THE f### IS GOIN ON.....

omanely

Well I REPLACED THE PLUGS AND IT RUNS THE SAME... I REMOVED THE TIMING COVERS AND RECHECKED AND RESET THE BELT MATCHING ALL MARKS... RAN ENGINE STARTED FINE TILL RPM DROPPED TO IDLE THEN AS IT WARMED UP I CAN HEAR LIKE A LARGE VACCUM LEAK THROUGH THE INTAKE AND MISSFIRNG THROUGH INTAKE AND SAME CODES APPEARED FOR MISFIRES AND 172 AS WELL AS 1346...CAR IS DRIVING ME CRAZY..STARTING TO THINK MAYBE THE ECM IS GOING BAD....GETTING READY TO GIVE UP AND SEND IT TO THE STEALERSHIP...ANY OTHER IDEAS.... tHANKS FOR THE ADVISE BY THE WAY. IM RUNNING ON 3 CYLINDERS.

Nad1370

Whoah there Oman..Easy with the CAPS..

That's a start by replacing the plugs.
Now you have to address your P1346 code which is an OCV. (check 2nd post in case you didn't read the whole thing)

Part should be <$90. Held by just 1 10mm bolt. <10min to do the job.

omanely

Whats the difference in vvt and ocv..

omanely

Also 1346 has to do with timing and that's not off at all

Nad1370

VVT--variable valve timing. Just as it describes..constantly changes timing via hydraulicaly.
OCV--oil control valve. This baby controls the oil flow to change timing.

DOHC--2 camshafts per bank but only 1 gear for the T-belt. 2 internal gears are meshed for both camshafts to turn. This is where the whole VVTi works.

So yes, looking at your timing marks indicate it's timed right. but as soon as you start your motor, if an OCV is bad....your motor Sir, will be out of time.

Here's a link that has the same issue as your but his' was on Bank 2 Radiator side.
....and guess what...the OCV was the culprit.

https://www.clublexus.com/forums/rx-...304-p0306.html

omanely

Ok so I replaced the OCV.. Nothing has changed. same codes coming up, 300, 301, 303, 305, 172. I switched coil 1 to 2, to see if it could be the coil. same codes again..??

omanely

got the car to the dealer, found out both cats are bad, reason for the misfire in bank 1.

code58

I would advise getting it out of the dealership and going to a muffler shop to have the cats replaced. Unless you are independently wealthy it's going to cost you a Kings ransom to have them replaced there. Need to find out why they went bad. In normal driving they shouldn't have become plugged. Don't want to have to do it again because the original problem wasn't addressed.