Hey guys my name is Mike I am new to this forum and I own a 2001 Lexus IS300 that I purchased 3 years ago. I am from the my.is forum and I heard about this forum so here I am. Anyways I had issues with my vehicle lately for the past month. My car has been running rough at low 2rpms and it occasionaly dies on me. This usually happens when my car is warmed up and I drive it for 10-20 minutes. My CEL came up and I had it checked a few times. The first time I got a p1346, p1349 so I checked the OCV and it seemed to be working fine so I reset the light. Next time I got the light I had it checked I gotta p1349 and p0300 and all cylinder misfire codes. So i changed the spark plugs cleaned the wells cleaned the coil packs.

I finish the job and a couple days later I get the cylinder misfire codes again. I drive the car for awhile with the codes on at speeds of 55 mph plus the car seems to lose power So I redo my plugs see if everything is fine and I thoroughly cleaned the wires and the wells. On top of this I changed the pcv valve and seafomed the car through the vacuum lines. The car runs better and it has more power so I figured problem solved but the CEL codes pop up again.

This time I get p1349, p0130, p0150 for the o2 sensors and p0300, p0301, p0303. p0304, p0305 and 0306. I recheck the OCV and test again. I applied battery power to the OCV and the car stalls which from what Ive been told at the my.is forum it indicates the OCV checks out fine. On top of all of this my thermostat gauge is not operating correctly. When Im stopped and the car is idling the thermostat is in the middle but when I drive the car the thermostat gauge goes down.

any ideas? thanks

 

Welcome to the forum Mike... it sounds like you have multiple issues with the car and without seeing it, may be hard to diagnose, but I'll try and give you as much info as I can here...

First off, your multiple cylinder misfires lead me to believe its not a true misfire issue

p0130 Bank 1 Sensor 1 O2 Sensor Circuit
p0150 Bank 2 Sensor 1 O2 Sensor Circuit
p1349 VVT System Malfunction

the rest of the codes are for each individual cylinder misfire, and p0300 is multiple cylinder misfire...

There is a possibility that all of the codes are actually due to the oil control valve not operating properly... There is also the possibility (good, actually) that even though it is testing good, there is indeed something wrong with it... This oil control valve changes timing, which can affect ignition timing (and cause misfires) and the misfires could cause the O2 sensors to report incorrectly.

The first thing you need to do is to monitor O2 sensor voltage and see if it is changing as the car idles and drives... it should sweep back and forth from 0.0 volts to 1.0 volts... It is rare for both to go bad at the same time unless something else is causing the issue (which could definitely be all the misfires)...

There is also a possibility these symptoms are electrically related, in case of a failing ECU, short in the wiring, etc. which could also cause issues with the temperature gauge. How is battery voltage? Are you seeing 13 volts all the time? An alternator issue could also manifest itself as weirdly acting electronics well before you actually had a dead battery because of it... One other thing that can cause odd temperature gauge issues is if the car is physically low on coolant...

Is the car modded at all?

 

Yeah i tested the OCV with the ohmmeter and it tested within specs as written in the IS full service manual. The only mods on my car is an AEM short ram intake and hks hiper axleback. In regards to coolant it is full but Ive required to add it from time to time b/c my radiator is leaking. The battery voltage has been consistent in the 13-15 range I have not noticed any difference with the voltage meter

 

I'd love to see your fuel trims... With only an aftermarket intake, I found fuel trims so out of whack on my car until I modified the air flow signal with an Emanage, that it would cause misfires because it ran lean...

 

I'm having the same problem without the temp gauge problem. I don't have nor do I know how to use an ohm meter. I replaced the throttle control motor hoping that was the problem. I also took the ocv off and cleaned the filter, unhooked the battery to reset the vsc and vsc off light, my car did it again. Should I replace the ocv?