99 ES 300 misfire problems - Page 2 - ClubLexus - Lexus Forum Discussion

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99 ES 300 misfire problems

Old 09-11-17, 12:26 AM
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Originally Posted by b25shooter View Post
So, bought the little 99 es300 and it wouldn't smog b/c of random misfires in bank one. Replaced coil on cylinder 4 (long story) and the oil timing valves (both banks). Drove it a bit and it was great, and smogged. But within 200 miles, developed a misfire on cylinder 4, but only at idle or under load, and NO CODES. Note: If I idled above 1500RPM, no misfires. There were two clues to the solution: (1) no codes. All the other "misfire" solutions are related to codes. No codes, but misfire means it must be something that doesn't code; and (2) under load - which to me means timing. So, I pulled the elec for the fuel injector, and the misfires continued, but with NO CODE. THen, I pulled the cam position sensor (which feeds data to the ECM which uses that data to make the fuel injectors work) and it looked good and tested good (in resistance range), but it was a little varnished. cleaned it super shiny, put it back, and viola... all is well with the world. If the cam shaft position sensor isn't always reading the accurate cam position for cylinder 4, it misfires with NO CODE. I'm ordering a new one (mine seems a little sensitive to me) for $30 on line. I hope this helps others. I will say this... if you get misfire codes for an entire bank, do NOT go to the O2 sensors or MAF until after you've cleaned and/or replaced the oily parts (cam position sensor, oil timing valves). I have a great Solus Pro ODB reader. Because it was able to give me feedback while operating, I was always able to determine that all the sensors were fine (notwithstanding all the threads that say to blame the O2 sensors) while the misfires (code and non-code) were happening. I even got o2 codes from the oil timing valve problems, but I knew the o2 sensors were okay. Once I stopped getting the codes, but still getting the misfires, then it all fell into place. Good luck to all. This misfire issue is a real mess.
I gotta check this out - I have an RX300 that I just did knock sensors on, and it eventually (every two weeks) develops a P0302. I know the battery needs to be replaced, it's got a lot of corrosion.
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