sandipvyas

Hi, this is my first post. Glad to be part of Club Lexus.

I have a 1999 lexus ls400 with 233k. Running without issues prior to a battery change 1 week ago. Ran fine the first day, then had rough idling the next day with engine light and VSC light on. Went away the next day and was fine for the next 6 days. Today, back to rough idle and the same engine and VSC light. The check engine was also flashing at times today. Had codes checked. 02 sensor bank 1 sensor 1(was listed as pending), variable valve timing system malfunction(confirmed), misfires in cylinder 1,3,5,7(confirmed). The very first code listed was P0300 for random multiple misfires. Looking for some assistance as to why all of a sudden these codes. I have read that the battery change can be responsible for timing issues. Also, the rough idle is not all the time. There are times that the car ran fine today, nice and quite idle. I have driven approx. 100-150 miles since the battery change. Thanks all for any insight into this situation.

Moarpower

Firstly it sounds like the o2 sensors need replacement.

Those misfires are the entire left bank. If that is accurate you will be running very rough indeed and will burn and melt your left catalytic converter due to the fuel not burning. As it's the entire bank, if not just the o2 sensors, I'd think coils could be dead, however the coils feed both left and right on my 90 and I'm sure it's the same in your case.

Sometimes when changing a new battery that's a higher voltage or CCA rating and changing to a stand alone Ecu, the old Ignition parts can die due to the change in amperage and signal. Possible.

Yamae

I'd rather think it's a cam timing issue.
A skipped cam timing often causes your type of problem. I'd check the OCV first and the next the timing belt if the OCV function was perfect.
The OCV is the Oil Control Valve which control the VVT. Remove the OCV and check it. If it's stuck, you need to replace it. If it's badly clogged, clean it thoroughly but you also need do clean the OCV filter built in the cam shaft cap which requires you to remove the cam cover.

Moarpower

For the timing to slip after a battery change, then run fine for a week then go out again seems a bit coincidental. Certainly sounds cam related. Could be a cam sensor. Would be funny if the sensor was somehow unplugged or loosened during the battery replacement

fixmiester

I suspect a bad battery connection, or ground cable connection. Lots of threads on CEL and VSC due to low cranking voltage caused by weak battery or bad connection. Check voltages with car on/off, under current load, etc. May need to look at alternator output with a scope to see if you have any bad diodes in the rectifier assy. Those can cause electrical noise that confuses the ECU.

sandipvyas

Thank you for all of your insights. Finally was also able to talk to a trusted friend/mechanic of mine who recommended the OCV replacement after hearing the symptoms, history, and codes. I will likely be ordering it from lexuspartsnow.com which sells genuine lexus parts for $110. It is bank 1 on the drivers side so from what I have read and viewed, it is the easier side to make the replacement. I will do it and send an update. Any other thoughts are welcome and appreciated.

Thanks again!

Scraape

it is your oil control valve. Relatively easy replacement, just be cautious removing old valve and installing new one. The VVT solenoid is the one on the passenger side bank. Not sure if that was bad or not but i replaced it anyways.

Read this thread:
https://www.clublexus.com/forums/ls-...ts-people.html