Hey there. For a while I have been experiencing a strange issue on my Lexus. When scanning the codes usually there's always pending codes of P0300 and then from time to time it's P300, P0301, P0303. Most of the time I don't feel any misfires and the car starts with no issues, accelerates well and drives well. There is sometimes a popping sound coming from the engine or when at a stoplight but it's very light and only when the car is cold and not warmed up. There have been 2 instances when the weather was below freezing and then the check engine light came up and was flashing with the misfire being audible. Shutting down the car and starting her again resolved the issue and there have been no active misfires like that since then. On some days there are no pending codes, sometimes there are. I have removed and changed the spark plugs, there was one coil which was cracked, so that was replaced as well. I have cleaned the throttle body, checked the MAF and it looked clean. I have ran a few bottles of fuel injector cleaner just for the sake of it. Also, I forgot to mention that the Long Term Fuel Trim in Bank 1 (where these 1 and 3 cylinders are) has been -17.95% when I first noticed the issues and doing all of the fixes I wrote (plugs, maf, throttle body ,fuel injector cleaner, coil) it got down to -12%. What else could I be looking at here? Perhaps the o2 sensors? I tried reading the data and was not sure what to look at. It seemed to stay at 0.1 V so would this mean it's bad? I'm worried it might be bad compression in the cylinders. I appreciate any feedback or ideas.
2009 Lexus IS250, Automatic, RWD, 156k kilometers,
Well if it's running that rich that has to subtract fuel you did say putting cleaner and stuff in it reduced it. That kind of shows me that it's a fuel injector problem. Perhaps they need to be replaced because they're just too worn out. Cleaning can only go so far. If it's spraying erratically and doesn't burn, it will then run rich. Cleaning doesn't always fix that. Of course. There's a lot of things that can do that are blowing head gasket, weak ignition system all kinds of things. If I were you I would erase all the codes. Take it for a quick road trip and see which code pops up first and start with that analysis
