verbatim

Short version:
My 2002 es300 had multiple misfire codes so i changed the spark plugs and checked the coils. I then got DIFFERENT multiple misfire codes and i could occasionally smell gas while driving. Changed bank2 OCV & gas smell went away. Now it is loosing power and making a hissing noise when i press the gas. Any ideas on how to fix these issues would be greatly appreciated. Thanks in advance
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Long version:
codes on 11.19.2019:
p0300 - p0304, p0306 cylinder misfire, bad coil or spark plug or oil control valve [ocv]
p1315 #4 ignition coil
p0305 #2 ignition coil
p0430
A code P0430 may mean that one or more of the following has happened:
1 - The catalytic converter is no longer functioning properly
2 - An oxygen sensor is not reading (functioning) properly
3 - There is an exhaust leak

I changed the spark plugs, and the p0430, p1315, p0305 codes vanished.
I still had misfires [shaking], I smelled gas, and car loses power when accelerating. I can't go past 55 mph. I sprayed water around hoses looking for vacuum leaks and found none.
I changed the bank2 ocv trying to fix misfires and gas smell disappeared, but I still have the other issues & these codes:
p0300 - p0301, p0302, p0304, p0306 cylinder misfires.

The plugs, coils, and fuel injectors in the front [bank2] seem to be working, and the ones in the back were working when i changed the spark plugs last week.

I'm not sure if I should change the bank1 OCV, get a new front oxygen sensor, put fuel cleaner in the gas tank, continue to look for vacuum leaks or do something else.
Any help offered would be greatly appreciated.

Coldax

Did you try cleaning or replacing the MAF?
Disconnect the battery before replacing.

Richardsr

I’m going with the front oxygen sensor first. Then go ahead and change out the OCV, put a half a can of Seafoam into a tank of 91 octane gas and go. If that doesn’t work, and do I believe the sensor will do it, consider it a little money well spent, both banks are cleared vs a Catalytic Converter. “sometimes a failed O2 sensor can cause your car to act and look like it has a failed catalytic converter. For example, if the O2 sensor doesn't allow the powertrain control module (PCM) to work properly and your engine will run rich, thus causing more emissions.”

verbatim

Thank you for the informative advice Richard. I'll put the new o2 sensor in and report back. Fingers crossed

speedkar9

When you say you checked the coils, did you do that with a multi-meter, or by swapping the coils and watching the misfire count?

omar804

1. if hosed down engine bay with water u could've caused a electrical short somewhere.
2. also check ur fuel pump,
3. if its hissing sound u have hose leak, use a WD40 to spray around to find leak.