General Tech Good at troubleshooting? Have a non specific issue? Discuss general tech topics here.

Misfire codes

Old 05-16-2018, 03:46 PM
Junior Member
Thread Starter
Join Date: May 2018
Posts: 1
Default Misfire codes

I'm hoping someone here can help me out. I have a 97 toyota avalon that I am trying to raise from the dead. I've done a bunch of work to the engine and now I am left with a p0300 code as well as p0301 and p0305. I have replaced all spark plugs and wires with new ngk plugs and wires and still the same codes pop up. This engine was junk when I got it because the previous owner never changed the oil regularly and when he did he used cheap oil. In any case, I had to replace the front cylinder head due to lack of oil eating up the camshaft. I've also changed the timing belt and water pump plus pullies. I have changed out the valve cover gaskets and spark plug seals as well as intake gaskets and plenum gasket. Yesterday, I noticed oil in the spark plug tubes for the front cylinders that the coil packs go in so I took the spark plug seals off the front valve cover and added some black RTV silicone which is now keeping the oil out and sealing like it should. The back cylinders do not have any oil in them at all. I figured after I got the oil out and cleaned the ignition coils the misfires would go away but they still remain. Any help appreciated!
Old 05-17-2018, 11:51 AM
Super Moderator
Join Date: Jan 2008
Location: PTW
Posts: 11,738

Here is the list of possible problems.
Ignition system
Fuel line pressure
Compression pressure
Valve clearance not to specification
Valve timing
Mass air flow meter
Engine coolant temp. sensor
Open or short in engine wire
Connector connection

Do you have access to a scanner that can check the rear cylinder bank 02 sensor output for rich/lean mixture?
Related Topics
Thread Starter
Last Post
General Tech
06-18-2016 07:21 AM
Engine & Internal
09-19-2008 02:50 PM
General Tech
07-28-2008 09:34 PM
General Tech
01-24-2008 09:41 AM
General Tech
06-11-2007 03:37 PM

Thread Tools
Search this Thread
Quick Reply: Misfire codes

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.