2008 ES350, misfiring when car warms up, getting P0300, P0302, and sometimes P0306, have changed plugs, coils and swapped fuel injectors still misfiring, any ideas

 

Check the compression on those two cylinders.

 

Anything else??

 

A previous poster with a similar issue found his coil wiring at fault. A shade-tree mechanic had messed up the wiring in the process of replacing his plugs.

What led up to the misfire codes? Had any work been done recently, prior to the codes?

 

so that’s interesting because the wires had been redone and weren’t seated correctly and a couple pulled out easily… I redid them all and still getting a misfire, my theory is those plug wires shorted the ecu… thoughts?

 

The coil wires can be damaged during replacement. Check them carefully for breaks etc. including Squirrel/rodent damage.

 

Checked wires again to make sure… they look good

 

Anyone have the wiring diagram for the ignition coils so I can verify the wiring is correct

 

Sorry, I don't. My 2011 ES has been so reliable, I have yet to need the shop manuals.

Knowing your wiring was redone, I would certainly focus on it. If the engine runs well, but simply throws misfire codes, I doubt any of your wiring is incorrect, so you likely don't need a wiring diagram to fix it. Make sure all your connections are clean, tight, and protected from the elements. If any of your connectors are broken or compromised, replace them, or have them replaced. If you aren't experienced with automotive wiring, you may want to have it done professionally by a shop that specializes in this type of work. However, I don't recommend you take it back to where your recent re-wiring work was done. They likely are responsible for your continued problems, so I wouldn't trust them again. Ideally, they should refund whatever they charged you, if the misfiring codes are due to their poor work.

 

You can join the Toyota Technical Information System for 2 days for $20 and see what you need to check the wiring is correct. Plus anything in the service manual.
https://techinfo.toyota.com/techInfo...tis&_nfpb=true

 

I’m pretty experienced with wiring, I’m an aircraft electrician, bought the car with the misfire so I’m thinking the bad wiring job shorted out the ECU, it does actually misfire so definitely have an issue, but yes wiring is tight now

 

How's the misfire manifesting, i.e., audible, stuttering, lagging, smoking? Is it worse under some conditions than others? Is it misfiring only when cold, or only after warm up?

How many miles on your ES? Any signs of head gasket issues, such as cooling system issues like high temps, low coolant level, signs of moisture in oil (milky goo under oil fill cap)?

Any vacuum leaks resulting from hardened or cracked vacuum lines, or vacuum operated components?

I'm racking my brain as you've done a great job already tackling the usual suspects.

 

thanks for the reply, it seems to misfire only after warming up, if driven for a while it’ll start lagging and stuttering but for the first 15-20 mins you can’t notice anything

 

159000 miles, no signs of coolant in oil or moisture, no cooling or heating issues, I’ve inspected all the lines for leaks and can’t seem to find anything, except I noticed something I thought was weird about my air box, will post pics when the sun comes up…

 

Any leaks in the air supply between the MAF sensor to the throttle body could cause this. Has your intake manifold ever been removed? Perhaps one of the manifold-to-head seals is leaking after the heads heat up.

When cold, the richer fuel air mixture could be masking a possible vacuum leak. Then, when the engine heats up, the leak could cause a "too lean" condition.

Just spit-balling here. Good luck!