P0300 permanent code and more.

My 2010 5.7 started getting the P0300 with p0301 through p0308 also. In the same time frame I installed a new starter and AGM battery. After the codes I replaced the spark plugs and coils with the Denzo factory replacements.I cleaned the throttle body and repaired a broken ground strap under the transmission. Still getting the codes.
When I start it in the morning or after sitting awhile it throws the codes. I can clear them with my reader and restart and it runs smooth with no codes. I can drive and restart it like normal. Once it sits for awhile it will code again. And again I clear the codes and it runs fine. Don't want to keep throwing parts at it. Any help would be appreciated thanks.

 

I would swap both cylinder 1 p0301 and cylinder 8 p0308 to other cylinders for example cyl 3 and 6. P0300 is multiple misfires. You can also try swapping the old ones back on those specific one. Ensure all harnesses are fully seated.

 

Get the freeze frame data from the ecu from 2 or three events and post them up. It's tells what the conditions were that caused it.

Any chance of water in the fuel?

 

Thank you for the replies. No I don't think water in the gas is an issue, but I haven't check. I will try moving the coils to see if it follows. Good idea. I will try to post a few freeze frames when I can. Thanks again for the input.

 

I bring up the water as you never know and once the vehicle starts moving it can mix with fuel and leave the bottom of the tank. But when it sits, it sinks to the bottom.

My guess is you have a fueling issue.

You look at the short and long term fuel trims too once it hits closed loop. But maybe all this happens during open loop?

 

When is it an open loop? Whenever I check it's alway's a closed loop.

 

About the duration the B1/B2 S1 sensors take to come up to temp and report the AFR back to the ECU. Once it has data from the sensors, unless real cold, it switches to closed loop control with the ECU.

Freeze Frame Data will capture this. When is the last time the battery was disconnected?

 

Open loop when it's cold to nearly operating temperature I think. If a pre-cat O2 sensor goes bad it will remain in open loop and will consume more fuel.

Close loop at operating temperature getting feedback from pre/post oxygen sensors, MAF and other sensors.

 

Thank you both again. Battery was disconnected 2 weeks ago.
Update: Yesterday I put a can of Cataclean in my 1/4 full tank. Drove about 30 minutes and filled up with ethanol free gas. My XTool7 shows the only misfires happen at startup. Count is between 13 and 34. O2 sensors are all reading good and catalytic converters temperatures are 750 pre and 480 post.
Seems to be running better and faults haven't come back in yet.
Love my Tundra and I hope this is getting closer being fixed. I almost have 222,000 miles on her.

 

Check the negative terminal for damage on the battery hook ups. I'm at 270k and the grounding point to the firewall severed, and I was getting a random misfire in Cyl 1 on start up, and then I think it went to Cyl 6 or 8. I didn't swap anything, but when I pulled cyl 1 coil and went to remove the spark, I noticed it was loose as well at the same time my coil pack dropped behind the battery and I found the loose ground. I posted about it here somewhere. It took me a while, but I noticed the negative ground wire to the driver side fender was hanging out.

 

Update.
It ended up being my Crankshaft position sensor. About a week or so before the misfires started I got the code for the Crank sensor. I replaced it with one from O'Reilly.
Ran great for a week, then misfires. After all the checks I went through, I finally changed the generic sensor for a Denso sensor and BAM. No more misfires. So glad I got my tundra running great again. Thanks for the help and insight.

 

Denso parts are always your best choice. Keep that in mind when the alternator dies.

On the Lexus forum people chase gremlins for months, only to replace their new alternator w a reman Denso and bam, problems solved.