2008 Tundra Misfiring issue

Hello everyone,

Over the summer my wife and I got a steal on an 08 with only 80k miles on it. It's the 5.7 and we have been loving it. Unfortunately, Thanksgiving morning on way to bring stuff by the in laws house I was having trouble getting it started. By dinner time it was just straight up dead. We initially thought it was the battery as the only issue it had when we bought it was a bad alternator and that was an easy fix for us to do.

Day after Thanksgiving I was able to rock the car and get it running and the CEL was for a Crank Position Sensor. Again and easy enough fix for myself, however after a week the truck was throwing misfire pending codes and running rough. I have a little OBD II reader with Torque Pro and the pending codes were for Random Misfire and then all 8 cylinders. A few days after that I got code for misfire 5 and 7 and swapped the coils with 1 and 3 to test those. The code now came back misfire 3 and 4; this confused the crap out of me. The car was also now in limp mode and I just had it towed back to my house. Over the last 2 days I just did coils and plugs and for a day there was no misfires, and the truck was driving like it was brand new. This morning, once it had warmed up and dropped to low idle I got all sorts of pending codes; I want to say about 4 of the cylinders. Also full code for random misfire, and 3 of the cylinders.

After reading a similar post, I dont think its bad fuel (I fill both of my cars at the same place and there is no issue with my hyundai) I feel like the injectors are a low chance as its so many cylinders. My old mechanic thinks it could be something to do with a solenoid based on the firing order but I'm not 100% sure what he means. I am really hoping its not a head gasket or valve issue but at this point I don't know what else it could be or what I could check.

Any thoughts?

 

Tundras prefer OEM coils and sensors, if you installed something else that could be related to your issue. Same with plugs, and some of them sold out on Amazon or similar are not genuine.

 

Did you replace the crank position sensor? If so was it with a Toyota one or a chain auto parts one?

If you have a bad or cheap crank position sensor it will make it difficult for the ecu to properly fire the coils if it’s getting mixed readings on crank position.


I would make sure the Toyota crank sensor is in it. Clear the codes, unhook the battery for an while to fully reset everything. Start the truck and let it idle for like 20-30 mins. Let it get up to operating temp and normalize all data and sensors before driving.

Then go try it out.

My assumption is the battery died and I’m doing so gave a false crank code. If you replaced it with a cheap one this could be your problem. From reading these boards a good OEM Toyota crank sensor is a must for these engines