Toyota Tundra Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter · #1 ·
'01 V8 A/T 4x4 150k
Bank 2 O2 sensor replaced at 135k
Suddenly (on 1/2 tank of new gas) reading codes for misfire on all even cylinders (bank 2) and rich mix b2 ,BUT lean mix on b1. Runs like crap, multiple misfires at all RPM. I understand that a bad O2 on b1 might richen the mix and cause the engine to run rough, but what could make all the cylinders on one head randomly misfire while the odd cylinders are doing fine? Also; no MIL / CEL. I'm stumped. Anybody?
 

·
Super Moderator
2015 Toyota Tundra DC SR5 5.7L
Joined
·
8,559 Posts
What sensor did you replace B2 with? If you're experiencing a cascading misfire, the ECU must be at least pending the P03XX series codes. Have it checked by someone with an OBDII scanner.

The solution might be something as simple as replacing B1S1 with a Denso fuel-air sensor #234-4169.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #3 ·
I have all the codes for misfires of all bank 2 cylinders. The fuel trim is about 25% off between the banks, but when I unplug the air flow sensor they pretty much even out (although very lean). I cleaned it without much improvement so I'm trying to find a replacement. Hope this solves it.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #7 ·
Not sure about the brand of sensor and don't really care. It works.
Turns out the wacky fuel trim and misfires were a valve timing problem. I had replaced the timing belt and pulleys 60k ago and was hoping to run another 30k before changing it again. Turns out the tensioner pulley bearing failed and it loosened enough for the belt to run on it without breaking, but also loose enough to slip a few notches on one of the cam sprockets. The tech said it was 3 notches off. I kind of wish the belt would have snapped; I probably would have figured that out on my own, but based on the scan and the way it was running I figured a sensor or computer issue. I really hate paying for stuff I can do myself, but the diagnosis and the quick turnaround was worth the $962.92 they charged me (which included a water pump).
 

·
Registered
Joined
·
541 Posts
Be happy that it only cost $962. Had the belt slipped further or snapped altogether, you'd be facing a much more expensive repair bill. Valve jobs on these engines don't come cheap.
 
1 - 8 of 8 Posts
Top