Cracked manifold = running crappy?

Please tell me that the visible crack on my exhaust manifold could be drawing in enough air for this thing to run crappy. I just noticed it after replacing front pipe and O2 sensor. Please please please...

 

I bet it's sounds crappy anyway.

 

I bet it could...is it throwing a code too, P0420?

 

No codes. Just running crappy. Originally I thought it was running lean but it’s actually running rich. The O2 is reading all types of crazy along w/ the fuel trims. I’m assuming this is my problem. Cracked all to crap. Replacing it in an hour

 

Not as crappy as it runs.

 

Surprised it doesn't throw a code, I would think the O2 sensors are reading odd data likely due to the crack. It should run better after you replace it.

 

I hope like Hell so...

 

My manifold was cracked bad and it felt like I had to put the pedal to the floor in any gear to go anywhere

 

Weeeeeee, it does run better! I’m kinda paranoid about the Bosch O2 sensor. They swear it’s the right one but it seems too short, doesn’t reach into the exhaust stream like the Denso did.... thanks

 

You really can't trust 'them' or 'they' or their opinion as they don't love our tacos like we do. Trust the collective here on the forum. Many guys on here with decades of detailed experience with Toyota trucks and 4x4s.
A shop that swore to me that a Bosch A/F sensor is correct on my Yota wouldn't be getting anymore business from me.... If I used shops I would put the correct Denso sensor in, but that's me

 

I would swap it out for a Denso, Toyotas don't have good history with working well with other brand sensors

 

if you check the "pending" portion of the scan tool Ill bet that that code is ready to pop on the CEL... it hasnt meat all of the parameters to set the code yet.

 

For the archives... good riddance

 

Damn, the manifolds on the 2UZ-FE on the 100 series Cruiser were known to develop a hairline crack and then that annoying tap when cold until it closed off when heated.
I don't know that they affected performance much though? (long time, don't remember though)
So you thinking that split could've been affecting that much? I guess it's definitely plausible

 

Whether cracked manifold or faulty sensor, best to have them both replaced at the same time. Might want to go ahead and clean the injectors while at it.

 

My 95 2.7L was cracked all the way around when I replaced it. Honestly though, as far as I could tell, it was not affecting the performance. I could hear it leaking, but didn't notice any change after replacing it.

I went with a cheap Rock Auto replacement, so maybe next time it cracks... , I'll see a difference.

 

I'm paranoid to all get out with those cracks! I've had two pre '00 3rz with the cast manifold now, and both developed cracks in the cyl head.

I strongly recommend getting a leak down test done on each cylinder!

 

So are you saying you think the cast manifold contributed to the head cracking? Just curious, got a 3RZ too.

 

In my very limited experience? Yes I do whole heartedly believe that. On both my motors the cyl directly in line with the crack on the manifold turned out to be cracked, and both were cracked in between the 2 exhaust valves

 

extra oxygen in the exhaust port makes it run much hotter locally.