2 bad oxygen sensors affect performance?
 

Had cnt test pipes installed and they ended up using impact wrenches which definitely made one 02 sensor go bad, and possibly the other. My question is, will this affect performance in any way?

From the FSM (G37 version):

The heated oxygen sensor 2, after three way catalyst 1, monitors the
oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the signal
from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates voltage
from approximately 1V in richer conditions to 0V in leaner conditions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.

thank you for the post, but my question is, what are "normal driving conditions?" Is this affected during wot?

And that quote is only referring to one of the sensors. i.e. "Oxygen sensor 2"


http://www.autohausaz.com/html/emiss...n_sensors.html

Oxygen sensor 2 refers to both O2 sensors that plug into the cat (i.e. Oxygen sensor 2 Bank 1 and Oxygen Sensor 2 Bank 2). The ones that measure A/F (prior to the cats and plug into the exhaust manifold I believe) are called A/F sensor 1 Bank 1 and A/F sensor 1 Bank 2.

As for what constitutes normal conditions, not really sure but I would guess that refers to the A/F sensors being operational.

My question is does the computer open up a different set map at WOT and go into open loop without making corrections using the o2 sensors but the maf sensor instead?

When people get the check engine light from installing test pipes and high flow cats, I am told it does not affect performance. Fuel economy sure, but will the computer accept the modification and run properly at WOT?

By the way, please answer in simple terms as I do not understand much of the information mentioned about the o2 sensors in previous posts. It seems like you are giving me answers based of a manual that does not really account for situations like this. Plus it doesn't really tell me anything to know which sensor is which and does what, if it operates differently with the cel on.

I worked on attack helicopters in the military and from experience, nothing relating to fixing or troubleshooting the birds was in the book. It was all trial and error, and learned by test flights and seeing results. I figured since so many people have the cel when the install test pipes, there would be plenty of info regarding whether or not the car will perform properly with the cel on.

There is just a vague answer of no it does not affect performance with no real basis or mechanical proof to back it up.

The shop I am going to is fantastic and took full responsibility for replacing the sensors. The name is Genesis Racing Development. The guys spent hours working on the demon bolt only to find out both sensors were destroyed during the melee. This is an extremely stand up shop as most would have given me the car back and said its fine. They wouldn't even let me leave before test driving it for safety, and ordering the new sensors.

I am very grateful to have found a great shop in Chicago

You haven't said which sensors are suspected as bad? You will most definitely get a code with test pipes for the 2 post cat sensors, these sensors are not used in fuel mix calculations, merely to monitor cat performance. The 2 pre-cat sensors are wide band and monitor the fuel mix, although under WOT you should be in open loop. You can also get a performance code warning for the O2 sensor if the gasket does not seal or blows out.

That is a good question. I assumed the bad sensors were the ones that install directly into the cat since that is what they replaced. I do not know the location of the other sensors to figure out if they were the ones that went bad.

The mechanic did mention the computer does use readings from these sensors to make corrections, but I assumed they were the same sensors that throw cel in other test pipe driven 370z's.

It very well could be a different sensor location, I assumed removing the cat, cat sensor destroyed.

From what I have read, the common code p0420 of cat efficiency low is normal and can be ignored. Since I don't even know the code I am throwing, and they deemed the sensors bad, I will just wait to have them installed and see what happens.

The sensors in the cat are not used for anything except cat efficiency testing (comparing the delta in O2 readings against the upstream). An efficiency code is expected in this case with test pipes (UpRev tune can delete these codes). If it is a different code you should let us know, I got a code for the upstream sensor (the real O2 sensor) when I blew out my exhaust flange gaskets where the header meets the test pipe. The real O2 sensor is installed in the bottom of the factory header.

great, thank you for the info. I appreciate it and now I understand how the system works. I do plan on uprev tuning in the future, just wanted to have the knowledge to make good decisions.