wdornbach

99 maxima, CA spec. Yes, I searched but could not find this answer.

What is the left and right side of our engines?

I got an SEL PO420 (0702) Bank 1

Ok so I know where bank 1 is, that's easy as shown in the diagram in this thread:

https://maxima.org/forums/4th-genera...-location.html

BUT Is bank 1 the left side of the engine? or the right side? Searching for the 02 sensor on Rockauto shows only "downstream left, or upstream right etc. The don't show it as upstream bank 1. SOOOOOOO what is left and right? If I'm standing looking at the the drivers side of the car, I'm facing the transmission, which is right or left? Is the radiator the right side or left side? SOOOOO coffusing.

Thanks!

saig

Front of engine is where the flywheel is located. Standing on the left fender side looking toward the engine's flywheel, left is radiator side, right is firewall side. If the ignition firing sequence is 1 2 3 4 5 6. Bank 1 is where the first cylinder at. Bank 1 is firewall side. Bank 2 is radiator side. Other car manufacturers use different arrangement of cylinders in V engine. If they are grouped as 123, 456, compare to 135, 246 in the Maxima, then they MUST use left or right to describe the banks correctly.

Upstream O2 sensor is for detecting if the combustion (detonation) is stoichiometric burn, i.e. no more unburnt gas in the exhaust fumes. These sensors are located as close as possible to where the exhaust gas exiting the cylinder. Therefore it is called upstream. These sensors are sometimes referred as Air/Fuel AF ratio sensors. Their principle of working is they have heating element. If the heating element is burning, you are running rich. If the element drops temperature, you are running lean. That is why you may see HO2 that is abbreviated for Heated.

Downstream O2 is for detecting any remaining unburnt gas after passing catalytic converter. For 99 CA specs, Nissan engineers may have tried to use engine heat to help precat burn majority of the leftover, improving/meeting the stricter emission requirement.

Correction: I was mixed up on the heating element. I want to edit it here without changing the orig. message. The material used to detect oxygen needs to be at high temperature. The heating element is for heating up the sensor to working temperature. Cat. convert burns any leftover.

wdornbach

Thanks saig! Outstanding detailed response. Much appreciated!

saig

Same here. Your recent update to PS Pump Replacement Sticky is excellent. I'll plan tackle that job this summer.
Cheer!

wdornbach

Thanks! Glad you like. I actually just updated and added a few more details to that PS pump replace thread.

If you like that one, check out my rear main oil seal replace procedure: https://maxima.org/forums/4th-genera...procedure.html

If I get time I may do a clutch R&R procedure. Recently installed a south bend stage II clutch, it is absolutely freaking awesome. Super soft pedal but killer holding power and zero chatter!

KP11520

Hey WD,

If you replace one O2 sensor, just replace all of them. These cars are old enough and the sensors certainly drift a bit than when new. O2 sensors help control fuel mix and when new, CA spec 99s run better. Just did mine with an all new CARB compliant exhaust past the exhaust manifolds. Stupid money.

But I used NTK O2 sensors on ebay (for best price for each of the 4 delivered) and it was quite reasonable (as low as $26)..NTK are the manufacturers of the original OEM installed when new.

Enjoy the ride!

wdornbach

Good point KP, thanks for suggesting. By chance, I have the one I need in stock & it's an NTK. (Agree, I always buy NTK sensors and NGK Plugs).
I'll surf the net to look for the other 3!