TheMustangLoveR

Isn't that backwards?

moosestang

It's not backwards if the motor isn't really running lean. The o2 sensor just senses oxygen, that oxygen could be from an exhaust leak before the sensor or I assume that incomplete combustion would raise the oxygen content of the exhaust. The 02 sensor see to much oxygen, so it increase fuel. The engine may not need that fuel if the sensor is bad.

moosestang

Well my problem turned out to be a bad COP. I had accel cops for the past year and putting the stockers back on fixed it.

My spark plugs for bank 2 looked like this.

sinister99GT

i just put a kenne bell on my 99 gt, i also have a lean bank 2 code. the car runs great, makes killer hp and torque. i have been hunting this problem since christmas. i just switched my rear o2 censors today to see if it throws a bank 1 code, if no change i will switch the fronts.

WhiteFoxGT

Just because the 02s are throwing codes, does not mean they are bad! 02s are simply doing their job, and everyone comdemns them right off the bat. There is air leaking into/out of the motor some how. Check vigorously for intake leaks and exhaust leaks. I'd be willing to bet thats the most common culprit

moosestang

Well in my case air was leaking out of the cylinder that wasn't firing correctly. I'm surprised it didn't set a different code like a misfire. I agree that the 02's are not usually the problem, but the easiest thing to blame.

For the 99 gt with the KB, maybe it's the tune or your fuel system isn't up to the task at hand. Pull your plugs first. You may even have some that are loose, letting air get in.

sinister99GT

the car runs great though, i have checked for vacuum leaks and have none.the last time the cel came on was two weeks ago today.i have been gettin on it to get the boost up so i get some wot time to try to trip it.i dont belive it will come on in a normal driving siguation, only in boost. its been cold in florida since i have put the supercharger on, dont know if the air temp could be part of it.i am new to the supercharger stuff , trying to learn as i go.on the dyno my a/f ratio was 12.2kenne bells tune is programed at 11.8.any opnion on what might cause the differance would be apppreciated. its a 99 with 105.000 miles on it.

WhiteFoxGT

What mods do you have as far as fuel management. And was the car dyno'd on the KB tune or was it custom tuned?

sinister99GT

it has the kenne bell boost a pump and the 36# injectors that came with the kit. the tune is from kenne bell, its a chip not a tuner. the a/f for the three runs on the dyno were consistent,12.2,12.3,12.2.other than the exuast there isnt anything else done, they wanted everything back to stock. took off the cai, took out the diablo tune.it idles is perfect, runs awesome, there are a couple of speed shops on the other coast of florida that kenne bell is comfortable with, if it continues i will end up spending a weekend over there . i like the paint on the truck, if you get a chance take a look in my garage. i have some custom paint done also.

BrittanyJean

I realize this thread is 12 years old and that you might not even be on here anymore, but THANK YOU for this comment lol. I’ve been driving with cracked exhaust manifolds for probably about 3 years now, so when it finally threw the p0174 code, I pretty much knew what the problem was. But I came to the forum because my floorboards and center console started getting really hot, so I thought maybe there was a bigger issue at hand (like maybe I finally clogged the cat or something).. and ALL I’m seeing is “change the o2 sensors” (or clean the MAF sensor. Those were the top two for sure). Like, It’s a sensor.. it’s sensing the issue. You gotta try to find the issue first, THEN blame the sensor! I just found it funny lol, so thank you for being the one to point it out.