running lean?
Thread Starter
Staging Lane
Joined: May 2009
Posts: 56
Likes: 0
running lean? ok so i was driving my car and gave it a bit of throttle then backed off(didnt go WOT) as soon as i did that, i got an ses light. I took the car home and it felt like it was misfiring. I used the scanner and the codes said banks 1 and 2 were too lean, and it also threw a code for the front o2 sensors. My question is, can the o2 sensors cause my car to run lean? and when a car runs lean does it feel like a misfire? thanks for the help.
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
Yeah, could be a lot of things. If 171 and 174 are set at the same time could be a fuel issue, vacuum or PCV leak.....
www.gearchatter.com/viewtopic8737.php
www.gearchatter.com/viewtopic8737.php
Launching!
Joined: Sep 2009
Posts: 236
Likes: 0
Bad 02 sensors will not cause misfiring... most likely it is NOT the 02s... expecially if you have a lean code, the sensors are just related because they are reading lean as well. try cleaning your maf with "MAF cleaner" only, dont use brake clean or anything else. then clear the codes... that should take care of it, otherwise a fuel issue... OR find a shop who does free estimates... I know youd be wasting there time, but hell, if its free..... I do it all day long for people...
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Thread Starter
Staging Lane
Joined: May 2009
Posts: 56
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thanks guys. I haven't done any mods to it. I changed the o2 sensors and it started running better, but once I got to WOT the ses came back on, and sure enough, it was running bad again. the code it threw now is po174 and the o2 sensors as well. I just bought some MAF cleaner. I hope it works.
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Verdad Gallardo Thread Starter
Staging Lane
Joined: May 2009
Posts: 56
Likes: 0
Well...I cleaned the MAF and it didnt solve the problem, its still running just as bad as before, except now the only codes it throws are for the o2 sensors 
I'm getting fed up with this car, I cant even enjoy it.
I'm getting fed up with this car, I cant even enjoy it. 
Staging Lane
Joined: Feb 2008
Posts: 83
Likes: 0
dont get too fed up with it just yet....wait till you start to do mods and then things are not right haha thats when you get fed up with them!! Are there any other codes esides just the 02 codes?? and did you replace the 02s with a gm relpacement or a cheap one??
Teching In
Joined: Nov 2007
Posts: 23
Likes: 0
i also randomly get the p0171 and p0174 lean codes. but the car still runs fine even when the light is on. usually i drive a few miles and it goes off on its own. i have cleaned the maf and that didn't work for me. i think i'm just gonna have to find a shop that knows what they're doing and see if i've got a vacuum leak somewhere.
Thread Starter
Staging Lane
Joined: May 2009
Posts: 56
Likes: 0
now its just throwing the o2 codes, and i used the bosch o2's. this morning i turned the car on and it was still shaking and all that, but then the idle got really low and wanted to die(i gave it throttle and kept it from dying) later on i turned it on again, and the idle wouldn't go as low, however when i would give it gas, it would sputter and as i would let go of the throttle I could hear small explosions, detonation maybe, backfire? I'm gonna check the spark plugs even though they a long with the wires are new, but I will probably end up taking it to a shop.
Did you even go read the procedure for the codes?
Did it start after a fuel fill up?
How old is the fuel filter?
Did you check to see if perhaps a vacuum line came off near the TB?
Some very basic items. They make diagnostic tables for a reason. Guessing and tossing parts at it just helps out the economy and won't fix your car.
Did it start after a fuel fill up?
How old is the fuel filter?
Did you check to see if perhaps a vacuum line came off near the TB?
Some very basic items. They make diagnostic tables for a reason. Guessing and tossing parts at it just helps out the economy and won't fix your car.
