left o2 seneor lean cant find manual ,help

[bradslt5]

car felt a little funny yesterday , scanned and found left o2 sensor lean ,still cant find my manual (effects of moving). what do i look for?. the car has 40k original miles so i am wondering if it might be injector time

[Paul Workman]

car felt a little funny yesterday , scanned and found left o2 sensor lean ,still cant find my manual (effects of moving). what do i look for?. the car has 40k original miles so i am wondering if it might be injector time

A sensor can be telling you the truth, or not. In either case there is additional evidence present to either support or dispute the sensor.

If the sensor is correct, then there is a fuel delivery problem on that one side of the engine; one or all injectors involved. Just one injector being bad I don't think would give you a lean reading - it might run rough or not idle smooth, but it is unlikely all the injectors on a given side crapped at the same time.

On the other hand, when O2s go bad, I can't remember a time when they indicated rich: they to a single one indicated lean. And, the ECM always responded by riching up the fuel delivery to that side of the engine. The give-away is the rotten egg smell from the affected side cat. (The instant fuel mpg, drops from around 26-28 to around 17 on an LT1 with a bad (reading lean) O2, and I imagine the LT5 would do about the same.)

Just a couple thoughts

P.

[bradslt5]

my o2s are brand new , i guess they can go bad , thought i might get a few more ideas on whats wrong , oh well paul thank you so much for your thoughts

[tomtom72]

Brad, if the fuel #'s for that bank are saying rich but the O2's cross counts are saying lean then it proly is the injector coils. That's what I found when my coils crapped out on the scan tool.

I was a noob( I'm still not fluent in EFI ) & didn't realize that the data I was looking at was seemingly contradicting what my nose was saying....dead lean smell out the exhaust and the data presented the opposite picture because I didn't realize that the data is from the ECM's point of view. That is to say if the injectors go lean, the ECM only knows to go rich on the fuel #'s because it has no direct link to monitor the functioning of the injectors...but the results still show a lean condition on the O2 sensor because that is the feed back side of the loop. The fuel #'s are the control side of the loop.

After all that BS, yea you might want to ohm out the coils or switch O2's side to side & see if the condition follows the sensor, or just pull some plugs on the lean side & have a look??

:cheers:
Tom

[bradslt5]

thanx so much for the post it really helped .now to just find some time to do it..