SES light on

[Zkid14]

SES light came on the other day so i brought it in my shop and hooked up the scanner. told me bank one and bank two are running lean. Now i looked for vacuum leaks (didnt find any), checked the mass air flow sensor (cleaned it too) and tried to spot check the o2 sensor wires, so besides it being falty 02's what else would be tripping this code? any help would be appreaciated


also my dash board randomly cracked on the top plastic panal piece, any reason for that? i didnt hit it with anything or give it any reason to crack that i know of.


Matt

[BAD LS1]

There could be several reasons causing the P0171 lean code...

typically u need a radical change in engine operation like a cam or long tube headers etc...

The root cause is typically unmetered air getting in behind the maf somewhere, or the screen has been removed which can cause it to go baserk.

most lean codes can be set by the post cat o2 sensors that have a leak ahead or behind that will allow fresh air to be drawn in and mess with with the readings making the computer adj the long term fuel trim more than 25% to get it back within check.

Something had to have changed drastically in your set up, like a new part or something didnt get tightend to make the long term fuel trims to go way positive all of a sudden...

[Zkid14]

so what would you suggest I do? I hopefully will be putting in new headers soon and then putting in 02 sims, wait till then to see if there was a leak there and that was the problem? or is there something else i can do to try to fix this? I've looked over the engine pretty well for vacuum leaks and still have come up with nothing

-Matt

[BAD LS1]

Well i dont know thats the thing... im not there to inspect my self but something has been changed or is causing it as of recently....

Is your maf screen out?, Did you put the maf on backwards?, is the clamp tight where the t body meets the bellows?, Are there any tears in the bellows?

This condition just doesnt happen on its own...

[animal]

Though I know nothing 'bout fbods, some guys put Valve cover breather caps on the fords and they'll get a lean code that way too.

[BAD LS1]

Though I know nothing 'bout fbods, some guys put Valve cover breather caps on the fords and they'll get a lean code that way too.


Yeah i heard of that before not just on Fords... it allows fresh air to get sucked in through the PCV system and then straight into the intake it goes and leans it out due to un-metered air.

[Zkid14]

well....yes all that stuff is tight and driving down 59 yesterday the light went off :wtf so anyone else's guess is as good as mine

-Matt