Mr.WS6

hey guy's i need some help with this code! PO174 in the obd2 scanner it shows as a bank 1 system to lean, also bank 2 system to lean.. i have pretty much all the bolt ons in my trans am. i also added the o2 simulaters from casper electronics. i changed both oxygen sensors just to be sure but the code poped up again. i pump nothing else but 91 octane. and i get real bad gas mileage i get 200 miles to the whole entire tank. so if you guy's could help me out here....

horist

sounds like a vacuum leak ... unmetered air is entering the system... PCM tries to correct but can't add enough fuel ... the codes you're getting put you in Open Loop which will cause very poor fuel economy on a car not tuned to run open loop full time

Mr.WS6

[B]so it needs a real bad tunning... i should take it to dyno tunning shop so it could get checked out. and get it tune... thanks for the info.

horist

No... if it is a vacuum leak you need to find out where the unmetered air is coming from

Mr.WS6

what area should i look at or start to look?

horist

what have you changed recently?

Mr.WS6

the only thing ive done is put the catch can. but the problem was already. oh my throttle body is gasket is leaking. i also ported my mass air flow sensor.

horist

ported MAF can cause incorrect readings causing the PCM to command more fuel... also a leaky throttle body gasket will cause a vacuum leak (unmetered air entering the engine)

if the catch-can isn't a sealed system (any leaks) it can also cause a vacuum leak

ChrisS@sdpc

You can get a full description of the problem and diagnostic steps here. If any air is entering the system after the MAF, then it can cause you problems.

Mr.WS6

i think i fixed the problem because the code hasnt came back. when i put my catch can i didnt put hose clamps on the hoses so it was probably leaking from the crackcase ventalation. but as far as the poor gas mileage what should i do. i still get 200 miles towards the tank.. any ideas you guy's been a good help.