Cliffburton99

What could cause my long term fuel trim bank 2 to be up at around +17% and short term stay close to 0 and both on bank 1 stay close to zero also? possibly bad inject0rs on bank 2 side? Help is greatly appreciated.

bobdec

Short term trims are set every so many milliseconds, so they are what's happening at that time. The ST trims update the LT trims every so many seconds , but remember the LT trims are an average of the short terms since the PCM has been powered up for an extended period. If you have a problem coming and going, or you have worked on the engine it's good practice to reset the PCM (pull battery negative cable or PCM fuse) so the LT trims start out fresh at 128 without averaging in any old readings. As far as +17% on bank 2 (right passenger side) could be anything, O2 reading incorrect, injector, manifold gasket , mechanical . Check for intake or header (exaust manifold) leaks, you can swap the O2's left to right to see if it moves, you can swap injectors left to right, etc. A data scan could help.. I assume you are OBD2, what year and model

MikeGyver

Once the 17% long term fueling correction has been established, the short terms are then centered or "learned" (because of the correction), so they'll be around zero.

If for example your short terms are at 15%, they will slowly adjust the long term correction until the short terms are zero; the fueling correction is then "learned".

If you have a long term split between banks then it might be a fuel injector or O2 sensor problem.

Cliffburton99

The car is an all stock z28. That would make it obd2.

Airbornec507

94-95 are OBDI

96-97 are OBDII

What year is yours?

Doc87IROCZ

To determine whether its an O2 problem or not, switch the front two O2 sensors with each other, and see if the +17% LFTF follows with the O2 sensor or not. Its one trick that I've learned.

EDIT: I am thinking he has a 1999 car, so its an OBDII system.

Injuneer

Maybe he has a 99 based on his screen name - who knows????

Cliff - ADD A SIGNATURE with basic info about your car - year, model, engine, trans and any major mods. That way people cab help you without guessing.