negative LTFT both banks -13,-14 constant ?

[jaimster]

hello guys ,


So I have been dealing with vacuum leaks for a while LTFT high both -/+ so i TOOK care of the following items :
(vacuum system re-done al fixed ) , leaky AOS (replaced now ), new FPR , new upstream 02 sensors both banks , new spark plugs , new MAF sensor , bank 1 intake gaskets replaced , oil fill tube replaced
several smoke test - last test no more leaks as of now.

I m down to the "evap purge valve" - read somewhere that maybe staying open causing air/fuel mixture issues !!!!!

last night got my car running after a while seems to idle and run pretty good however bank 1 LTFT - 13 bank 2 LTFT -14 WTF....

both banks upstream sensor voltage fluctuating pretty good , I m afraid soon or later MIL will come back and emission components 2 of still not completed test so waiting for them to be completed so I can the inspection..

help a brother out here what else ?

[The Radium King]

what tool are you using to get the data? using a porsche tool you should get two readings:

FRA which is the closed-loop load value and is a number that can be between 0.7 and 1.32 before you get a code.

RKAT which is the idle value and can be between +/-4% before code.

vacuum leaks will usually impact idle before load as the small amount of air has a bigger impact when idling than when at load sucking in a lot of air.

load trim issues are often due to fuelling.

bad sensors (o2, maf) can get you too.

[The Radium King]

... and did you disconnect the battery to reset the trims after doing the work? otherwise they will hang around a while.

[jaimster]

i got that data using ICarsoft PORIII

although I also have durometric which I can also pull the data using it .

MAF sensor and 02 new ones too .

also before the last rive cycle I had deleted the MIL since then I have completed 7 components for the emission test - hate to reset everything and start getting it ready again.!!!!

planning to take it for smog test / emission test here in TX in about an hour or so is past due two months now.

[Lowski]

Years ago when dealing with a bad MAF sensor I saw something that may be similar. I replaced the MAF, cleared the codes and fired up the car while watching the Durametric fuel trims. To my horror they were out of range. I thought I wasted a bunch of money. It took many minutes of running at idle for them to settle out and the engine to run smoother.

The lesson I learned, is anytime after to clearing the codes let the car idle for a while before driving it. I'm not sure what your timeline looks like, but this is something to consider.

[jaimster]

Originally Posted by Lowski

Years ago when dealing with a bad MAF sensor I saw something that may be similar. I replaced the MAF, cleared the codes and fired up the car while watching the Durametric fuel trims. To my horror they were out of range. I thought I wasted a bunch of money. It took many minutes of running at idle for them to settle out and the engine to run smoother.

The lesson I learned, is anytime after to clearing the codes let the car idle for a while before driving it. I'm not sure what your timeline looks like, but this is something to consider.

I did DO that let it idle for a while several times, fuel trims specially LT were pretty good till I drove back and forth to work and the gym - I have also noticed at increase speed higher RPMs LTFT are as high as -17 on Bank 2 and bank 1 -15 ALWAYS banks around 2 % points difference.

I m thinking there may be a chance on the 02 sensors not reading right perhaps !! so swapping the upstreams sensors from bank1 to bank2 really curious if BANK 2 MAY STILL BE HIGHER OR NOT

AND also just got the evap purge valve - replacing bank 1 intake gaskets since that has to be removed anyways to get to the valve .