(Honda Civic) Excessive Short Term Fuel Trims at Higher RPMS

2015 Honda Civic LX 1.8L

[@chrisisho2557]

I have positive High LTFT & STFT, LTFT %26 and STFT 18%, STFT increasing with high RPM and LTFT degrees with High RPM but not gose less than %18 whatever RPM, Example, LTFT %26 and Change to 18% once touch accelerate paddle and stuck at %18 even if 6000 RPM, I made smoke test but no leak at all Replaced Valve cover including low pressure fuel pump with filter Also changed intake gasket but still same symptoms, Last thing replaced Bank1 sensor 1 O2 sensor, You think bank1 sensor 2 O2 sensor causing high fuel term or something else ?

[@EliTheOBDTech]

@@chrisisho2557 Did you smoke test the brake booster? Is your current vehicle a Honda? If yes, you may need a valve lash adjustment.

[@chrisisho2557]

@@EliTheOBDTech I have C250 and break booster has separate vacuum pump and not connect to intake hose, you think vacuum leak or fuel delivery issue ?

[@EliTheOBDTech]

@@chrisisho2557 From your fuel trims, it aims vacuum leak, but also fuel delivery can be a possibility, such as dirty injectors.

[@chrisisho2557]

@EliTheOBDTech thank you so much, I'll order injector cleaner and see if something changes, thanks again for sharing your experience 😊 ☺️

[@AT_Eng]

why are you reading the data pids in generic mode ?

[@EliTheOBDTech]

@@AT_Eng In generic mode, you are able read fuel trim numbers much better than in enhanced mode.

[@SoufyanAbdalla]

Is it possible to preform the test using thindiage operating on diagezone pro v2

[@EliTheOBDTech]

I'm not familiar with that device.

[@Elprofesor997]

Hi please give me an advice because im having headache with my car i have audi A5 TFs 1.8 and long term fuel trim stays at 0 but the short fuel trim goes negative -25 I can't really understand i have changed camshaft sensor air intake sensor the maf works fine thank you

[@EliTheOBDTech]

Have you checked for vacuum leaks?

[@EliTheOBDTech]

Is your car direct injection? If yes, maybe a mis-reporting high fuel pressure sensor or leaking high pressure fuel pump.

[@Chevy-f4l]

​@@EliTheOBDTech I have a 08 Chevy Express with a 6.0 vortec I have p0300 p0171 p0174y short term trims on bank 1 are at like +3-5 % at idle and LTFT are at like +17 Bank 2 short term trims are at +3+5% ltfy at +24% when I accelerate the stft go up to (24 om bank 2 and aboit 17 bank 1 and 24 on bank 2 i check fiel pressure and put a vacuum tester and both were good...any advice

[@EliTheOBDTech]

@@Chevy-f4l These engines are notorious for intake manifold gasket leaks. Dirty MAF sensor can also cause these fuel trims numbers.

[@luisduque4506]

I had the same problem but after I replace the intake hose my fuel trims are the same ,short is +46 😮, not more leaks ,I tested it with a smoke machine ,I don’t know where it go from here 🤷‍♂️

[@EliTheOBDTech]

How is your long term fuel trim looking?

[@EliTheOBDTech]

Did you check your brake booster for vacuum leak?

[@luisduque4506]

@@EliTheOBDTech 18 all the time

[@luisduque4506]

@@EliTheOBDTech I check the line going in ,I am goin to take a look