I have noticed the long and short term fuel trim is around -10% ... i've run BG Platinum® 44K cleaner through twice ... doesnt help
I've cleaned the MAF (even replaced it with the OEM Hitachi part, made 0 difference)
New battery / no vacuum leaks
Any ideas?
2011 Honda Civic 1.8l petrol hatchback automatic
How's it running? Take air filter out and re-check (obviously not in a driving/dusty environment). Also check TPS (manual should give values). Check fuel pressure to see if it's too high (this would be unusual but...).
How many miles? How did you discover it? Did it slowly start running bad and you checked and at -10%, or did you monitor/notice it going more and more negative over time? You might not know the answers to these questions but was it running good one day/moment and then bad the next? Or did you notice it starting to run bad over time? Heck, is it even running bad?
Just been serviced, new oil/oil filter/ air filter etc)
Fuel pressure is normal
185000kms
I noticed it when plugging in a new ODB2 took i bought, honestly, i don't notice it perse but i feel negative 10% isnt an ideal figure long term
Yea, not ideal at all, I like to see under 4 but does vary per vehicle. Cars usually start throwing codes at around 12 (varies by manufacture). I'd still try without air filter as it should decrease because the pcm is currently removing fuel (usually it's the other way around due to vacuum leaks). Just noticed I missed something, when LTFT stabilizes at -10% does STFT stay at -10% too? This shouldn't be happening as STFT adjusts long term until STFT reaches 0... if it doesn't get to 0 STFT under a constant and consistent load, LTFT should still be decreasing until it does, .... maybe I'm misreading that in your post..
Have you verified it's going into closed loop operation after warm up?
@hillbilly
short term is all over the place ... between -1 and -11 ...
i'll try remove the air filter later and see what happens