Short term fuel trim shows -9% (Rich)

Question

Honda Civic 2007 90km odometer
Problem-
Fuel consumption
I have scanned my car and it shows STFT -9% along with below parameters.

Coolant temp -> 64
LTFT -> -7.03
Oxygen sensor voltage -> .55v
EGR Error -> 99 %
Commandent EGR Duty -> 0%
Commandent evaportaive purge -> 22%
MAF flow rate - 2.7g/sec

I understand that if STFT is in negative then this is rich condition and it can impact fuel consumption widely. and the cause could be leak, fuel injector issue etc.

Any insights why my vehicle is not up to mart for mileage(fuel consumption)
Pls let me know if I need to share more data about this.

Captain Kenpachi · Answer

You most probably have a leak in your intake system AFTER your MAF sensor. So your MAF sensor reads that you're getting x amount of air, but more is sucked in (or is lost if you have a turbo and it is currently boosting), so you're running slightly richer than you should be. Your ECU sees you're running rich, and adjusts the amount of fuel using the fuel trim.

Answered by Captain Kenpachi on December 14, 2020

Short term fuel trim shows -9% (Rich)

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