MPG drop since tuning

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9thGenBestGen
Posts: 1
Joined: Tue Aug 04, 2020 5:08 pm

MPG drop since tuning

Post by 9thGenBestGen »

Hey guys, I bought KTuner v1.2 a couple of weeks ago and have been playing around with it a bit. I've heard great things about the software and love it thus far.

My car is a 2013 Civic SI with a KTuned 3" intake and stock otherwise. I see you guys post a lot saying there are no aftermarket intakes that work with the factory MAF and I get that, but I love the noise of the intake too much to go back to stock. I've been 'street' tuning with a friend at work who has a lot more knowledge on the subject than me. We've been tuning the base map that's on the software to run lean in cruising/low throttle in an attempt to get better gas mileage overall (we have not started playing with the MAF scaling yet) I'm currently averaging (according to the car's gauge) 30-32mpgs which is way lower than I've gotten with the stock tune (34-38). It doesn't make sense because everything we've touched has been leaned out and even the STFT is showing a lower percentage than the stock tune, yet the car is sucking fuel. The only other thing that has changed since running the stock tune is I've added an intake tube that sits next to the driver fog light and channels colder air straight to the intake filter. My IATs are around 17-20* above ambient because of the tube, as opposed to 30-40* above ambient without it.

Our theories so far
- the IATs are lower, causing the ECU to throw more fuel at the car
- the gauge in the car is inaccurate because it's used to seeing the stock ECU values and bases it's information on that
- something is wrong with our tuning.

My next step is to throw the stock tune back on the car to see if I still get bad MPGs, which would eliminate our tune being at fault. Do you guys have any other recommendations on what I could try and change in the tune or with the setup?

I appreciate your time and your response.
KTuner
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Posts: 3050
Joined: Mon Jul 22, 2013 8:13 pm

Re: MPG drop since tuning

Post by KTuner »

If you're getting more air you'll be using more fuel. Beyond that it is directly depicted by your foot on the gas pedal.

You shouldn't be messing with AFR targets until you've fixed the MAF curve for that intake.
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