Decreased mpg after catless downpipe?

[suhhh]

Installed my catless DP on Friday and ever since then I've noticed that I'm going through my tank a lot quicker. I definitely do have a bit more heavier foot after installing it because of the quicker turbo spool but after filling a fresh tank today I can only get max 30mpg by driving fairly soft with sport mode off, used to get around 32-34 mpg before with pretty spirited driving. Also for whatever reason my gas indicator wouldn't fill all the way up even though the gas attendant swore it was full (could just be it wasnt full but not sure if it's an issue). Should a catless DP cause this much mpg decrease? I'm also untuned so not sure if Ktuner will be a fix. This is my first time installing and using a catless dp so I'm just unsure, just hoping it's not something I messed up while installing it with a buddy

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[N-Kryptic]

Installed my catless DP on Friday and ever since then I've noticed that I'm going through my tank a lot quicker. I definitely do have a bit more heavier foot after installing it because of the quicker turbo spool but after filling a fresh tank today I can only get max 30mpg by driving fairly soft with sport mode off, used to get around 32-34 mpg before with pretty spirited driving. Also for whatever reason my gas indicator wouldn't fill all the way up even though the gas attendant swore it was full (could just be it wasnt full but not sure if it's an issue). Should a catless DP cause this much mpg decrease? I'm also untuned so not sure if Ktuner will be a fix. This is my first time installing and using a catless dp so I'm just unsure, just hoping it's not something I messed up while installing it with a buddy

Since it's catless and not tuned I assume you have a rear o2 spacer installed for the CEL? Even though it's the rear o2 it can still throw off long term fuel trims and cause an increase in fuel consumption, as well as due to the turbo spooling quicker the ecu is adding more fuel all the time even if you aren't flooring it. Also your right foot has the biggest impact on fuel economy, I suggest to look into either flashpro or ktuner especially with a downpipe.

 

[suhhh]

Since it's catless and not tuned I assume you have a rear o2 spacer installed for the CEL? Even though it's the rear o2 it can still throw off long term fuel trims and cause an increase in fuel consumption, as well as due to the turbo spooling quicker the ecu is adding more fuel all the time even if you aren't flooring it. Also your right foot has the biggest impact on fuel economy, I suggest to look into either flashpro or ktuner especially with a downpipe.

Nope no o2 spacer, running it with a CEL right now. And okay gotcha, I figured it was definitely more increased gas consumption simply because of the turbo spooling a lot quicker, I guess I have to be a lot more mindful of my foot.

If I drive with the same exact driving habits, will I get an increase in mpg after tuning it?

 

[amirza786]

As mentioned above, it's recommended to get a tune with a DP, especially Catless because you are throwing things off and your fuel trims could be off. Also this car is extremely efficient until you go hard on it, and we tend to go harder on it once we tune it for more power. Engineering Explained does a video on this where he shows how smaller efficient engines that have been turbocharged for more power are not as efficient when we go hard on them for more power (the video is labeled "Why small Turbo Engines are not Efficient")

 

[N-Kryptic]

Nope no o2 spacer, running it with a CEL right now. And okay gotcha, I figured it was definitely more increased gas consumption simply because of the turbo spooling a lot quicker, I guess I have to be a lot more mindful of my foot.

If I drive with the same exact driving habits, will I get an increase in mpg after tuning it?

As mentioned above, it's recommended to get a tune with a DP, especially Catless because you are throwing things off and your fuel trims could be off. Also this car is extremely efficient until you go hard on it, and we tend to go harder on it once we tune it for more power. Engineering Explained does a video on this where he shows how smaller efficient engines that have been turbocharged for more power are not as efficient when we go hard on them for more power (the video is labeled "Why small Turbo Engines are not Efficient")

This^ Also when running a downpipe you will want to use a tuner platform to utilize boost by gear to limit low end torque so you reduce the likelihood of bottom end failure. It's recommended to either get a canned tune that has the proper config for your specific downpipe, but there aren't many options when it comes to that so the best is to go to a reputable tuner and get a custom tune done.

 

[suhhh]

As mentioned above, it's recommended to get a tune with a DP, especially Catless because you are throwing things off and your fuel trims could be off. Also this car is extremely efficient until you go hard on it, and we tend to go harder on it once we tune it for more power. Engineering Explained does a video on this where he shows how smaller efficient engines that have been turbocharged for more power are not as efficient when we go hard on them for more power (the video is labeled "Why small Turbo Engines are not Efficient")

This^ Also when running a downpipe you will want to use a tuner platform to utilize boost by gear to limit low end torque so you reduce the likelihood of bottom end failure. It's recommended to either get a canned tune that has the proper config for your specific downpipe, but there aren't many options when it comes to that so the best is to go to a reputable tuner and get a custom tune done.

Thank you both! Would it necessarily be bad if I kept running DP without tune for a few months? I was planning on getting ktuner a little later, but if it's going to be bad for my car and cause issues running it without a tune I might just get it earlier

I also definitely noticed that I can get decent mpg if I just drive conservative but as soon as I start banging gears and flooring it my mpg goes out the ass lol

 

[N-Kryptic]

Thank you both! Would it necessarily be bad if I kept running DP without tune for a few months? I was planning on getting ktuner a little later, but if it's going to be bad for my car and cause issues running it without a tune I might just get it earlier

I also definitely noticed that I can get decent mpg if I just drive conservative but as soon as I start banging gears and flooring it my mpg goes out the ass lol

Just don't beat on it too much and make sure you are above 2500rpm before you floor it and you should be fine.

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