SHO fuel economy decreased

[Seraphim.312]

mods: CAI, CSF Intercooler, straight throttle pipe(noise reducer delete), cat back exhaust

I don't drive the car hard or step on the gas a lot, normally driven 60 - 80 on e-way and 30 - 50 in the city.

I find im constantly resetting the fuel economy on the SHO, keeps staying anywhere between 12mpg and 16mpg average?

Im trying to do the math, do the mods force the computer to adjust for more fuel use?

 

[Joshw0000]

It's tuned for the mods, correct?

Whenever you fill up with gas, do you notice that it takes the car a few seconds to turn over, instead of cranking immediately?

Sent from my Pixel 7 Pro using Tapatalk

 

[Seraphim.312]

It's tuned for the mods, correct?

Whenever you fill up with gas, do you notice that it takes the car a few seconds to turn over, instead of cranking immediately?

Sent from my Pixel 7 Pro using Tapatalk

I haven't had the chance to get a proper tune yet unfortunately‍ but the car turns over as normal, the only time it takes a while is in extreme cold weather.

 

[Joshw0000]

I haven't had the chance to get a proper tune yet unfortunately‍ but the car turns over as normal, the only time it takes a while is in extreme cold weather.

The tune is probably the issue. I suggest starting there and getting it tuned for the mods ASAP.

Sent from my Pixel 7 Pro using Tapatalk

 

[Ta2dResqr]

Agreed. You have made it easier to get colder air in and to get exhaust out. The colder air is denser and requires more fuel on top of the extra air from the lack of resistance. Then it is easier to get the junk out. If you look at your fuel trims, it is probably maxed trying to compensate.

Another problem may be you are going off the numbers on the dash. Try going to the same pump at the same gas station and getting the same fuel (hopefully premium). Top the tank off every time in the same way. Write down your odometer reading and the gallons of fuel. Repeat a few times. Use an app or calculate the actual miles to actual fuel used. Car displays are often off.

 

[kryptto]

Tuning can optimize your efficiency as well. A great tuner will optimize the fuel tables and provide the car with a more responsive experience while saving gas.

 

[SHOrod]

If you've cleaned and re-oiled your reusable filter on your cold air intake, there's a chance that you over-oiled it and the oil has coated your mass air flow sensor. That can cause fuel economy to decrease without any other obvious symptoms. I had this happen on my 1993 SHO, but now I'm trying to remember if my 2011 or 2013 used a MAF sensor since they had a MAP sensor....

-Rod

 

[76FoMoCo]

if the car has higher miles it would benefit from having new #1 O2 sensors.

 

[kryptto]

if the car has higher miles it would benefit from having new #1 O2 sensors.

Learn more every day, tnx

 

[Lostneye]

If you've cleaned and re-oiled your reusable filter on your cold air intake, there's a chance that you over-oiled it and the oil has coated your mass air flow sensor. That can cause fuel economy to decrease without any other obvious symptoms. I had this happen on my 1993 SHO, but now I'm trying to remember if my 2011 or 2013 used a MAF sensor since they had a MAP sensor....

-Rod

O MAF sensor on this gen. Still a good idea to clean the MAP sensors occasionally.

 

[CraxyMitch]

Agreed. You have made it easier to get colder air in and to get exhaust out. The colder air is denser and requires more fuel on top of the extra air from the lack of resistance. Then it is easier to get the junk out. If you look at your fuel trims, it is probably maxed trying to compensate.

Another problem may be you are going off the numbers on the dash. Try going to the same pump at the same gas station and getting the same fuel (hopefully premium). Top the tank off every time in the same way. Write down your odometer reading and the gallons of fuel. Repeat a few times. Use an app or calculate the actual miles to actual fuel used. Car displays are often off.

These calculators in the magic boxes under the plastic... Can they be reset? I'm certain my reads funky, I keep constant logs of every fuel up.

I just got the GH tune package, but subzero temps mean I'm not ready to go switch out my plugs and lose my knuckles...

I'd like to be ahead of this if there's an forscan/ECU fix along the way...