Intercooler and mpg

[EkSean]

So I was averaging 41-43mpg on a drive I take quite often. I installed a new intercooler today and it’s awesome. The only thing I noticed was my mpg on this same drive went down majorly. 34-36mpg. Nothing has changed except the intercooler. Anyone else experiencing this or have an answer to what’s going on there?

EDIT: I should have mentioned this but it’s a deporacing fmic. I’m also on ktuner with tsp1 and I always drive in map 3 in normal mode. PRL SRI street maf and PRL catted DP/FP.

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[FlexRex]

How are you calculating before vs now? Also, were you on the same tune and gas? Your driving style is same? When was one vs other, ambient temps?

 

[si_well]

This is just me spit balling here.

Swapping out the OEM FMIC to a larger aftermarket one, depending on which brand you went with, will likely have vary from the OEM in the pressure of air going into hot side and thus causing a difference in the density and pressure of cool air coming out the other side. That's obviously the point of them. Your ECU is programmed to account for this by sensing the amount of air coming in and delivering more fuel as a response to keep the air to fuel ratio in balance. It's possible it could overcompensate by delivering more fuel than really needed causing you to run rich and it might take some time for your ECU to adapt to these changes if they fall well beyond the standard deviation from what it has sensed prior to the new intercooler. I would also suspect that an aftermarket tune would be able to account for this better/quicker than the factory tune would, so if you're running a factory tune this seems more plausible.

I would take a look at other variables like FlexRex mentioned first though. It is likely that something else could have resulted in this difference that is being overlooked because the intercooler is so fresh in your head.

Again, this is just spit balling. I'm not a mechanic by any means but I do have a mechanical understanding of how everything works so please correct me if I am far off base with this.

 

[EkSean]

How are you calculating before vs now? Also, were you on the same tune and gas? Your driving style is same? When was one vs other, ambient temps?

Just from the trip meter. Same gas, same tune, same driving habit and same speed with cruise. The temps usually range from 65-70. I’ve driven this road a lot since I’ve had the car in many different conditions and usually averages 40-43mpg. Took the drive right after installing the intercooler and it was 36mpg on the way there then 34mpg back. It could be nothing at all and I’m just stupid but I wanna see if I can understand why.

 

[EkSean]

This is just me spit balling here.

Swapping out the OEM FMIC to a larger aftermarket one, depending on which brand you went with, will likely have vary from the OEM in the pressure of air going into hot side and thus causing a difference in the density and pressure of cool air coming out the other side. That's obviously the point of them. Your ECU is programmed to account for this by sensing the amount of air coming in and delivering more fuel as a response to keep the air to fuel ratio in balance. It's possible it could overcompensate by delivering more fuel than really needed causing you to run rich and it might take some time for your ECU to adapt to these changes if they fall well beyond the standard deviation from what it has sensed prior to the new intercooler. I would also suspect that an aftermarket tune would be able to account for this better/quicker than the factory tune would, so if you're running a factory tune this seems more plausible.

I would take a look at other variables like FlexRex mentioned first though. It is likely that something else could have resulted in this difference that is being overlooked because the intercooler is so fresh in your head.

Again, this is just spit balling. I'm not a mechanic by any means but I do have a mechanical understanding of how everything works so please correct me if I am far off base with this.

I was also thinking maybe the larger volume of air the ecu is seeing has something to do with it. I hope it gets better but if the mpg stay lower then so be it, I do like the fact it losses some psi but power is the same if not more. Less stress on the motor despite lowered fuel economy. Thanks for the insight though, I could definitely see that.

 

[abracadaniel_]

same thing happened to me once i went from stock to dp/fp, cai, fmic and ktuner tsp stage 1, changed my driving a little bit because i was on the gas more to feel all the new power, but once i changed to map 1 for daily driving, i went back up. im sure that'll help you as well. also once i changed out my summer tires to all season china tires, my mpgs improved by about 3+ as well.

 

[Jeffers]

Did you disconnect the battery when you did the install?
I've heard that ECU's sometimes have to relearn after that.
And that it takes a few drive cycles to straighten itself out.

 

[EkSean]

Did you disconnect the battery when you did the install?
I've heard that ECU's sometimes have to relearn after that.
And that it takes a few drive cycles to straighten itself out.

I did not disconnect the battery. You think I should and see what happens over the next few drive cycles?

 

[TypeSiR]

I did not disconnect the battery. You think I should and see what happens over the next few drive cycles?

No, just continue to drive normally to allow the ECU to relearn everything. What’s the make (Depo?) of IC and and how was fitment (possible leak)? Also, temps in SoCal have been unseasonably cold (40s-60s) and affect MPG.

 

[EkSean]

No, just continue to drive normally to allow the ECU to relearn everything. What’s the make (Depo?) of IC and and how was fitment (possible leak)? Also, temps in SoCal have been unseasonably cold (40s-60s) and affect MPG.

Yea it’s depo. The fitment wasn't bad and I quadruple checked the hoses and everything before put the bumper back on. I thought it might be a boost leak too. I did some pulls and the boost was pretty consistent same with af but I’m gonna recheck everything again.

 

[EkSean]

what makes it so awesome?....the loss in MPG?

why do you consider it to be "awesome" ??

for a product to be "awesome" it should be doing something better then a stock OEM product can do, and I am not seeing that here,

you are wasting your time and money

That is your opinion. Awesome to you might be something different to someone else. The iat’s are more consistent, I prefer the boost to be lower and making the same power and come in a little later so it’s a little “easier” on components. The car feels better than it did before. I’ll trade mpg for fun, in my book anyway. I’m just trying to figure out what it could be. So no, I didn’t waste any of my money.

 

[FlexRex]

Do you have logs pre and post w ambient, iat, iat2?

 

[EkSean]

Do you have logs pre and post w ambient, iat, iat2?

I don’t unfortunately, I should have done it to see the difference and I’m sure it would answer my question. I might just deal with it and see how it goes as I drive it more.

 

[amirza786]

what makes it so awesome?....the loss in MPG?

why do you consider it to be "awesome" ??

for a product to be "awesome" it should be doing something better then a stock OEM product can do, and I am not seeing that here,

you are wasting your time and money

Ha ha Mr. Sunshine. It must be really, really cold on your side of the US. Hopefully you will have a much happier and warmer New Years and 2020 my friend

 

[gtman]

Mark, lay off the dude. There's nothing wrong with adding a better intercooler and if he likes it, that's all that matters.

OP, as far as the MPG loss, it's possible you may be on the throttle a bit more. I think we all tend to do this when we add a new performance mod. Drive with it a bit more and report back. Post a datalog here if you get a chance. Good luck.

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