Decrease in MPG with AFE CAI

[ronsta]

Recently had an AFE Cold air intake installed on my truck by a shop and immediately noticed that the trip computer showed a full tank would only get about 300 miles to the tank instead of the usual 370-390. I thought I'd give it a month or two and its been 2 but the truck is still swallowing gas. My hand calculations show an average of 14 MPG in mixed city & highway conditions. I've thought about the possibility that it could be the winter fuel mixture but the drop is a bit dramatic.

Any thoughts?

 

[Doozi]

More air = more fuel.

The computer will adjust the amount of fuel to keep the air/fuel ratio where it needs to be. That, along with winter fuel and the colder, more dense air outside, will definitely show a decrease in mileage.

~Doozi

 

[Nuke]

I've had numerous occasions where just the quality of the fuel; mainly the % ethanol; was the cause for a loss of 3-4 MPG. You can see where a combination of things can cause you to drop 70-90 miles per tank.

Is it possible that your foot has developed a liking for the extra sound and performance with the CAI?

 

[brownshoes]

I would have to agree with Nuke, I have the TRD CAI on mine and noticed that a side effect seems to be a correlation between my ear and right foot (my ear likes the notes that my right foot makes when pushed down )

 

[ronsta]

I would have to agree with Nuke, I have the TRD CAI on mine and noticed that a side effect seems to be a correlation between my ear and right foot (my ear likes the notes that my right foot makes when pushed down )

I also agree with that statement however there's no debate about it when you read the trip computer.

Trip Computer Miles to go for a full tank of gas:

Before CAI install: ~385

After the CAI: ~325

These #s are all more or less as I can't recall the exact #

A buddy of mine mentioned that it may have something to do with the mass airflow sensor (MAF)

... still confused... if this goes on any longer and the gas pumps do indeed go to $5 a gallon I might need to put the stock air filter back in just to save some $.

 

[CAFROG]

60 miles difference on the trip computer is 3mpg difference (20 gallon tank....right?). Has your foot become heavier since the CAI install? Like another member posted about his foot and ear relationship.

I can see MPG's going down with more air coming in and the computer delievering more fuel. One suggestion is the thought of re-setting the ECU. I have heard this suggested for such things like exhaust, like the Flowmaster I just put in (although I cannot verify its validity). Another suggestion would be for you to tender foot a whole gas tank. Let it take 10-15 seconds to accelerate up to 25mph and the whole 9 yards. Just take it easy the whole tank and see what results you get (in comparison to what the tank says you'll get) If the MPG loss is a big deal......maybe take it off and put the OEM constict-o-box back on?

 

[ronsta]

*Update, trip computer now says 340 Miles for the full tank.

I did reset the ECU by taking out the 10a etcs & 20a efi fuses for a few minutes before starting the truck again. Still says 340 but maybe it'll adjust after driving a bit? Anyway if I lost 2 MPG and can't get it back then so be it, for now anyway

I'm not saying I'm giving up on this but for the most part I'm a bit more satisfied. Thanks all and if anyone has any more ideas please share.

 

[ALLEGRO]

Shot in the dark here, but make CERTAIN that you do not have a leak allowing air to enter behind the MAF sensor.

Other than that, I agree with ethenol, heavier foot and just cold-weather driving.

Good Luck

 

[ronsta]

CRC MAF cleaner, just went to pep boys and autozone last night, both were at $6.99.

I sprayed and sprayed, full tank still reads lower than my liking, 340 so no change here. I spoke with an employee at auto zone who has a theory, run the tank till its empty empty and then use BP to fill it all the way up, mid grade. Who knows, might work, might not but either way it won't cost me any more than I'd need to anyway.

Oh also put a can of Sea Foam into a full tank as someone suggested. Nothing yet other than idle is at 500 RPMs. Didn't really take note of the idle RPM before the MAF sensor cleaning & the Sea Foam so can't say for sure whether it made a difference or not but I'm sure it didn't hurt.

 

[Milam]

I thought a CAI would increase your MPG. I was about to order one but after reading this I may not.

 

[Milam]

Ok,

I just got off the phone with Scott 951-493-7100 Ext. 7102 at AFE and he said he would take care of you, just give him a call. After speaking with him he said you should gain anywhere from 1-3 MPG with this system. Very nice guy and again he said they would stand behind his product!

 

[SkylineGTRracer]

If your truck is running a stock tune 340-360 in the max you'll get. Out of all the parts I think because I like the sound my MPG went down with my intake but with tuning I gained a little back. Although most if not all has to do with my driving. AFE is great don't get me wrong but seeing how cold it is in your area. That 1-3 MPG increase isn't accurate. It all depends on how you drive, where, when, etc. At most you'll only see maybe half to 1 MPG realistically.

 

[Nuke]

I thought a CAI would increase your MPG. I was about to order one but after reading this I may not.

I get a charge out of folks that think a performance mod will increase gas mileage. And even if it did, the amount increase would be so small that the payback would probably be on the order of years. Even at $4 or $5/gallon, that's a lot of gas you can buy for the cost of the mod.

 

[Milam]

I get a charge out of folks that think a performance mod will increase gas mileage. And even if it did, the amount increase would be so small that the payback would probably be on the order of years. Even at $4 or $5/gallon, that's a lot of gas you can buy for the cost of the mod.

For those of us that don't know will ask questions...I'm glad I could provide you with some entertainment today.

 

[Gecko123]

*Update, trip computer now says 340 Miles for the full tank.

I did reset the ECU by taking out the 10a etcs & 20a efi fuses for a few minutes before starting the truck again. Still says 340 but maybe it'll adjust after driving a bit? Anyway if I lost 2 MPG and can't get it back then so be it, for now anyway

I'm not saying I'm giving up on this but for the most part I'm a bit more satisfied. Thanks all and if anyone has any more ideas please share.

Doesn't the 4runners' automatic transmission learn your driving habits? If you driving it hard, it learns to hold it at a lower gear for longer durations. Does resetting the ECU also reset this? I normally pull the battery to ensure everythihng is reset back to the default factory setting.

 

[Krazynative]

When I installed mine, It seemed to have a little less power and worse MPG's. The MAF sensor isn't calibrated to handle the increased airflow and the fuel mixture is off because of it. I installed the URD MAF sensor calibrator and notice a good increase in power(Ass Dyno) and the MPG's came back up.

It was worth the $200 for the URD.

 

[liqourish]

RESET! FILL UP ALL THE WAY ALL THE TIME... stupid computer will say 380+.....if you dont it will drop gradually to alot.



08 new= mines was near 420.
2010=380 (signature mods)
2011=360 i only fill ~1/4 (5g) for 120lbs less weight

 

[ronsta]

When I installed mine, It seemed to have a little less power and worse MPG's. The MAF sensor isn't calibrated to handle the increased airflow and the fuel mixture is off because of it. I installed the URD MAF sensor calibrator and notice a good increase in power(Ass Dyno) and the MPG's came back up.

It was worth the $200 for the URD.

kRAZY, after reading through a lot of posts and URD's details about the unit I think this might be it!

 

[gaterose]

kRAZY, after reading through a lot of posts and URD's details about the unit I think this might be it!

Make sure you solder in the URD if you buy it!!! I tried connecting mine with vampire taps and lost 3 mpgs, after talking to Gadget I realized that my connections weren't strong enough. I went back and soldered everything in and gained the mileage back.

btw I never lost or gained any (noticeable) mpg from the intake, but the MAF calibrator with the intake helped a little.

 

[FourEyedWilly]

Reading this really sounds like a LOT of time, energy, and money for very little return. So am I reading right that you need to buy a $280 CAI and a $200 UDI thingamajob for 1-2 mpg? What kind of HP gains are you guys realizing? 10-12?