So those of you with intakes... come in here please... v.MPG
 

So I've noticed my cruising MPG (the one in the dash) has been a good bit better after installing the Injen intake (and Perrin pulley too - install at same time) I bought. If I'm in 6th and rolling in the city at 45 or even on the highway at 65ish... It seems like before it'd read 30-34mpg and now it's showing 40+... Which is definitely awesome...

I assume this is because the intake is leaning the car out a bit, which is fine and expected... I just haven't put a full take thru it yet... So I'm wondering if the MPG meter in the dash is fooled, of if you highway commuters with intakes are really noting better cruising MPG?

Thanks

Put my aFe in last Friday. I'll be back here to provide some input when I have it.

Well, there's alot of assumptions here - This is what I've done with our tunes that are in currently development.

1) Reset your AVG MPG meter and then drive like you normally would and let that figure settle. It's done over a period of time, not calculated instantly.

2) If you were correct in your assumptions, then you'd be getting well over 400Miles per full tank of gas. If you are, please let us all know. :)

Cheers,


Bob @ Drift-Office, LLC

I think he is talking about the current mpg display not the average one. I was getting 36 yesterday before the e85 with cruise set at 70mpg. I don't see those figures very often though.

Bob, I reset the ECU (as many say to do) when I put the intake in. I believe this resets the AVG MPG meter (I did reset it tho either way when I did the install just in case)... However I was referring to the REAL TIME MPG meter. Not the average one.


You are correct sir.


I can't wait to get an E85 tune in this thing and open up the exhaust. However to visit family in Philly for Xmas, plane tickets were $650. Looks like the tune/exhaust will wait til sometime in the new year.

Well if its reading like that then check how many miles per fill up it is. It should be a little more then average of what you were getting before.

I understand that, (and if you'd have carefully read the original post you'd have noticed) I was saying I haven't had a full tank yet - so I was curious if others have experienced this before I start to measure.

Leaning out is OK to a point. I would be a bit concerned if you were getting 45mpg. That sounds wayyy too lean to me.

Right, I've rarely seen an intake make it too lean to that extent, I'm kinda wondering if it just throws off the little on board computer that does the realtime mpg.
Will have to start recording results whenever I finish this tank (sometime next week) for a full one.

The current MPG calculation relies on the MAF calibration and fuel trims. You changed the hardware, so the mpg calculation can't be fully trusted.

400 miles out of tank?? That's like 620 km for us Canadians , I only get 400 km per tank .. Heavy right foot I guess


I-Tapatalk

Well I believe I've seen a couple dynos showing an intake leaning out to 14:1 under high RPM/high load. This is entirely too lean. 13.5 is the highest I'd go, IMO.

I agree. 13.5 is about as lean as anyone would want to go all motor.
When I used HPTuners with my Corvette (11.5:1 built motor) we did 12.5:1 to be safe.

Ah. ok, so the MAF is skewed and therefore the data is too.

Thanks sir!

How log do you need to leave the battery disconnected to reset the ecu anyhow?

Woaw 620 km (400miles) that's a dream!!!!
Here in Europe I see around 450 km(280 miles) if cruising on highway and about 320 km (200 miles) when on B road (14 liter/100km).
Did you swap for for a Boxer diesel 2.0 engine :lol:

I was under the impression that the MPG calculation was based off the injector duty and not the airflow.... The injector duty is calculated from the airflow reading and load (amongst a few other things). So it would be calculated AFTER the airflow was already analyzed and not during...

If the airflow reading is skewed in particular conditions, that propagates through a bunch of other calculations. These calculations include fuel trims and engine load used for enrichment scheduling. It also throws off any correction factor used to more closely align the MPG calculation with laboratory tests using fuel flow meters.

Changing anything related to the MAF or the fuel system actually skews a ton of stuff. It's not something to take lightly. The ECU is smart enough that you as a driver usually won't notice it but on a lot of platforms an intake mod is a huge deal. A lot of people remember putting an ebay cold air intake on some 90s Civic without a MAF sensor. So they don't realize how an intake change has so many implications on a modern vehicle.

If the calculations for MPG use MAF as an input then it shouldn't matter. If the maf reads less air, it's going to use less fuel.... the speed/distance don't change.

On a very rudimentary level, say you have two identical cars traveling the same speed with the only difference being MAF reading. Car A with a richer MAF reading is going to get less MPG than Car B with a leaner MAF reading.

My point is, the MPG reading doesn't skew with the MAF, it's a reflection of the MAF skew. It's not like it's going to read 45 MPG when your car is running richer or vice versa. It's just a function of the parameters it sees, which includes the MAF sensor amongst other things. But it directly correlates to the amount of fuel being used.

We all did that. Im waiting for a manufacturer that can provide an intake that retains the same diameter and fins like the stock intake.. I don like those intake that give power by leaning out the mixture...reminds me of those resistors they used to put on the intake air temp sensor to lean the fuel..wrong way to do things imo

You'll be waiting a while for that. The idea is to put more air in the car, volume makes that easiest. A stock tube size cone filter wouldn't add much power if any. Just throw a panel filter in there if you feel that way.

Honestly ANY mods should be done with a tune added for them... however I'm waiting a bit for a re-flash til I have a few other things installed.

How heavy is your foot?? I've hit over 600km's a couple times on mine, with almost all highway driving. I average almost 500km's with mixed city/highway (mostly city) later, with the colder temps and snow tires on.

You might not have to wait THAT long ;)