So here's the deal. I filled my tank up to half yesterday, reset my trip odometer, and today, it's sitting at a quarter tank, and my odometer reads around 50km. That's 31 miles for you 'murricans.

The only things that are under my hood are a grounding kit, custom short ram intake (see vehicle profile), and a RalliArt oil cap. Everything else is stock.

What could be causing this really crappy mileage?

Does the SRI have anything to do with it? I've been meaning to build a heatshield, but haven't gotten around to it, does sucking in lukewarm air affect it? I say lukewarm because weather around here is constantly at -30's, so the air going into the SRI can't be that hot.

The RalliArt oil cap is not an authentic one, and fitment is a little loose. It seals the oil tank properly, but it's not tight. Does the pressure in the oil tank affect anything?

I'm stumped, could use some help from the experts. Thanks in advance.

 

Try switching back to the stock cap. That is a good starting point. Thats all I can think of.

 

I'd agree. I would think you'd have to be driving through the fires of hell for the air temp to lower MPG that much.

 

great, i'll try that. anyone else agree?

any technical reason behind it? i'm not a hardcore tuner, so i'd like to know the reason oil pressure affects my mileage so much.

 

why would an oil cap lower your mpg? its just a cover..unless there is some change in pressure that the cap does that i don't know about..i think its the SRI...intakes use up alot of gas. grounding kits actually help you save gas by reducing the resistance in the spark, so you get a bigger spark = better fuel burn.

after my cold air from AEM..my mpg went from 320miles/tank to now..a shiety 240 - 270 mile/tank.

if you want performance, you gotta bite the bullet on fuel economy.

 

i knew i'd take a hit on fuel economy with the SRI, just didn't think it was that much, i just want to know if there's anything else affecting it.

i'll try putting the oil cap back to stock, if that doesn't help, then i'll eat the cost.

:P

 

maybe resetting the ecu?

 

no, i unplugged the battery when i installed the SRI, the MAS should have learned the new airflow, i don' t think that's the problem. unless you mean resetting the ECU for some other purpose.

 

My mileage drop slightly when I installed my SRI. Most of that was I was hard on the gas just so I could hear the new sound. After I got used to it my mileage was just about the same.

 

Same for me. The first tank of gas after I installed the CAI had 5 more MPG.

 

ok heres what happened to me. stock: gas mileage was decent, nothing special (i guess you could say kinda bad). after installing SRI: very bad! (shocked as how the motor would just eat up the gas). after installing header: gas mileage is better than ever!?!?!? (even better than stock). ok i know it sounds crazy. many of my buddy's have told me so. but i swear thats the turnout. i dont know why, but its as if the header balanced out the airflow from the intake. i remember when i would floor it on the express way with the intake. the gas would just eat up. now with the intake and header, the needle HARDLY moves when i get on the gas. its weird. well thats my experience. well see how it goes after the catback.

 

This probably won't prove anything, but filling your tank to half and guaging how many miles to get to 1/4 is not accurate at all. When my guage gets to 1/2 I know I only have about 1/3 tank left. The only accurate way to test mpg is to start with a full tank, then drive for at least 100 miles and fill the tank to full again. Divide the miles driven by the gallons you had to refill. But if that still shows you as having poor gas mileage, I dunno. My mpg got a little better after SRI, and went back to original after reflash.

 

yup, like these other guys said... my SRI improved my milage. I have a SRI, ground kit, the same ralliart oilcap as you, headers, downpipe, test pipe, and a magnaflow exhaust.... Im getting better milage as I was stock. Crazy thing is, even when it has been as cold as 20*-30* outside, I've still been getting 27-29mpg.

 

he said his post-SRI mileage dropped.
It makes some sense, I think. This is just a GUESS:

The MAS is reading more air in, but there isn't a place for it to go (stock header is very restrictive). So to compensate for more air, it dumps more fuel (to keep the mix even). Again, no place for the exhaust to go, so more of it stays in the cylinder than if the headers were extracting the exhaust. This 'old' exhaust gets mixed with some fresh air and lots of fuel. Rinse, repeat as necessary.
I guess what I'm trying to reason out is that the blockage of the stock headers is making the motor less efficient with the more open SRI. We all know engines are about balance. If he'd gone headers first and opened things up I think there would have been a performance and slight mpg increase. The the SRI would have more of an effect and it would be more positive in terms of better mileage.

Well, maybe not- I started mashing my throttle after both installs and stayed around 25MPG

 

My theory: every mod you add to your Lancer also adds a little lead to your ego, and therefore your foot! That's probably why I saw a slight drop in mpg right after I got the reflash.