Bad MPG

[Not Jo3L]

I don't know why I am getting such bad gas mileage. I recently filled up 3/4 my tank and in less then a week i have only gone 40 miles(all city) and the notch went from the 1st notch to the middle. That means I am probably only going to get another 40 miles till i reach 1/4 tank left then maybe 30-35 till empty.

Currently my mods are injen intake(cheapo filter), RB exhaust, and custom catless midpipe. I have a bad pre-cat that keeps the CEL on and I think that maybe it is blocking the exhaust piping. Or could it be my filter is bad? Or maybe tire pressure?

Anybody with any ideas please comment. Trying to get the most of my moneys worth at the pump.

 

[lowandslow]

I think you answered that question yourself. Any time you have a CEL on the car is not running properly. Until you address that problem I can't see you getting any better mileage. Obviously tire pressures and such can be checked quick to take them off the list.

Matt

 

[hi-perf]

check your filter

if its a cheap piece of s*** like you said, replace it with a k&n cone or get a new one from injen.

after driving for nearly two years in dirty ass texas without cleaning mine, it was caked on disgusting and after cleaning it (twice, yes it was that dirty), I noticed that the missing power and gas mileage came back.

 

[Not Jo3L]

Allright thanks for your guys input. Ive had the CEL ever since ive had my car and saw reasonable gas mileage. The only instance I can compared it to off the top of my head was 90 miles(highway) and I only used 1/4 the tank. I know this is highway so it is different, but should not be that different from my city mpg. I found this link for a AEM dryflow on ebay. It was like their outlet store and they sell everything hella cheap.

https://www.ebay.com (commissions earned)

I am probably going to purchase this soon.

 

[Not Jo3L]

Tire pressure is
LF-31 RF-33

LB-29 RB-27

 

[lowandslow]

Tire pressures shuld be adjusted, but they are not low by any means. So don't look at that for hte mileage loss. I run 32 front 34 rear on my car with 17's.

A decent filter would be a good start. When was the last time you changed spark plugs?

Matt

 

[Not Jo3L]

Spark plugs were replaced before summer with brand new NGK cant remember the exact numbers and the wires...right with a brand new 1.8 coilpack at the dealership.

I went from a K&N panel filter to my injen intake with cheapo filter.

 

[Not Jo3L]

Pumped up my tires to 33 each but still getting bad MPG. Went only 170 city miles with a little highway on one tank. WTF!

 

[Jake_isr]

A CEL will make the car run in a "safe mode" sometimes using a lot more fuel.

 

[NCZ13]

Pumped up my tires to 33 each but still getting bad MPG. Went only 170 city miles with a little highway on one tank. WTF!

=O

i usually get about 240 city... which still feels low for me...

 

[Not Jo3L]

Just filled up my tank today and only got 198 miles in that one tank. This is with my new AEM filter on my CAI too.

edit...jake do you think if i use a spark plug non fouler with the O2 sensor currently in my pre-cat..would it recognize it as working again?

 

[Jake_isr]

it should. You might have to take your neg battery cable off afterwards so to recycle the computer.

 

[Not Jo3L]

Before when I would unplug the battery it would show no CEL until about 100 miles and then it would turn on and flash at me.

 

[Jake_isr]

do the non fowler first then the battery.

 

[iluvmacs]

When I drove all city miles, I drove pretty aggressively. 22 MPG was common. Now that I drive highway, if I drive consistently over 70 MPH average, I get between 28 and 31 MPG. It's hilly here, but if I drive under 70 MPG average, I get 32-35 MPG.

Many things factor into mileage. If you're engine is tuned up, and your tires are fine look for other sources of resistance first.

Do your tires spin freely when off the ground? Brakes can be sticky and warped rotors kill mileage. Let the car idle in gear when in the air. Make sure both front tires go the same speed, or you have a sticky tire. Same goes for bearings and CV joints. I have a CV joint that knocks when the suspension is fully extended (like when the car is in the air). It's perfectly fine at normal ride height though.

Check your aerodynamics. If you have big dents, or a big wing on the back you'll notice a MPG problem.

Finally, check your right foot. Fast acceleration, frequent braking, and high speeds all kill mileage. I spend a lot of time on the highway 20-40 yards behind semi trucks to catch a draft. It makes a huge difference.

 

[Not Jo3L]

Yeah the mpg actually went up..i guess the ecu finally adjusted after the CAI and Exhaust..one tank got me like 220-250 miles in the city. Now after installing headers I have to wait once again for the Ecu to fully adjust. Currently I have the two O2 sensor codes (P1135 and P1141) so I am sure this is part of the problem.

 

[Kymerik]

Dear god, I'm on my 3rd tank and the first two I've gotten 335miles (12.8gallons - 26.1mpg - I was a bit rough on it just seeing what the motor had) second i got 340 on 11.9gallons - 28.6MPG - about 70% hwy 30% city and I thought that was bad for a 4 banger.

 

[sanblaster]

i'm getting about 200 miles on my tank with the 2nd gen. i am filling every week. brutal.