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Old 11-06-2003, 03:12 AM   #1
Yebisu69
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Default Cobb CAI killed my gas mileage

Am I missing something here?

I was getting 20-23 mpg with the ganzflow. Once I swapped it out for the COBB, my gas mileage has been in the 16-19 mpg range.

Anyone have a similar experience? Anyone have an explanation?
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Old 11-06-2003, 05:54 AM   #2
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Interesting.... my MPG dropped after I put in my K&N from 28-29 to 26? I just attributed it to my heavier foot! (MY00 RS)

But from 20-23 to 16-19?? Did you reset the ecu? If that dosent change it after a couple tanks then swap back to the ganz to see if it goes back up...then you know the culprit..??

btw was the cobb new or used? did you clean it? oil it? what MY?
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Old 11-06-2003, 05:54 AM   #3
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probably because you are flooring it more often...
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Old 11-06-2003, 09:56 AM   #4
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What grade gas are you using? Stock the RS is tuned to run 87, you aren't going to see benefits of running higher unless you are pinging. w/ headers and a ganz flo, I get about 27.5 mpg
AO
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Old 11-06-2003, 10:46 AM   #5
Matt Monson
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Quote:
Originally posted by m750
What grade gas are you using? Stock the RS is tuned to run 87, you aren't going to see benefits of running higher unless you are pinging. w/ headers and a ganz flo, I get about 27.5 mpg
AO
Yeah what he said. Both your mileage numbers seem really low to me. I got better gas mileage with my Cobb CAI (when not leadfooted) by about 2-3mpg over just a K&N drop in filter. I always use 87 or 88 octane and get an average of 26mpg on mixed around town and hwy. When I go on the open road and keep it 80 or under, my hwy tanks are more like 29-31mpg...

CURRENT MODS:
Cobb CAI
Stromung TT cat back
Copper Plugs
UD pulley
Also, I live a 5200ft. My gas mileage went up about 2mpg when I moved from sea level to a mile high.
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Old 11-06-2003, 02:45 PM   #6
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That seems really low. I got 30+ on a cross country road trip averaging about 80 MPH the whole way. I usually get about 21-24 on a normal tank, but it is all city driving.
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Old 11-06-2003, 03:08 PM   #7
Yebisu69
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I bought the COBB used and cleaned it before installing it. I bought the K&N cleaning kit from cobb. The Intake is for 2002+.

I keep 89 octane gas in the car. The car has been through 2 tanks and I an getting about 20% reduction in gas mileage.

I have been keep my foot light just to see.

Running my car in stop and go traffic in NYC kills a lot of gas. On the highway, if I am just crusing, I can get gas mileage of about 25 mpg, but that is because its a 4EAT.

I think I need a ECU reset.

Current Mods are:
Stromung Catback
COBB CAI
SPT struts and springs
FHI 20mm rear sway
Subie 4-pot front brakes
99 RS Wheels
Continental contiextremecontacts (stock size)
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Old 11-06-2003, 11:59 PM   #8
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I would say reset your ECU. I know my city mileage sucks really bad after an ECU reset. It usually takes 3 tanks to get back to normalish for me. My gas mileage also increased a hair after intake and exhaust.

edit for spelling.

Last edited by silent_rob_95; 11-07-2003 at 12:33 AM.
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Old 11-07-2003, 12:18 AM   #9
j.reed
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My MPG with my Cobb stayed the same... even with my heavier foot.
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Old 11-07-2003, 12:35 AM   #10
SubyBean
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sorry bro hate to tell you this but MPG with a Modded AUTO RS sucks take it from me. i generally get 19 mpg if im lucky on a road trip around the city its more like 17 or so and that is with an SAFC but it might be due to that fact of my suspension mods and the added weight

My mods
Injen CAI
Borla Headers
GFB Pullies
Custom Catback
P1 Springs
V5 struts
F and R strut bars
Rear Sway bar
Harness bar
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Old 11-07-2003, 01:08 AM   #11
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Its because of NYC. I got 20mph in my EJ18 the other week cause it was all traffic stop and go all the time for that whole tank...
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Old 11-07-2003, 01:56 AM   #12
Yebisu69
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Just went throught the second tank of gas since installing the cobb CAI. Got 18 mpg on the nose.

This is the third tank.

My gas milage with the ganzflow CAI and the stromung catback was pretty decent. I didn't think that the change between ganzflow and Cobb would be this dramatic. I hope the ECU adjusts fully after this tank.

Also, I wonder if the gas stations have switched to winter gas yet. I usually lose a few mpg due to the switch.
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Old 11-07-2003, 04:24 AM   #13
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From what I have read sounds about right to me. I typically only get about 250 miles out of a tank of gas which only equals about 16 mpg ...If I'd lay off the gas I'm sure it get better. My highway mileage is about 350 to 400 miles out of a tank of gas so that equals about 21-23 mpg, another ......I know my problem is I need to lay off the gas. It's just so much fun to hear my intake and exhaust!

Oh, my mods are Cobb CAI, Borla Headers, and borla cat-back on a 4EAT so don't feel bad. I've actually switched to using 89 octane in mine because I was hearing pinging and sometimes still do too.
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Old 11-07-2003, 08:19 AM   #14
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Quote:
Originally posted by CheezeWeezle
From what I have read sounds about right to me. I typically only get about 250 miles out of a tank of gas which only equals about 16 mpg ...If I'd lay off the gas I'm sure it get better. My highway mileage is about 350 to 400 miles out of a tank of gas so that equals about 21-23 mpg,
um, 350 on 14 g = 25 mpg
350 on 13g = 26 mpg
That's what I'd consider normal. Now 250 out of a tank, is low, but I'm assuming thats stop and go, I typically don't drive in that much, so I've got 0 comparison.
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Old 11-07-2003, 09:12 AM   #15
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Quote:
Originally posted by m750
um, 350 on 14 g = 25 mpg
350 on 13g = 26 mpg
That's what I'd consider normal. Now 250 out of a tank, is low, but I'm assuming thats stop and go, I typically don't drive in that much, so I've got 0 comparison.
I'm counting the full 16 gallon tank....... ...then redo the math...
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Old 11-07-2003, 12:15 PM   #16
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Quote:
Originally posted by CheezeWeezle
I'm counting the full 16 gallon tank....... ...then redo the math...
did you push it into the gas station?

and it's 15.9 gal.
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Old 11-07-2003, 12:20 PM   #17
Matt Monson
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Quote:
Originally posted by DanzBorin
did you push it into the gas station?

and it's 15.9 gal.
I have run out with 1.5 gallons left in the tank. Pick up on these cars sucks...
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Old 11-07-2003, 12:30 PM   #18
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Quote:
Originally posted by Matt Monson
I have run out with 1.5 gallons left in the tank. Pick up on these cars sucks...
that's my point... not much chance actually using all of the gas...
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Old 11-07-2003, 02:14 PM   #19
silent_rob_95
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Quote:
Originally posted by CheezeWeezle
From what I have read sounds about right to me. I typically only get about 250 miles out of a tank of gas which only equals about 16 mpg ...If I'd lay off the gas I'm sure it get better. My highway mileage is about 350 to 400 miles out of a tank of gas so that equals about 21-23 mpg, another ......I know my problem is I need to lay off the gas. It's just so much fun to hear my intake and exhaust!

Oh, my mods are Cobb CAI, Borla Headers, and borla cat-back on a 4EAT so don't feel bad. I've actually switched to using 89 octane in mine because I was hearing pinging and sometimes still do too.
That is what I get about. I do push my car too hard as well. My mods are Cobb CAI, stromung midpipe, STI v7 muffler, perrin pully, and some other odds and ends for power. I usually can squeeze out 260 miles city. The Auto RS's do get :/ mileage in the city.

Also check your O2 Sensor just in case. Maybe you are running really rich and are buring more fuel then needed. I'm not sure if this can do something but I would just check if it was me.
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Old 11-07-2003, 03:47 PM   #20
CheezeWeezle
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Wouldn't I have blown a cel if the O2 sesor was functioning improperly?.....I do get a lot and I do mean a lot of backfires. I can controll them though. They sound like they are coming from the header/cat area too..... .....At any rate my wife calls my car teh gas guzzler right now, and to some extent she is right .....Oh, I've only had the exhaust parts on for about 5-6k and only have 30k on the odo.....Would the sensor go bad already?

Mr. Borin, thanks for the technicallity ...I was rounding up and yes I almost have had the car sputtering up to the gas station ....I don't do that anymore.....
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Old 11-07-2003, 04:28 PM   #21
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I ran out of gas, and only filled up w/ 14.5 gallons. Assuming you don't run out of gas everytime, you need to re-estimate. Sorry to be anal, but when talking about the difference of 2 gallons is a big difference in mpg.
AO
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Old 11-07-2003, 05:10 PM   #22
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Quote:
Originally posted by CheezeWeezle
I do get a lot and I do mean a lot of backfires. I can controll them though. They sound like they are coming from the header/cat area too.....
I get this too, with a cobb and stromung cat back. My MPG suck as well, about 20 mpg. I'm a little heavy footed, but c'mon. people here are claiming 30 mpg at points? I WISH I could get near that.

Don't know what the problem is.
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Old 11-07-2003, 05:28 PM   #23
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On my last trip up to santa barbara, i got 29mpg both ways, i have a 5spd and minor mods
Cobb intake
ground wireing kit
flowmaster muff
t-body bypass mod

your mileage will greatly vary with how fast you are going. try to keep the RPMs around 3100 or so. I realy want to put some larger tires on so i can cruse at 80 and have the car stay at 3100rpms. I am not a street racer so i dont car about off the line power.
Shane
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Old 11-07-2003, 10:21 PM   #24
CheezeWeezle
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Ok, I just filled up and had to put in 12 gallons in. I had 250 miles on the trip reader so that would mean I got 20.8 mpg? .....that's according to the handy dandy pda I have.. ...So with the recalculation of my highway miles with about 350 miles out of 12 or so gallons mean I am getting round about 29.16 mpg? ...If that's the case then it's better than I thought; just seems as though with a bigger tank than my old car, a neon, I would be getting a little further, oh well
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Old 11-10-2003, 12:58 AM   #25
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The way I designed the ganzflow is to produce more fuel from thin air magically. I also sell the Cobb just in case you don't need that

Larry Ganz
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