poor mileage
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Joined: Feb 2011
Posts: 69
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From: Point Pleasant Beach NJ
poor mileage
I ve had the 02 since last Nov. Stock with Borla exhaust. I'm averaging only 21 mpg on the highway going straight 65 to 70. I read here that 6 speeds can get +30mpg. Any advice on what to check on , she only got 61K on her.
Racer
Joined: Feb 2004
Posts: 359
Likes: 7
From: St. Paul MN
Does the car idle and seem to cruise ok? You may want to pull any codes from the DIC to see if there are any codes recognized by the computer.
Todd
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
My STOCK 02 ZO6 woud easil get 30 MPG Highway..
Once i started MODDING it,, the mileage started going down. Without a TUNE,, the mods will change the engine total air engine flow and HOSE UP the factory tune.
With out DATA LOGGING the PCM and looking at LTFT ( Long Term Fuel Trims) and several other critical tuning factors,,, your just guessing on why your not getting optium fuel efficiency..
With a proper TUNE,,, my MODDED fuel mileage and POWER SIGNIFICANTLY increassed!
Once i started MODDING it,, the mileage started going down. Without a TUNE,, the mods will change the engine total air engine flow and HOSE UP the factory tune.
With out DATA LOGGING the PCM and looking at LTFT ( Long Term Fuel Trims) and several other critical tuning factors,,, your just guessing on why your not getting optium fuel efficiency..
With a proper TUNE,,, my MODDED fuel mileage and POWER SIGNIFICANTLY increassed!
Melting Slicks
Joined: Mar 2004
Posts: 2,410
Likes: 412
From: Horseshoe Bend ID
something is wrong--terribly wrong, tune, intake, O2 sensors...
Thread Starter
Advanced
Joined: Feb 2011
Posts: 69
Likes: 0
From: Point Pleasant Beach NJ
I run a stock '02 with 6spd also with "just Borlas", and at 65mph I averaged about 33mpg using the DIC average. Measuring from the gas pump shows the DIC is a little optimistic by a couple mpg. Did you check both ways? And reset the average MPG at fill-up?
Does the car idle and seem to cruise ok? You may want to pull any codes from the DIC to see if there are any codes recognized by the computer.
Todd
Does the car idle and seem to cruise ok? You may want to pull any codes from the DIC to see if there are any codes recognized by the computer.
Todd
Racer
Joined: Feb 2004
Posts: 359
Likes: 7
From: St. Paul MN
Did you confirm by the actual fuel bill / gallons, or just using the DIC? Are they close to each other? Perhaps the fuel injectors were upgraded, and the economy is calculated based on stock ones. 65mph, cruise control on, level ground, minimal wind should be 30+mpg.
If the fuel consumption is that far off because the O2s are misreading, your car would probably run poorly or smell pretty bad. Does it perform comparably to other C5's you may have driven?
Does your car roll freely in neutral, and are the tires wearing normally? Have you checked your air filter for restriction?
Perhaps it was de-modded before you bought it, but the tune wasn't returned to stock. If the PCM was locked by the former tuner, you may be up a creek.
Todd
If the fuel consumption is that far off because the O2s are misreading, your car would probably run poorly or smell pretty bad. Does it perform comparably to other C5's you may have driven?
Does your car roll freely in neutral, and are the tires wearing normally? Have you checked your air filter for restriction?
Perhaps it was de-modded before you bought it, but the tune wasn't returned to stock. If the PCM was locked by the former tuner, you may be up a creek.
Todd
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Tech Contributor
Joined: Dec 2006
Posts: 10,962
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From: Van Buren Arkansas
Wounded Warrior Escort '11
I don't remember if the '02's have a pcv valve or not. If it does, check out the connection tube to the intake for holes in it. When were the plugs and plug wires last changed?
Racer
Joined: Feb 2011
Posts: 362
Likes: 0
From: Dallas Texas
Do a tune up, check your o2's. If you want a car good on gas get a Prius or a Honda.
Its a sports car have fun dont stress about the mpg.
I dont get that. You drive a sports car hard and expect to get the same gas mileage as a 2.0L car... HAHAHAHAHA
Its a sports car have fun dont stress about the mpg.
I dont get that. You drive a sports car hard and expect to get the same gas mileage as a 2.0L car... HAHAHAHAHA
Racer
Joined: Feb 2004
Posts: 359
Likes: 7
From: St. Paul MN
The OP also has a "stock" C5 and is rightfully expecting a highway cruise should easily be north of 30mpg, which he's not getting. In-city MPG around 21 I would understand, but not highway cruising. Something is out-of-whack, that's what the OP is trying to deduce.
OP, let us know on the questions posed.
Todd
