Help Diagnosing bad MPG
5th Gear Member
Joined: Jul 2008
Posts: 2,057
From: ......
thanks for input guys.
Cone, theres another factor also. We are all supercharged lol so we are gonna have even less mpg, putting the v8 aside.
Will be getting it on the dyno later this week after finals.
Is it a good indicator of running really rich when i pretty much smell gasoline 75% of the time cruising around?
Cone, theres another factor also. We are all supercharged lol so we are gonna have even less mpg, putting the v8 aside.
Will be getting it on the dyno later this week after finals.
Is it a good indicator of running really rich when i pretty much smell gasoline 75% of the time cruising around?
4th Gear Member
Joined: Jan 2005
Posts: 1,190
From: Florida
like bruce said double check and make sure that you don't have a physical fuel leak. otherwise yes, if you smell fuel you're running very rich 
even at full throttle at 11.5:1 I never smell fuel. cruising you should only be burning a very small amount of fuel and should never smell fuel when tuned correctly.
even at full throttle at 11.5:1 I never smell fuel. cruising you should only be burning a very small amount of fuel and should never smell fuel when tuned correctly.
6th Gear Member
Joined: Sep 2006
Posts: 11,278
From: Gainesville, FL
When my accel coils started to go out, I was getting bad gas mileage and got a lean code.
From your post, I would blame the tune. Not sure how well the 02 sensors work without cats, but the readings from the 02 sensors is what the ecm uses to calculate how much fuel to add or subtract at idle and part throttle. My bad mileage was because the coils weren't firing right and the ecm thought it was running lean, when in reality it wasn't burning the oxygen that was there.
From your post, I would blame the tune. Not sure how well the 02 sensors work without cats, but the readings from the 02 sensors is what the ecm uses to calculate how much fuel to add or subtract at idle and part throttle. My bad mileage was because the coils weren't firing right and the ecm thought it was running lean, when in reality it wasn't burning the oxygen that was there.
Last edited by moosestang; May 9, 2010 at 08:30 AM.
5th Gear Member
Joined: Aug 2007
Posts: 2,041
From: Hollister, CA
Its the tune isn't right at all. You may smell a little gas if you have not cats but it really shouldn't be all that bad. For piece of mind I'd check the fuel connection on the driver side to make sure you don't have any leaks. Should right under the intake tube. There was a guy here that had a bad connection and caused his car to catch fire.
Last edited by loots06; May 9, 2010 at 04:53 PM.
4th Gear Member
Joined: Dec 2007
Posts: 1,491
From: TEXAS
Brenspeed Stage II so around 420-430rwhp on Brenspeed tune
Thread Starter
4th Gear Member
Joined: Jul 2007
Posts: 1,474
From: Houston TX
Will be checking all connections today.
02 sensors were not turned off for some reason by jdm.
Having no cats help contribute to the gas smell, but prior supercharger install, it wasnt as pronounced as it is now. I even smell it on the hwy with my windows down
02 sensors were not turned off for some reason by jdm.
Having no cats help contribute to the gas smell, but prior supercharger install, it wasnt as pronounced as it is now. I even smell it on the hwy with my windows down
6th Gear Member
Joined: Sep 2006
Posts: 11,278
From: Gainesville, FL
Sounds like you have a gas leak. Better check all injectors and fuel line connections.
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