9 Miles a gallon.
03-28-2011, 07:32 PM
#1
Thread Starter
Join Date: Mar 2011
Location: 2
Posts: 42
9 Miles a gallon.
So my mustang has been in storage for the past winter. I took it out a couple weeks ago and my gas mileage has seemed to drop considerably. I used to get 15 mpg city driving conservatively but after I took it out of storage, I went through half a tank of gas in 55 miles driving conservatively. I just changed the fuel filter and did a oil change and noticed no difference. Any other ideas? Car only has 30,000 miles and is a 4 speed auto.
03-28-2011, 07:48 PM
#3
Thread Starter
Join Date: Mar 2011
Location: 2
Posts: 42
from november to a couple weeks ago. I topped the tank off but before doing that, I burned the old gas out till the low fuel came on (stupid, I know.) I just changed the fuel filter a couple days back too. I even called the gas station to see if they had bad gas and they said that their gas pumps would turn off if they had bad gas.
03-28-2011, 09:36 PM
#7
Thread Starter
Join Date: Mar 2011
Location: 2
Posts: 42
How would that help? Doesn't that just reset it making your gas mileage worse until it "learns" how you drive?
03-28-2011, 09:56 PM
#8
4th Gear Member
Join Date: Nov 2007
Location: NJ / MA
Posts: 1,337
the ecu doesnt learn how "you" drive it learns values based on variables such as temp.
reseting the ECU should always be the first step i diagnosing something, as its extremely easy to do and practically free.
when you said the idle RPMs are at 2000, is that all the time? or after you shift/get car warmed up does it go down?
basically what you need to do, is eliminate any and all variables that you can. try getting gas somewhere else, preferably at a reputable chain. i've gotten bad gas even on a military base, infact thats where i've had the most problems, so i no longer go there and only go to 1 mom/pop shop, or shell/sunoco.
edit: btw, you didnt change anything before or after storage did you? do you notice more of a gas smell from your car? no Service engine soon light?
reseting the ECU should always be the first step i diagnosing something, as its extremely easy to do and practically free.
when you said the idle RPMs are at 2000, is that all the time? or after you shift/get car warmed up does it go down?
basically what you need to do, is eliminate any and all variables that you can. try getting gas somewhere else, preferably at a reputable chain. i've gotten bad gas even on a military base, infact thats where i've had the most problems, so i no longer go there and only go to 1 mom/pop shop, or shell/sunoco.
edit: btw, you didnt change anything before or after storage did you? do you notice more of a gas smell from your car? no Service engine soon light?
Last edited by zero2005; 03-28-2011 at 10:01 PM.
03-29-2011, 02:40 PM
#9
Thread Starter
Join Date: Mar 2011
Location: 2
Posts: 42
the ecu doesnt learn how "you" drive it learns values based on variables such as temp.
reseting the ECU should always be the first step i diagnosing something, as its extremely easy to do and practically free.
when you said the idle RPMs are at 2000, is that all the time? or after you shift/get car warmed up does it go down?
basically what you need to do, is eliminate any and all variables that you can. try getting gas somewhere else, preferably at a reputable chain. i've gotten bad gas even on a military base, infact thats where i've had the most problems, so i no longer go there and only go to 1 mom/pop shop, or shell/sunoco.
edit: btw, you didnt change anything before or after storage did you? do you notice more of a gas smell from your car? no Service engine soon light?
reseting the ECU should always be the first step i diagnosing something, as its extremely easy to do and practically free.
when you said the idle RPMs are at 2000, is that all the time? or after you shift/get car warmed up does it go down?
basically what you need to do, is eliminate any and all variables that you can. try getting gas somewhere else, preferably at a reputable chain. i've gotten bad gas even on a military base, infact thats where i've had the most problems, so i no longer go there and only go to 1 mom/pop shop, or shell/sunoco.
edit: btw, you didnt change anything before or after storage did you? do you notice more of a gas smell from your car? no Service engine soon light?
03-29-2011, 03:25 PM
#10
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Idle speed issues are almost always IAC valve related, with an auto when you put it into gear the transmission loads the engine and when stopped can pull the idle down to a normal range--however during that time stopped the transmission is converting that high idle load, and the gasoline that is creating it, into heat.
Check the IAC and make sure it's doing what it should--unplug it with the engine at normal operating temperature and idling, the engine speed should drop; it may even stall.
If it does not, check the electrical resistance of the IAC coil, there should be 11Ω to 13Ω between the IACs terminal pins. If not the IAC is bad--replace it;
Then check from both pins to the IAC body, there should be more than 10kΩ resistance at each pin. If not the IAC is bad, replace it;
Next with the key on and engine off check the voltage between the red wire at the connector (unplugged) and ground, it should be >= 10.5V. If not there is a wiring problem that needs to be fixed or the PCM is bad...
Check the IAC and make sure it's doing what it should--unplug it with the engine at normal operating temperature and idling, the engine speed should drop; it may even stall.
If it does not, check the electrical resistance of the IAC coil, there should be 11Ω to 13Ω between the IACs terminal pins. If not the IAC is bad--replace it;
Then check from both pins to the IAC body, there should be more than 10kΩ resistance at each pin. If not the IAC is bad, replace it;
Next with the key on and engine off check the voltage between the red wire at the connector (unplugged) and ground, it should be >= 10.5V. If not there is a wiring problem that needs to be fixed or the PCM is bad...