My Father and I were sitting down and discussing my purchase of a decently neglected Convertible Fox last night. There weren't too many problems (it wasn't a total basket case-- or I hope that it isn't), but there is something bothering me. I'm only getting 13 mpg. This bothers me mainly because I bought the car hoping I would get 15 or more and still have the thrills of having a small block V8. Here's how I figure it. I drive 34 Miles per day. I fill up every four days and I have found that I am using 10 gallons in four days (I like to fill up when the gauge reads 1/4-- I have 5 gallons left over every time as buffer space). Now, 34 x 4 = 136 and 136/10= 13.6 miles per gallon. This is a bone stock car with the exception of a full catback exhaust added by the PO, and by no means do I hot rod around in this car, so I know it isn't because I'm getting crazy and flogging it everywhere. Every now and then I smell gas pretty strongly on the car. Not every day but once in a while. I've never dealt with a fuel injected car before (my last car was Carbed and all of the other cars I've every worked on are carbed). What should I check/replace to improve mileage? (The more I save on gas, the more I can put towards getting the seats reupholstered, they're pretty bad.) Other things to note: The temp stays pegged at the bar right above 130 on the gauge when I'm driving down the road, and I know I need a new heater core and maybe a new radiator. I'm having the latter checked out. Any help you guys could give would be great.
Gas Mileage
- Thread starter Alan David Hudson
- Start date
ID89GT
10 Year Member
Assuming that your car has 2.73's (I think that most verts did) like mine did your mileage will suffer in town, once you get on the highway and up to about 60mph the mpg will get better. Do a tune up (copper core plugs, air filter, plug wires, distributor cap, new thermostat and oil change) and check for vacuum leaks. If possible make sure there are not any codes that would affect the mileage, might have a bad O2 or something.
I had a gas smell in my fox too, changed the tank and grommet and fixed it.
I had a gas smell in my fox too, changed the tank and grommet and fixed it.
Flavadave4
Active Member
A tune up is a must, the parts are fairly inexpensive and very easy to replace. A new thermostat would be a good idea too if you suspect the car is not getting up to normal operating temp. I had a simular situation with an 87 LX 'vert 2 years ago, turns out the catalytic converters were plugged and really holding back the exhaust from flowing. I ended up using a catless H-pipe I had laying around and that really helped with MPG and overall performance of the engine. My 89 GT even with 3.73 gears will pull off 24mpg on the highway which to me is great.
If you have a GPS I would use it to confirm your spedometer is correct or close and then start calculating your MPG based on it. Is the car a automatic or manual transmission? Also jack the car up and figure out what gears you have in the rear end.
Report back to us, and welcome to Stangnet
If you have a GPS I would use it to confirm your spedometer is correct or close and then start calculating your MPG based on it. Is the car a automatic or manual transmission? Also jack the car up and figure out what gears you have in the rear end.
Report back to us, and welcome to Stangnet
Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.
Dumping the computer diagnostic codes on 86-95 Mustangs
Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.
Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.
Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.
Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.
Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.
If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.
The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.
89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.
The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.
WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.
What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems
Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.
Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.
Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.
Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.
Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Dumping the computer diagnostic codes on 86-95 Mustangs
Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.
Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.
Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.
Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.
Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.
If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.
The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.
89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.
The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.
WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.
What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems
Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.
Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.
Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.
Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.
Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Attachments
I'll try the code dump tomorrow. Lord knows what kind of codes it could have. I know it isn't the cats, plugs, plugwires, EGR, O2, Dizzy cap, or any of the other emissions garbage as the PO replaced all of that three days before I bought the car and he handed me the receipts for it all. All of that is new. I do need to install the new thermostat though and fix the danged rear main seal (I have a strong feeling that the mild oil leak may have something to do with this, it isn't terribly bad though). I'll definitely check the code dump though. Which do you recommend, dumping it while the car is running or no? I've never had to deal with a computer before, but I'm very eager to learn how to.
Even little things like proper tire pressures and front end alignment can have a big impact on fuel economy.
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