really bad gas mileage???

green94droptop · 05-16-2001, 11:07 PM

Yo guys...

I purchased a 94 gt conv with a 5 speed about 1 month ago. It has 50k miles on it and it runs perfectly.

But what I didn't expect was this kind of gas mileage...12-13 miles to the gal. I went ahead and changed plugs (cold), wires (9mm FMS), cap/rotor (Accel), did a 180* thermo, and advanced the timing to 14*. I thought I should get upto about 17-18 mi/gal. Filled 'er up the other day with 93 like always,(about 14 gallons) and now I'm at a half tank and have only driven about 90 miles.

Now, I am babying the car right now; just regular city driving.

When I checked out the old plugs (they looked like the original's), they were unbeleiveably gaped to .080. I went ahead and gaped the new accel cold plugs at .052 like Ford calls for. It runs a whole heck of a lot smoother. But the gas mileage is horrible.

Any suggestions???

Thanks, guys!

------------------
Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 2 chamber flow's, 14* timing, and still workin' on the rest!

[This message has been edited by green94droptop (edited 05-17-2001).]

slo95 · 05-17-2001, 11:20 AM

think the previous owner put gears in it? sounds about like what i get in my 95 vert with 3.73's. about 15 city / 19 highway, but I like the gas pedal...

jimberg · 05-17-2001, 12:12 PM

The fuel gauge is not linear so I wouldn't base your calculations on that. You may also want to verify that your speedometer, and, therefore, your odometer are accurate.

90 does seem low, though, for half a tank. I'm at like 110 or so with my engine and 3.55 gears.

Gears would not make that much a difference.

------------------
351W 89 Mustang GT Convertible

lx mike · 05-17-2001, 12:34 PM

wait till you need gas to see how far you go then you can see what your mileage is, some cars the needle moves faster from full to half than it does from half to empty, run it down as far as u feel comfortable with then fill it back up and figure your mileage from there.

------------------
93-LX: 5 Speed, Flow's with H-Pipe, 3.73's Sub's and K&N.

Jerm95gt · 05-17-2001, 03:33 PM

i drive around hmmm lets say 20 miles a day?5 days a week and i fill up at least once a week....you notice a real difference if u rev it high or not....i came up with the plan i try to follow which is reving low and not driving to fast mon-thurs and on friday+weekend i race some and rev it incredibly high....if i rev high during the weekend i can kill about 3/4 tank.You should be able to get like 15mpg max city driving...the highest you can get is 17 what ford says and i know thats a joke.ps: doesn't the car ask for 87? buy 87 and save some cash

dinomite · 05-17-2001, 05:02 PM

Its a new car, i'd bet that your driving it kinda hard, and that would explain your mileage. I get about 17mpg all city, but if i am really reved up (sorry pun) after i fill it up, and heavy on hte gas, that can drop to 12 easy.

green94droptop · 05-17-2001, 05:03 PM

Thanks guys...

This is the first tank I have put in since the tune up.

I don't think the previous owner had put gears in it. They seem like their 3.08's.

And as far as the gas gauge being acurate, there is no way to really tell, or is there?

Jerm95gt: I advanced my timing when I did the tune up. I put it at 14deg and I know if I put anything less than 93 in it pings. And it pings on really really hot days here in FL.

Thanks again guys!

------------------
Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 14* timing, 2 chamber flow's, and still workin' on the rest!

green94droptop · 05-17-2001, 05:10 PM

Quote:

Originally posted by dinomite:
Its a new car, i'd bet that your driving it kinda hard, and that would explain your mileage. I get about 17mpg all city, but if i am really reved up (sorry pun) after i fill it up, and heavy on hte gas, that can drop to 12 easy.

It's not really a new car...it just has 52k on it.

I haven't really gassed at all. It's been all city driving and not shifting past 2000rpm's. With an occassional spurt to 3500rpm's in first. BTW: always in 5th gear on the highways (45mph or above).

Just an update on the miles I have driven with this tank: I'm at 120 miles and just between 1/4 and 1/2 tank.

Thanks...sorry if this is too long

------------------
Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 14* timing, 2 chamber flow's, and still workin' on the rest!

green94droptop · 05-17-2001, 05:26 PM

Quote:

Originally posted by dinomite:
Its a new car, i'd bet that your driving it kinda hard, and that would explain your mileage. I get about 17mpg all city, but if i am really reved up (sorry pun) after i fill it up, and heavy on hte gas, that can drop to 12 easy.

It's not really a new car...it just has 52k on it.

I haven't really gassed at all. It's been all city driving and not shifting past 2000rpm's. With an occassional spurt to 3500rpm's in first. BTW: always in 5th gear on the highways (45mph or above).

Just an update on the miles I have driven with this tank: I'm at 120 miles and just between 1/4 and 1/2 tank.

Thanks...sorry if this is too long

------------------
Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 14* timing, 2 chamber flow's, and still workin' on the rest!

1BAD89 · 05-17-2001, 05:58 PM

I have an 89 GT with about 98k on it and if I take it easy , and take it up to 3 and shift, and maybe 1/4 of the miles on the highway I can get like 22-23 mpg it's awesome, but also when I used to drive hard most of the time I got like 11-12mpg, so it all depends on the way you drive. See ya.

------------------
3:55's,BBK Off-Road H-pipe,BBK jet-hot coated equal length shorty headers,BBK 70mm Throttle Body,BBK adjustable clutch quadrant,C & L 76mm Mass air meter,Cobra R's 17x9 w/ 245's,Trick Flow Intake,Flowmaster Force II exhaust system, Super Duty T5,Centerforce II Clutch,Heavy Duty Radiator,9mm Ford racing plug wires,Accel cap and Rotor

dinomite · 05-17-2001, 09:05 PM

THe only way to do gas mileage is to fill up all the way (the 87-93 stangs have a 15.4 gallon tank, yours should be the same), reset the trip, and drive. When you need gas, go fill up, look at how much it took (gal.) and then divide the number of miles on the trip by the gal. I usually get 200-220 on a tank if i drive nice, and thats 100% city sh1ty.

santora6 · 05-18-2001, 08:47 PM

Try adding friction modifier to your differential. I had the same mileage issue. As soon as I added the friction modifier my mileage increased from 14 to 19-20.

TEXSN95 · 05-18-2001, 08:57 PM

Quote:

Originally posted by santora6:
Try adding friction modifier to your differential. I had the same mileage issue. As soon as I added the friction modifier my mileage increased from 14 to 19-20.

Wow maybe I should try that...I've never heard of that before.

------------------
Clint L.
White 95 Cobra #3637
58cc GT40X heads with mild porting, Crane 2031 cam, FRPP 65 TB, 1.7s, Cobra intake, homeade cold air, 155lph, pullies, Tokico Illuminas, C springs, GW LCAs, Kenny Brown super subs, Steeda CC plates, aluminum driveshaft, Steeda quadrant, B&M ripper, Kirban FPR, MSD6A, Taylor wires, Mac shorties, off road hpipe, 2 1/2 ultra flows w/ dumps, R hood, Euro clear corners, stock 3.08s
13.61 @ 104.7 w/ 2.22

lx mike · 05-18-2001, 09:16 PM

Quote:

. As soon as I added the friction modifier my mileage increased from 14 to 19-20.

Amazing!! 5-6 mpg by just adding some friction modifier???

------------------
93-LX: 5 Speed, Flow's with H-Pipe, 3.73's Sub's and K&N.

green94droptop · 05-18-2001, 09:23 PM

Friction Modifier???? I have never ever heard of that? What is it? Where do I get it?
Do you think it will work in my case?

I have been reading the recalls on my car. It said that there was a difference in what Ford said the gas mileage would be on my 94 and what customers were getting.

Anyone heard?

That friction modifier sounds interesting!

------------------
Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 14* timing, 2 chamber flow's, and still workin' on the rest!

[This message has been edited by green94droptop (edited 05-18-2001).]

HKstang · 05-18-2001, 09:36 PM

Friction modifier is what you put in your posi diff to smooth out the engagement of the clutches. You're supposed to put friction modifier in whenever you change you diff fluid I believe. Mustangs should come with it from the factory.

05-19-2001, 07:05 PM

You might want to check your error codes for problems with your o2 sensors (or just look at them, though I really don't know how to tell). They monitor the air/fuel ratio, and if they are malfunctioning or not working at all ive heard the computer will act as if it's in "open loop" (how the engine runs when at WOT) which could lead to poor gas mileage if the ratio's not correct. I dont know if the SN95's are any different but on my '89 I just got a code about the sensors (I had a feeling they were bad) and I've been getting about the same mileage- 12 mpg- all city- whether I'm on it all the time or not (actually, mine seems to get worse when I try to keep it under 1800 rpm & drive like a granny, maybe my tranny's letting it stall too much?) anyways hope you figure it out, I'll probly have to drive my POS Datsun if gas $ keeps going up.

------------------

cad614 · 05-20-2001, 05:34 PM

I feel your pain. I have a 95 gt conv and have the exact same problem. I've done the same things you have, but I also get 12-14 mpg in the city and I've managed to get as high as 23 mpg on the highway. My gears are the factory 2.73s with an automatic tranny. Oh ya... the gas tank holds exactly 15.7 gal (I ran out of gas as I rolled into the station).

------------------
'95 GT Convertable

Unit 5302 · 05-21-2001, 12:21 AM

Fuel tanks expand slightly from usage. That's why you can get more than 6 gallons into a 6 gallon gas can.

You may have a bad temp sensor. Is your car warming up on the gauge when you drive? The O2 sensors as earlier mentioned could be a problem.

I have NEVER EVER gotten worse than 16mpg with my 87GT. Driving like a bat outta hell and in stop and go all week I've only recorded 16 once. That's in winter, in MN.

Accelerate fairly quickly, shift at 3000rpms, and don't use OD when you are travelling under 55-60mph.

StreetStang37 · 05-21-2001, 04:18 AM

I was getting about 13-13.5 mpg since Oct. (when I bought the car) and when I got the gears done and finally did a tune up, I now get 19 mpg (yes, corrected, not old 3.08 speedo reading). I should have done the tune up long ago! It had Bosch Platinums and now I have Autolite 24's and also got rid of the generico plug wires and got the MSD's.

------------------
1993 Mustang GT - March Ram Air & Pullies, K&N, C&L 73mm MAF, 3.73 Gears, Super Competition Hooker Headers, 2 1/2 in. High Flow H-Pipe & Cat Back, Pro 5.0 Shifter, 16* Timing Advance, 8.5mm MSD Plug Wires

05-16-2001, 11:07 PM	#1
green94droptop Registered Member Join Date: May 2001 Location: Central FL Posts: 59	really bad gas mileage??? Yo guys... I purchased a 94 gt conv with a 5 speed about 1 month ago. It has 50k miles on it and it runs perfectly. But what I didn't expect was this kind of gas mileage...12-13 miles to the gal. I went ahead and changed plugs (cold), wires (9mm FMS), cap/rotor (Accel), did a 180* thermo, and advanced the timing to 14. I thought I should get upto about 17-18 mi/gal. Filled 'er up the other day with 93 like always,(about 14 gallons) and now I'm at a half tank and have only driven about 90 miles. Now, I am babying the car right now; just regular city driving. When I checked out the old plugs (they looked like the original's), they were unbeleiveably gaped to .080. I went ahead and gaped the new accel cold plugs at .052 like Ford calls for. It runs a whole heck of a lot smoother. But the gas mileage is horrible. Any suggestions??? Thanks, guys! ------------------ Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180 thermo, 2 chamber flow's, 14* timing, and still workin' on the rest! [This message has been edited by green94droptop (edited 05-17-2001).]

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Gas mileage?	Nixon1	Windsor Power	17	08-07-2003 01:43 PM
Gas Mileage	Jacob_M	Blue Oval Lounge	5	01-28-2002 12:11 AM
bad mileage. Oxygen sensor?	Happy Trigger	Small Ponies	4	01-23-2002 11:58 AM
Gas mileage on a '78?!!	purple horse	Classic Mustangs	3	03-09-2000 01:07 AM
68 Mustang Gas Mileage?!	CobraAC	Classic Mustangs	3	10-23-1999 07:35 PM

05-17-2001, 11:20 AM	#2
slo95 Registered Member Join Date: Dec 2000 Posts: 168	think the previous owner put gears in it? sounds about like what i get in my 95 vert with 3.73's. about 15 city / 19 highway, but I like the gas pedal...

05-17-2001, 12:12 PM	#3
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	The fuel gauge is not linear so I wouldn't base your calculations on that. You may also want to verify that your speedometer, and, therefore, your odometer are accurate. 90 does seem low, though, for half a tank. I'm at like 110 or so with my engine and 3.55 gears. Gears would not make that much a difference. ------------------ 351W 89 Mustang GT Convertible

05-17-2001, 12:34 PM	#4
lx mike Undescribable Join Date: Sep 1998 Location: Ft Myers Fla Posts: 1,539	wait till you need gas to see how far you go then you can see what your mileage is, some cars the needle moves faster from full to half than it does from half to empty, run it down as far as u feel comfortable with then fill it back up and figure your mileage from there. ------------------ 93-LX: 5 Speed, Flow's with H-Pipe, 3.73's Sub's and K&N.

05-17-2001, 03:33 PM	#5
Jerm95gt Registered Member Join Date: May 2001 Location: martinez,california,USA Posts: 12	i drive around hmmm lets say 20 miles a day?5 days a week and i fill up at least once a week....you notice a real difference if u rev it high or not....i came up with the plan i try to follow which is reving low and not driving to fast mon-thurs and on friday+weekend i race some and rev it incredibly high....if i rev high during the weekend i can kill about 3/4 tank.You should be able to get like 15mpg max city driving...the highest you can get is 17 what ford says and i know thats a joke.ps: doesn't the car ask for 87? buy 87 and save some cash

05-17-2001, 05:02 PM	#6
dinomite The Dude Join Date: Feb 2001 Location: Arlington, VA Posts: 1,262	Its a new car, i'd bet that your driving it kinda hard, and that would explain your mileage. I get about 17mpg all city, but if i am really reved up (sorry pun) after i fill it up, and heavy on hte gas, that can drop to 12 easy.

05-17-2001, 05:03 PM	#7
green94droptop Registered Member Join Date: May 2001 Location: Central FL Posts: 59	Thanks guys... This is the first tank I have put in since the tune up. I don't think the previous owner had put gears in it. They seem like their 3.08's. And as far as the gas gauge being acurate, there is no way to really tell, or is there? Jerm95gt: I advanced my timing when I did the tune up. I put it at 14deg and I know if I put anything less than 93 in it pings. And it pings on really really hot days here in FL. Thanks again guys! ------------------ Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 14* timing, 2 chamber flow's, and still workin' on the rest!

05-17-2001, 05:58 PM	#10
1BAD89 Tubbed and Juiced Join Date: Mar 2001 Location: Tulsa, Oklahoma Posts: 1,861	I have an 89 GT with about 98k on it and if I take it easy , and take it up to 3 and shift, and maybe 1/4 of the miles on the highway I can get like 22-23 mpg it's awesome, but also when I used to drive hard most of the time I got like 11-12mpg, so it all depends on the way you drive. See ya. ------------------ 3:55's,BBK Off-Road H-pipe,BBK jet-hot coated equal length shorty headers,BBK 70mm Throttle Body,BBK adjustable clutch quadrant,C & L 76mm Mass air meter,Cobra R's 17x9 w/ 245's,Trick Flow Intake,Flowmaster Force II exhaust system, Super Duty T5,Centerforce II Clutch,Heavy Duty Radiator,9mm Ford racing plug wires,Accel cap and Rotor

05-17-2001, 09:05 PM	#11
dinomite The Dude Join Date: Feb 2001 Location: Arlington, VA Posts: 1,262	THe only way to do gas mileage is to fill up all the way (the 87-93 stangs have a 15.4 gallon tank, yours should be the same), reset the trip, and drive. When you need gas, go fill up, look at how much it took (gal.) and then divide the number of miles on the trip by the gal. I usually get 200-220 on a tank if i drive nice, and thats 100% city sh1ty.

05-18-2001, 08:47 PM	#12
santora6 Registered Member Join Date: May 2001 Posts: 1	Try adding friction modifier to your differential. I had the same mileage issue. As soon as I added the friction modifier my mileage increased from 14 to 19-20.

05-18-2001, 09:23 PM	#15
green94droptop Registered Member Join Date: May 2001 Location: Central FL Posts: 59	Friction Modifier???? I have never ever heard of that? What is it? Where do I get it? Do you think it will work in my case? I have been reading the recalls on my car. It said that there was a difference in what Ford said the gas mileage would be on my 94 and what customers were getting. Anyone heard? That friction modifier sounds interesting! ------------------ Green '94 GT conv. -- K&N filter charger, FMS 9mm wires, Accel hipo cap/rotor, 180* thermo, 14* timing, 2 chamber flow's, and still workin' on the rest! [This message has been edited by green94droptop (edited 05-18-2001).]

05-18-2001, 09:36 PM	#16
HKstang Registered Member Join Date: Feb 2001 Location: Toronto Canada Posts: 44	Friction modifier is what you put in your posi diff to smooth out the engagement of the clutches. You're supposed to put friction modifier in whenever you change you diff fluid I believe. Mustangs should come with it from the factory.

05-19-2001, 07:05 PM	#17
Big&bad89rag Guest Posts: n/a	You might want to check your error codes for problems with your o2 sensors (or just look at them, though I really don't know how to tell). They monitor the air/fuel ratio, and if they are malfunctioning or not working at all ive heard the computer will act as if it's in "open loop" (how the engine runs when at WOT) which could lead to poor gas mileage if the ratio's not correct. I dont know if the SN95's are any different but on my '89 I just got a code about the sensors (I had a feeling they were bad) and I've been getting about the same mileage- 12 mpg- all city- whether I'm on it all the time or not (actually, mine seems to get worse when I try to keep it under 1800 rpm & drive like a granny, maybe my tranny's letting it stall too much?) anyways hope you figure it out, I'll probly have to drive my POS Datsun if gas $ keeps going up. ------------------

05-20-2001, 05:34 PM	#18
cad614 Senior Member Join Date: Apr 1999 Location: San Angelo, TX Posts: 377	I feel your pain. I have a 95 gt conv and have the exact same problem. I've done the same things you have, but I also get 12-14 mpg in the city and I've managed to get as high as 23 mpg on the highway. My gears are the factory 2.73s with an automatic tranny. Oh ya... the gas tank holds exactly 15.7 gal (I ran out of gas as I rolled into the station). ------------------ '95 GT Convertable

05-21-2001, 12:21 AM	#19
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Fuel tanks expand slightly from usage. That's why you can get more than 6 gallons into a 6 gallon gas can. You may have a bad temp sensor. Is your car warming up on the gauge when you drive? The O2 sensors as earlier mentioned could be a problem. I have NEVER EVER gotten worse than 16mpg with my 87GT. Driving like a bat outta hell and in stop and go all week I've only recorded 16 once. That's in winter, in MN. Accelerate fairly quickly, shift at 3000rpms, and don't use OD when you are travelling under 55-60mph.

05-21-2001, 04:18 AM	#20
StreetStang37 Registered Member Join Date: Dec 2000 Location: San Jose, California USA Posts: 275	I was getting about 13-13.5 mpg since Oct. (when I bought the car) and when I got the gears done and finally did a tune up, I now get 19 mpg (yes, corrected, not old 3.08 speedo reading). I should have done the tune up long ago! It had Bosch Platinums and now I have Autolite 24's and also got rid of the generico plug wires and got the MSD's. ------------------ 1993 Mustang GT - March Ram Air & Pullies, K&N, C&L 73mm MAF, 3.73 Gears, Super Competition Hooker Headers, 2 1/2 in. High Flow H-Pipe & Cat Back, Pro 5.0 Shifter, 16* Timing Advance, 8.5mm MSD Plug Wires