crappy gas mileage

[tehnick]

I have been trying to figure out why I have been getting poor gas mileage. My car is about 1,500 miles short of 60K and with gas prices being what they are I am not getting into the throttle. I am shifting around 2000-2500 RPMs and am not sure what else I can really do.

I fill my car up at Chevron and only Chevron so the quality of gas shouldn't be an issue. I make sure I keep up on maintenance but know the 60K mark is around the corner and will be taking the car in ASAP for the 60K mark maintenance.

I am just over half a tank right now and the trip odometer says I have gone just under 100 miles. I believe my tank is 15.7 gallons so that puts me at just under 13 miles a gallon on the 87 octane juice in the car. These are city miles, not highway. I haven't been able to see what I get in terms of highway miles in a while because I haven't left town for quite some time. I will be driving to Bend and back on June 2nd though to visit family.

Any ideas on things I can do to narrow this down?

 

[GT_4_FUN]

I have a Honda Civic I would sell you. It gets over 40MPG. With it and your Mustang, you would average 27MPG.

 

[agirlbeatyou]

A guy on the radio said this morning that he put premium in his car at 6 % higher in price then the 87 octane, however he got 20 % more mileage out of the car.

Im going to try it on my next tank. Ill let ya know. Im getting 280-300 miles on a 24 gallon tank at the 87 octane. I just filled up yesterday (87 octane) so give me a week or 2 Ill let ya know the outcome.

 

[tehnick]

A guy on the radio said this morning that he put premium in his car at 6 % higher in price then the 87 octane, however he got 20 % more mileage out of the car.

Im going to try it on my next tank. Ill let ya know. Im getting 280-300 miles on a 24 gallon tank at the 87 octane. I just filled up yesterday (87 octane) so give me a week or 2 Ill let ya know the outcome.

I'll wait with anticipation. 6% extra for 20% extra sounds good to me, but I know things will vary such as automatic or manual transmission, weight, blah blah blah.

Thanks Misha

 

[WANNA_BE_GT]

A guy on the radio said this morning that he put premium in his car at 6 % higher in price then the 87 octane, however he got 20 % more mileage out of the car.

Im going to try it on my next tank. Ill let ya know. Im getting 280-300 miles on a 24 gallon tank at the 87 octane. I just filled up yesterday (87 octane) so give me a week or 2 Ill let ya know the outcome.

I agree with Misha. Use higher octane fuel.

 

[SMOKEDYA]

I'm gonna push the B.S button on the higher oct thing ! peace



john

 

[SMOKEDYA]

Um my 4 cyl is doing preatty good on milage even with it running crappy and leaking gas tank! peace



john

 

[tehnick]

I agree with Misha. Use higher octane fuel.

Just always felt that it's just a V6 and not a performance car so I never saw a need for higher octane fuel. I might fill it with premium next time just to see if there is a difference.

 

[Bullitt347]

I'm gonna push the B.S button on the higher oct thing ! peace



john

I agree on this except for the following condition: engine "pings" or detonates on the 87 octane fuel and the PCM detects this and pulls timing to prevent detonation, which would hurt mileage because of the loss of ignition lead. Even if you do not hear the detonation does not mean it is not there. In that case the higher octane fuel would help mileage, otherwise a waste of $'s

 

[Rootus]

I'm gonna push the B.S button on the higher oct thing

Me too. If anything, I'd expect higher octane to reduce mileage slightly.

Few (if any) Mustangs have knock sensors, and even then, if it were going to knock it wouldn't be while cruising down the freeway at 2000 RPM.

tehnick -- guessing your mileage by looking at the gauge is a losing proposition. I'd check it fill-up to fill-up several times and average that out for a more accurate number.

 

[duner]

Maybe the O2 sensors are crapping out.

 

[Juiced87Notch]

Maybe the O2 sensors are crapping out.

have you changed the fuel filter lately?

 

[Bullitt347]

Me too. If anything, I'd expect higher octane to reduce mileage slightly.

Few (if any) Mustangs have knock sensors, and even then, if it were going to knock it wouldn't be while cruising down the freeway at 2000 RPM.

tehnick -- guessing your mileage by looking at the gauge is a losing proposition. I'd check it fill-up to fill-up several times and average that out for a more accurate number.

True not ALL Mustangs have knock sensors, BUT the 32 valve engines do, as well as the Supercharged Mustangs. My error in not checking what Mustang we were talking about. Sorry about that.

 

[fastang2k1]

Nick,

Is the car running any different than normal? You can't say that you haven't been putting your foot in it cuz a bunch of us saw you get on it at the Starbucks a couple of weekends ago. LOL. At least you could have done a burnout to show what the ricers are missing. But back on the issue of gas mileage, check your plugs, wires, o2 sensor, tire pressure, run a higher octane, go to the parts store and pick up a bottle of octane booster/fuel saver/injector cleaner and see if this helps. Also if you do a lot of stop and go, hurry up and wait, driving all over in circles,type of driving, then you will notice your gauge sinking towards the "E" faster.

~B~

 

[Scooby5.0Doo]

a thermostat thats easy to open or stuck open will keep the car in warm up enrichment. my bmw was ave 24 per tank then the thermostat went bad and went down to 18. also low air pressure in the tires can cause poor gas milage my 5.0 saw a 4 mpg increase going from 30 to 35 in all tires.

 

[Rootus]

True not ALL Mustangs have knock sensors, BUT the 32 valve engines do, as well as the Supercharged Mustangs. My error in not checking what Mustang we were talking about. Sorry about that.

AFAIK only the N/A 32v modulars had knock sensors. My '03 Cobra definitely did not. Rumor was that the noise from the blower made the false positive rate too high. Also, I'm not sure about the new 3V creatures, I have no experience with them, but with the other fancy doo-dads maybe they have the sensor.

 

[Rootus]

a thermostat thats easy to open or stuck open will keep the car in warm up enrichment. my bmw was ave 24 per tank then the thermostat went bad and went down to 18. also low air pressure in the tires can cause poor gas milage my 5.0 saw a 4 mpg increase going from 30 to 35 in all tires.

I'd bet that cold enrichment turns off at 130* or so. That's about where it was on my 5.0 (been too long since I had the tweecer, so I can no longer remember what the exact value is ... but I remember being surprised about how low it was).

The more I think about it, the more I lean towards O2 sensors. They're going to be critical to gas mileage... if they're not accurately indicating stoich it could get pretty ugly.

 

[Scooby5.0Doo]

I'd bet that cold enrichment turns off at 130* or so. That's about where it was on my 5.0 (been too long since I had the tweecer, so I can no longer remember what the exact value is ... but I remember being surprised about how low it was).

The more I think about it, the more I lean towards O2 sensors. They're going to be critical to gas mileage... if they're not accurately indicating stoich it could get pretty ugly.

Hmm my 88 gt runs enrichment untill 180 thats why i could not run a 178 t stat and my bmw is like185 gauge in the bmw was right where it was supose to be but when i hooked a scanner to it and read out the temp it was about 15* below normal.

 

[ASD]

Nick,

Is the car running any different than normal? You can't say that you haven't been putting your foot in it cuz a bunch of us saw you get on it at the Starbucks a couple of weekends ago. LOL. At least you could have done a burnout to show what the ricers are missing. But back on the issue of gas mileage, check your plugs, wires, o2 sensor, tire pressure, run a higher octane, go to the parts store and pick up a bottle of octane booster/fuel saver/injector cleaner and see if this helps. Also if you do a lot of stop and go, hurry up and wait, driving all over in circles,type of driving, then you will notice your gauge sinking towards the "E" faster.

~B~

Yeah what the hell was that half drift/burnout thing you did when you went through SB? I would say your gas mileage is just about right from the way you drove that night. Next time stop by and say hi.

 

[fhinesley]

Curious

What would you expect a stock 2004 GT vert(just flowmasters) running chevron supreme, well maintaned, with 34k miles on it, mostly city driving, to get for gas mileage?