njsharkracer

I wonder if my driving habits are killing my fuel milage. I am averaging 21-24mpg per tankful. The CEL is not on, but I wonder if the O2 sensors ae just going bad and haven't tripped the light as of yet. If so I wonder if one of those additives at advance auto parts will clean them up.

Anywho, most of my driving is done in a combination of city and highway, 60/40 would be my educated guess. Most of the time when I start from a dead stop I always rev up to about 3k rpm and then shift up to the next gear. Now after I get into 3rd, sometimes traffic will not allow me to speed up the way I want to and I end up just dumping into 5th after I hit 3k in 3rd gear.

I have also tried always shifting at 2k rpm in each and every gear for a tankful and that amounted to about 1mpg increase, hardly an improvement and could just be flux in mpg from tank to tank.

I don't usually floor it, I'm more of a half-pedal type of person. Anyone have any ideas?

DTN

You should not launch from 3KRPM. That's hard on the clutch. You should be shooting off the line like that. That's how you should take off on a drag strip mang!

You need to get the CEL fixed. Your car is suffering becasue there is a problem. A CEL is not something you can ignore. You do not get a CEL when the horn DB is not at optimum, the washer fluid is low, or your spare tire is missing. This is because the car can run just fine without those things running right. A CEL says "hey dummy, I've got a problem and you need to fix me before something really bad happens!"

edit: you said NO cel! oops! Check the resistance on the plug wires, they should not exceed 10,000 ohms/foot. Also, check your spark plug gap.

If you are not a "floor it" type of person, you're probly due for some maintenance, because a 3K launch should be a pretty good off-the-line launch.

brian01tib

He said the CEL isnt on. It could be the traffic possibly start and stop would kill your gas milage if your reving to 3k everytime. The A/C also hurts your gas milage so if you leave it off you'll get better milage that way.

DTN

^^ I know, I typed the edit as you were reading.

... wait a minute... Didn't you JUST replace the wheel bearing earlier this week? Have you had time to go through a tank yet? A wheel bearing can make it much more difficult for the weel to turn.

Ericy321

Wheel bearing shouldnt make a difference. Maybe a small one but not noticeable. And he doesnt launch at 3k. Thats when he shifts.

I would suggest doing a basic tuneup on it. Plugs, wires, check your air filter. Maybe run some seafoam and have your injectors cleaned. (Not with gas additive, by a shop)

PRD Wires are the way to go. I also have some for sale right now. I would definately recomend them for looks and performance.

tdonnell

I would say 3000 rpm is the normal daily shift point if you are trying to achieve good fuel mileage.

If I baby my 2.0L 5spd. I can get over 30 mpg average per tank.

Usually it is between 26 and 28 though.

Tune up sounds like a good place to start, also check your brakes and make sure there is no uneven rotor or pad wear. If one wheel gets significantly more dust on it than the others, that is a hint that the brakes are dragging.

njsharkracer

tdonnel:

actually it's quite funny about the brake dust. both of my rear wheels get covered very easily with dust while the front ones are fine. Now before you jump to conculsions, let me tell you about what i did recently.

I tried to change the rear brake pads, as the rotors looked fine and were still smooth. well i've only done front calipers before, and i mistakenly took a c-clamp to the rear calipers instead of getting the tool to spin the piston back into the rear calipers. so they still brake, and the e-brake still works, but i know i've done some damage to the calipers from my ignorance. Also I wonder if the dust is also being created by the pads themselves, as they are the cheap 19.99 pads from advance auto. I know, i need to get better pads, but it was all the money i had at the time and i didn't want the old pads ruining the rotors.

I don't think the rear calipers are dragging at all since they don't over heat up in regular driving and braking. And yes I just got the wheel bearing changed earlier this week, but this mpg issue has been going on for a bit. It did jump from 21-27mpg for one tank full when i reset the ecu, but then the next tank was back to the 21mpg area. And no, i rev up up to 3k rpm in 1st, not launch at 3k rpm from a dead stop. I'd have no clutch in a week if i did that. I usually always launch around 1200-1500rpm.

I actually changed the plug with new plugs gapped correctly about 2 months ago, and the wires looked relatively new from when I bought the car this past summer, so I kept on using them.

Puzzling, but thanks everyone.

Mad-Machine

where abouts in South Jersey are you anyway? My Bimmer, which can easily hit 35 on the highway, usually drops down to about 26/27 just running back and forth to Atlantic City everyday. I have also noticed in the past two weeks since it got really cold, my miliage has dropped way off.. down into the low 20s (24 according to the on board computer) so it may be a combination of the cold, where you get your gas, and whatever it is they put into winter formula gas..

njsharkracer

i completely forgot about the winter gas. That could account for some of the loss of mpg. I live in riverside, nj.

Also, i keep on forgetting to mention that my stock exhaust manifold has become cracked in the last 2 months. Not a major crack, but visible and you can hear it enough to know it's a crack.

Ericy321

Well, you should be able to get that replaced I think. Start there. Then I would go for a tune up for sure. Cant hurt