Bad GT fuel milage.

[Bryan]

Hey y'all,I have a question reguarding fuel milage on the Pontiac Vibe GT. Mine currently has about 3500 miles on it and I've consistantly been getting 27 to 29 MPG with mixed driving. When I had my oil change, I put in a container of Chevron Techron Fuel System Cleaner. Since then, my milage has dropped alarmingly. I am down to 22 to 24 mpg. I do have a Yakama bike rack on top of my car which is empty most of the time. But even with that on, I didn't notice much of a change in mpg...that is until I put the fuel system cleaner in. Is it possible that my fuel filter is dirty? What should I do? Thanks for your help.

[Bryan]

As an experiment, I removed all of my bike rack and reset the computer by disconnecting the negative battery terminal lead. I'll see if there is an improvement.Oh, and by the way, durring my oil change I had the dealer adjust my steering wheel and parking brake. I only needed the steering wheel adjusted but they went ahead and did a whole alignment and toe reset. Could this poor mpg be caused by these adjustments? Should I take my car back to the dealer?

[joatmon]

Incorrect alignment can definitely have an effect on gas mileage. Also, when they adjusted the parking brake, if they made it too tight so that it dragged all the time that could be a factor too. I wouldn't think the fuel filter was a problem because they are intended to be a really long time between replacements, and you have low miles on your car, so the techron cleaner shouldn't have found much to clean or kick loose in the tank. I don't know what to tell you to try, but it's is a big % drop. There are so many things that can affect gas mileage, but if the drop really did coincide with your service visit to the dealer, then it seems that something that happened that day would be the likely cause.

[StampedeVibe]

I've got an 03 Vibe GT, and I've noticed that when it gets cold out, I get a huge drop in mileage. Granted, cold up here is a very different cold down there. This may just be pertinent to me, but when I got out of my breaking in period, I hit lift with my Vibe farily regularly, which has a disasterous effect on your mileage.

[Bryan]

I talked to my friend and he owns a VW Jetta. He says his milage has been crappy too. I guess it might be a bad batch of gas in town. But just to be on the safe side, I'm going to make an appointment at the dealer. Thanks to all for the advice.

[soldierguy]

A lot of places switch to "winter gas" around October-December, depending on the area. Usually there will be a sign or a sticker near the pump saying the gas is oxygenated...don't know what that means in terms of the content of the gas, but the result is supposed to be reduced emissions...has something to do with the ozone layer and wintertime...I don't know all the details, but it is specific to wintertime emissions. A side effect of the gas is reduced power and poorer mileage. Where my parents live in CA they switch in November, and Dad always notices gas less gas mileage and less performance...his mileage usually gets worse by around 10%.

[AKLGT]

Quote, originally posted by StampedeVibe »I've got an 03 Vibe GT, and I've noticed that when it gets cold out, I get a huge drop in mileage. Granted, cold up here is a very different cold down there. This may just be pertinent to me, but when I got out of my breaking in period, I hit lift with my Vibe farily regularly, which has a disasterous effect on your mileage.yes, my mileage goes down in the winter time due to using the heat, power on everything, etc. but still i usually get about 24-26 mpg opposed to the normal 28 mpg. and that's with hitting lift just about every other day.

[thorntcl]

Hey Bryan,How did you reset your computer? I've left my negative connection off for hours (and hit the brakes according to another thread on resetting the computer).When I turn on my car all my radio presets are still there which leads me to believe that I have not reset my computer. Do you know what else has to happen to reset the computer or was it reset after I left off the negative connection.I too am trying to figure out my terrible gas mileage on my 04 fwd basic vibe. I've never been able to get better than 28 cdn mpg or 10 L/100km or 23 US mpg... or ~500km (300 miles) a tank...

[ragingfish]

Resetting the computer requires disconnecting the negative battery cable for about a minute.The stock radios store station presets indefinitely...I removed my stock radio from my car last year...hooked it up the other day for kicks, it still had the presets.The easiest way to determine a system reset is if you have a check engine light. When you disconnect the battery and reconnect it, the light will be out, but if the problem exists, will come back on.

[Bryan]

thorntcl,If you disconnect the negative power lead from your battery, you will reset your ecu. Just be sure to leave it disconnected for at least a minute. As far as the radio, it like the odometer, has some sort of battery back-up. When I did this procedure on my Vibe, my presets were still there but I had to reset my clock. Also, I let my car idle for 10 minutes. Based on experience with my last truck, if you didn't let it idle for that amount of time after a disconnecting the battery, it would take FOREVER for the ecu to learn how to idle right. I don't know if the Vibe is this way but I didn't want to take a chance.

[thorntcl]

Thanks ragingfish, that answers my concerns.Now to figure out if resetting it will help my fuel economy.No check engine light has ever come on so I'm trying to troubleshoot things on my own. Lots of ideas here to help me figure out what it might be. (bad alignment, bad plugs, clogged catalyct - which might not show up on the computer read outs...)I may resort to have a pollution check done on the car, it costs ~ $35, but may be the ammunition I need for the dealer to take me seriously...

[thorntcl]

Thanks Bryan,I'll leave my car run 10 minutes tomorrow morning I might get better gas mileage yet...

[ragingfish]

I'd advise disconnecting the battery once again to ensure the CPU is reset prior to it's "relearning."

[DavidPIL]

Hi Bryan...Same thing happened to me. I had been driving all over Ohio, Ky, TN the last month or so. Getting 30-32 mpg easily... Came back from Ohio 2 weekends ago, filled up at a different gas station. I usually get 120-135 miles between full and a quarter, barely got 80, at the half I was close to 150, usually get over 200.... closing in on around 230 for the 3/4 mark. Usually around 300. I'm assuming it's the oxygenated gas but I'm going to let this tank run out as much as possible then go to my usual station. Went to a BP I had never gone to before, usually go to Marathon.Had changed nothing on the car though I did my own oil change before going to Ohio. I dunno...Dave

[Dezz1]

Simple Answer. When the weather becomes cooler our mpg drops. At cooler temperatures vehicles produce more HP and Torque. As a result, it burns more gasoline, at lets say 3200 RPM, when it is cooler, compared to when the temperature is warmer, running at the same 3200 RPM's. CAI, Cold Air Intake is nothing more than a tube with a filter on it that protrudes to the car's underside so that your engine can suck up cooler air, which burns in the engine block more effectively than warm air. Therefore, to a limitation, the cooler the air, the more HP, as a result, the consumption of more gasoline.

[Bryan]

Well, I've finally come to a conclusion. The GT engine is VERY tempermental about fuel additives. Shortly before I got to 6000 miles, my mileage went back to upper twentys with in-city driving. When I did my second oil change, I put another bottle of fuel system cleaner in when I got fuel. Same thing happened. My mileage hit the floor. Not even disconnecting the battery would correct the issue. I'm now approaching 9000 miles and my mileage has gone back up to upper twentys. My advise, use good fuel such as Chevron or Mobil and stay away from fuel additives! Weird!

[champcaracing]

Quote, originally posted by trdvibe »yes, my mileage goes down in the winter time due to using the heat, power on everything, etc. but still i usually get about 24-26 mpg opposed to the normal 28 mpg. and that's with hitting lift just about every other day. hope you hit lift every OTHER day??, damn, i'm in lift as soon as i'm on the main street and as much as i can on the way to and from work....