GenVibe - Community for Pontiac Vibe Enthusiasts

Hey all. Newish vibe owner here... Been searching all over this awesome forum for tips and places to check in regards to my girlfriend's 04 vibe fwd. On average she's getting about 20-23mpg (mainly city driving) ever since she started driving the car in July. So I've searched tho forum for some ideas and well here's what I've done..

1) new ngk irridum plugs
2) upper and lower o2 sensors
3) cleaned intake manifold & idle valve (I think that's what its called lol)
4) cleaned maf
5) changed air filtre
6) changed oil & filtre
7) checked tire psi
8) disconnected the AC evap electronic plug (as for some reason the car would always engage the AC pump no matter what temperature when on both defrost modes) and put on a dummy plug to hopefully keep the AC working for the summer
9) new pcv valve
10) replaced was tank as it started leaking hah
11) no brake drag as checked that this past weekend when the fuel tank was changed

Anything else I can do to try and get better mpg? I know the car has high miles on it (325k) so that too could very well be the main issue. The car has plenty of power and starts & idles fine. So I'm left slightly puzzled...

Any check engine lights?
Does the driver have a reputation for getting poor gas mileage?
How did you calculate gas mileage?

Sounds like you've taken care of everything mechanical at this point, it's probably going to come down to driving style.

That's the thing zero check engine lights. She is a new driver so it could be her foot causing it. I thought it was perhaps the crappy gpower plugs that we put in the car causing the issue but switching to the irridum plugs just seem to give more power vs fuel economy.

I was under the car on the weekend with it running and I did notice there was a decent amount of air blowing in my face near where the downpipe is, close to where the ending and tranny meet, but it didn't smell like exhaust. That being said, I think there is a leak in the exhaust manifold, as I didn't feel any hit air escaping out of the downpipe.

Sorry for making a new topic on this just didn't know if I overlooked anything when I was doing my research.

Also my mistake its a 04 vs 03 not that its a big difference

A manifold leak would make a loud ticking noise.
The air you felt might just be air rushing around the pulleys and serpentine belt.
I don't see a new thermostat on your list.
A sticky thermostat can keep the engine from fully warming up.
I recommend only an OEM 'stat; and a new radiator cap while you're at it.
The AC working in defrost is normal.

If you're really concerned, trade cars for a week and compare mileage. You'll probably find it's caused by driving style.

Hah I would trade cars for a week however my car is 6spd hers it auto...

As for the thermostat the car seems to be getting up to proper engine temperature. Would for sure show right now with the cooler temperatures out.

On average she's getting about 20-23mpg (mainly city driving)

That does not seem excessive if there are a lot of cold starts involved. If I drive my Vibe (base, auto) short distances in town only I often get 26-ish mpg (US gal). I'd say that the additional weight and friction of the AWD can account for at least 2 mpg of lower yield and the rest is driving style.

Observe her driving (don't say anything ). If she brakes hard and frequently she is wasting fuel. She can save fuel by looking 2 to 4 cars in front of her and reacting to them rather than the one immediately in front of her. If she anticipates traffic light timing she won't have to step on the brakes as often. She will be coasting frequently and thus save fuel.

The air you felt is likely the flywheel. There is an opening there to check for a main seal leak and to unscrew the pressure plate bolts when removing the trans from the engine.

I have that same air blowing in my 05 awd vibe.

For just city driving, especially short trips that is somewhat normal, especially if she excellerates relatively faster.

Tbh, I've been surprised at how inefficient the awd vibe is. That said I have only ever owned sub compact front wheel drives. My Toyota Vios with full bolt ons that gets driven very hard average 6L/100 km (a lot of highway). My Vibe as much as myself and my wife love it, with about 60/40 city/highway and not driven hard averages 10L/100km. For a non full time awd indeed that is fairly poor, especially since it is only a 1.8L engine

Fill up the tank, hit the highway and stick to the speed limit for an hour or two. Then fill up again and do the math. I bet she easily surpasses 30MPG. City driving kills MPG.

There are apps which use the accelerometers in cell phones to critique driving style, if that is an issue. https://play.google.com/store/apps/deta ... urve&hl=en

Kwalsh24 wrote: 8) disconnected the AC evap electronic plug (as for some reason the car would always engage the AC pump no matter what temperature when on both defrost modes) and put on a dummy plug to hopefully keep the AC working for the summer

I don't know about the evap electronic plug, but perhaps a better way would be to disconnect the electrical wire behind the climate controls that automatically engages the AC when in either half or full defrost. All that does is prevent the auto AC in those positions, and the AC is available anytime using the AC button. I don't have a picture of it handy, but I remember it being a small connector with only two wires that plugs in behind the air direction control rotary switch. Easy enough to get to if you pull the radio


I know my gas mileage drops in the winter, and it has also dropped since it became impossible to find gas that wasn't 10% ethanol

viewtopic.php?f=17&t=6088&#p65128 has an excerpt from the 03 factory service manual on what to check for poor gas mileage