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06 Maxx SS MPG

4655 Views 28 Replies 8 Participants Last post by  Alan06
My 2006 Malibu Maxx SS (3.9L V6) is averaging 13.67 mpg. My last fill up was 11.6 mpg!
I purchased this vehicle a month ago and track my mileage on every fill up. This is not the information coming from the computer, these are my calculations based on miles driven between fill ups.
I replaced the EVAP purge valve and got a new gas cap after a code. The CEL hasn't gone off since.

Any ideas on why the vehicle is getting HORRIBLE gas mileage?
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Oil smell coming in the vents , is usually someone spillled a little oil on top up or change....if thats not the case
Here we go......
You are leaking oil ...its running on the manifold somehow. You changes the evap solenoid....was this hecause you have a code saying vacuum problem? I am guessing possible gasket faliure hense the oil leak....and the smell of oil... it can contribute to bad milage aswell....... this is a guess ,but with your symptoms it makes sense
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And when reading the codes, write down the actual codes and share them here. That will be very helpful to our members who are really good with these things.
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What are "potential" ussues withe EVAP and O2 sensors? I suggest you take care of the EVAP problems first.
I'm not sure at this point. I have replaced the EVAP solenoid/valve (at manifold) and upstream 02 sensor.
Can anyone help me with the location of the Vapor Canister on a 2006 Maxx SS (3.9L)?
I've looked around the rear wheel wells and don't see anything that resembles it. I thought I'd seen somewhere else that it is tucked above the gas tank and that the tank needs to be lowered to get to it? Does anyone know if this is the case? If so, is it a DIY project or do I need to fork out the labor $$?
Fuel economy is suffering and I've pretty much gone down the checklist and replaced O2 sensors, sparks and plugs, cleaned throttle body and MAF, cleaned fuel injectors ...
Cannister is in the bottom right of both of these photos, passenger side, forward end of tank. Photos are from a 2006 LS, not an SS.


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Good photo ,nice to know
Cannister is in the bottom right of both of these photos, passenger side, forward end of tank. Photos are from a 2006 LS, not an SS.
Thank you! Do you know if they can be gotten to w/o lowering the tank?
I cannot say as I removed the entire tank to change the fuel level sender. I would say that if you removed the right side tank strap and loosed the left side, the tank should hang down enough to access what you want without totally removing the tank.
When I removed the gas tank from my car, I found the hard part was dealing with jacking the car high enough, laying on the ground, working upside down and supporing the tank. Fasteners and electrical connections and fuel line connectors all seperated easily. If you have the time I don't see it as a hard job. You want the tank almost empty to do this job. You can use the car's fuel pump to empty the contents into a jerry can via the fuel rail.

Be sure you are replacing the correct part. Perhaps you have some other problem that can only be seen by dropping the tank entirely.
Before doing heavy stuff, like removing the gas tank, I recommend looking at the easy stuff. For example:
1) Jack up the wheels and try to spin them by hand. Could there be a seized/rusted caliper that is preventing a wheel from spinning easily? Pay special attention to the rear wheels, to be sure your parking brake isn't always engaged.
2) Is your transmission shifting through all four gears? Are you sure you aren't limited to just two or three gears when you drive?
3) Are you sure the transmission fluid is at the proper level? When is the last time the transmission's filter and fluid were changed?
4) You've already changed some parts. Using your code-reader, erase the codes, then start fresh, so you know you aren't looking at old codes from before the parts-changes. After driving around for awhile, and the engine is nice and hot, check the codes again and see if anything new showed up. Then let us know exactly what error-code numbers you're getting.

For reference, my SS Maxx gets 18 mpg city and 23 mpg highway. I reset it to zero each time I fill up and it's usually around 21.5 mpg by the time I fill up again.
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