bad gas milage

**wilder9032** · 02-28-2011

my 06 grand prix is only getting average on the computer 17.7mpg is that normal? what could I do to get it better just cleaned the mas. it is the 3.8 liter base model

**brandonl2000** · 02-28-2011

thats about right if u drive some city miles in there. and plus the weather might still be cold where you are. and winter gas.
also make sure you're up to date on a tune up.

and fyi, my car gets 17.7 too so no worries

**wilder9032** · 03-01-2011

ok great yeah im in buffalo ny so its been real cold the last four months. I just did a tune up before winter. thank you

**copperpacecar** · 03-01-2011

plus did you clock your mileage using the tach and the amount of fuel put in or did you use the mpg on the instrument cluster as that thing can be terribly inaccurate...use miles divided by gallons and see if its the same

**brandonl2000** · 03-01-2011

Originally Posted by copperpacecar

plus did you clock your mileage using the tach and the amount of fuel put in or did you use the mpg on the instrument cluster as that thing can be terribly inaccurate...use miles divided by gallons and see if its the same

either way i get the same number. my dic tends to be correct most of the time.

**SlowNA06** · 03-01-2011

Originally Posted by wilder9032

my 06 grand prix is only getting average on the computer 17.7mpg is that normal? what could I do to get it better just cleaned the mas. it is the 3.8 liter base model

When my '06 hit 70k, I was getting similar mileage. I cleaned the MAF, throttlebody, and replaced the sparkplugs. It now gets 26-28mpg. Always reset your average when you fill your tank so you can monitor it properly.

**2002gtx** · 03-01-2011

should be better than that, my 02 gtx i got 23.7 on my way home from NJ last week

**wilder9032** · 03-10-2011

Originally Posted by SlowNA06

When my '06 hit 70k, I was getting similar mileage. I cleaned the MAF, throttlebody, and replaced the sparkplugs. It now gets 26-28mpg. Always reset your average when you fill your tank so you can monitor it properly.

I did just do new plugs and cleaned the maf where is the throttlebody and whats the best way to clean it?

**Fivefingerdeathpunch** · 03-10-2011

this is a throttle body

See those pictures. that the throttle body, even tho these pic off the 97-03 car, you get the idea.

It at the end of the air duction for the intake from the air box. take it off and spray it will brake clean and wipe it off.

**wilder9032** · 03-11-2011

Fivefingerdeathpunch thank you so much this will help out a lot! so just spray all inside of it?

**Fivefingerdeathpunch** · 03-11-2011

yeah, remove the throttle body and spray the crap out of the inside and wipe it down good and make it all shiney and clean. Then put it back on.

**codyAK** · 03-11-2011

Originally Posted by copperpacecar

plus did you clock your mileage using the tach and the amount of fuel put in or did you use the mpg on the instrument cluster as that thing can be terribly inaccurate...use miles divided by gallons and see if its the same

Odo.

**footballplaya3k** · 03-12-2011

Personally I wouldn't use anything but MAF cleaner but that's just me. I'm getting 14mpg city right now if it makes you feel better.

**Phantom** · 03-14-2011

If you are getting less than 18mpg on a tank or two you have a problem, I was only able to get down to 18mpg two different times one was me trying to get a bad tank by driving like an ass all the time. The other tank was me running in SD mode doing some tuning.

What I would look for/do is:
Clean the MAF and TB (remove all sensors first)
Check for vacuum leaks
Replace the fuel filter
Replace the O2 sensor
Replace plugs and wires if they are old

BTW my car is NA so if you are supercharged I would figure the lowest mpg to get would be 16mpg.