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Ok I have a 99 v6 I started a tune up on since I was getting 16-17 mpg
I have changed the plugs Air filter Oil & filter Checked the belts
While doing this I saw a lot of build up on the plug tips and that my tail pipe had a lot of carbon build up so I changed out the spark plugs in the hopes of bettering the mpg
But at my last fill up my idle is shaky and the mpg was 14.7
I do not horse my car and my driving style has not changed the only thing that is different is I used shell gas instead of Exxon like I normally do or just got bad gas not sure
So now that I have told you guys all that Is there something I missed in my tune up? Or A way to fix this running rich I know a number of v6 mustangs out there get around 23mpg and I would like to get my car at that level
Any help with this would be great
Oh and the car is totally stock as far as I can tell I have not done anything to it an donít really plane to Might put duel exhaust and an intake one it one day
CKL In life there is no black and white, only shades of gray!
You and I are in the same boat. I've been getting in the 15's for a while, and started replacing things. Try replacing your fuel filter, check your tire pressure, (I know, it's a no brainer, but you never know) Maybe give your inside a good old cleaning with some seafoam. Check your PCV valve, it may need cleaning.
Dual exhaust w/Flowmaster super 44's.
GoodYear F1 tires
17" five spoke GT rims
Painted calipers, Painted pony, flat black painted hood stripe, flat black painted spoiler.
If the idle's rough, think back to your work first. Did you gap the spark plugs correctly? Are all the fuel lines tightly attached to the fuel filter? Did you tighten drain plug enough? Is the oil filter tight? Oil Filler cap on? Air Filter placed correctly?
If all of the above is yes, move onto the fuel pump. That's the main cause of stumbling for our cars.
so you think it is the EGR?.. cost only about $50.
i just replaced PCV valve since old was alittle clogged.
my spark plugs looked pretty clean.
i was told by a mechanic it would not be a fuel pump, a fuel pump wouldnt give signs, it would just give out.
fuel filter could be another thing i shall replace. anyother comments i am glad to hear. thanks mike.
everybody experiencing bad millage problems which i gave 12.6 MPG.. before you replace anything expensive try Fuel injecter cleaner. and spray throttle body cleaner in the Throttle body(open up the butterfly) and also try EGR valve ifnot needing to be replaced.
these seemed to help my problem from results i see right now.