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SUV poor gas Milage


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Bought a used 2014 GMC Acadia with 96,000 miles at the end of July. I’ve changed out the Transmission Fluid, differential fluid, coolant, air filter, cabin filter and oil as soon as I bought it. Getting About 10 miles to the gallon.

had a mechanic replace the spark plugs, (removing the intake intimidated me) but he did a horrible job putting intake back on (found 2 hoses still detached and had to re attach the tube going from MAF to the throttle body cause it was seated wrong, so much for that…)

Cleaned the throttle body, cleaned the MAF sensor. No odd smoke coming out of exhaust. But I’m still getting 9-10 MPG driving around town. There are No codes on a 4 system check. It drives fine. Shifts fine. Idle seems fine. But long term fuel trim is at about -18%. Any ideas what I should try next? 

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2 Answers

You probably have a partially clogged, leaking injector.


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