Pontiac Repair: 06 pontiac, chevron techron, mass air flow sensor

Question
I have 105000 miles on my 06 grand prix.Ihad it tuned up at 103000 miles.It runs like a top. there are no check engine lights on. My gas mileage has gone from 27.5 to 23 mpg.A month ago.Any ideas?

Answer
Hi Norman:

well with out seeing it it's going to be purely a guess. with no check engine light one that makes matters worse as well. it may not be running up to part but not bad enough to make the service engine soon lmap to come on. At 100,000 you due for some basic tune up parts. Spark plugs Only AC Delco and a Pcv valve same thing only Delco. You may want to run  a couple of cans of Chevron techron fuel suystem cleaner though with a couple of full tanks of gas. A new air filter will not hurt to replace that and they are cheap enough. A few thother things to do get a can of Mass Air flow sensor cleaner and clean the MAF. a company called CRC makes the stuff I'm talking about it's in a red and white spray can. When you have the snorkel off clean the throttle body and throttle plat just a maintence It's not going to effect gas mialge but you sould do it nayways. Carb cleaner works great for that. Latly you may want to invest in 2 new heated oxygen sensors. as the engine get miles on it the sensors get coated with "junk" from the by products of combustion and there is no way to clean them they get degrated and don't work as effieciently as they did when the were new. They are a bit costly but they can "help" they fine tune the fuel mixture for the engine computer. Same thing with the sensors ONLY use AC DELCO parts. hope that helps you out. Good luck :-}

Oh one last thing ONLY use 87 octane fuel. the higher the octane the lower the fuel milage will be. There are more BTU's in a gallong of 87 octane fuel then in 89 or 93 octane. depending on where you live you may be starting to see e10 gasoline meaning that 10% of evey gallong of fuel has ethnol blended in the fuel. Where I live in NY ever gas pump is marked that way and the ethnol blended fuel will get you less fuel milage as well. GM cars that are not Flex Fuel engines are designed to run on up to 10% alcohol mixture with out an issue other then decreased fuel mialge.