MY CHECK ENGINE LIGHT KEEPS COMING ON AND WHEN I READ THE CODES I COME UP WITH P0170 AND P0173 WHICH TRANSLATES TO FUEL TRIM MALFUNCTION BANK 1, AND FUEL TRIM MALFUNCTION BANK 2, RESPECTIVELY. WHAT THE @#$% IS FUEL TRIM MALFUNCTION ANYWAY? THE CAR SEEMS TO BE RUNNING JUST FINE, NO LOSS OF PERFORMANCE OR MILEAGE. AFTER I CLEAR THE CODES, THE NEXT I DRIVE THE CAR IT WILL COME BACK IN ABOUT TWENTY MINUTES. ANY IDEA WHAT COULD BE CAUSING THIS? ANY HELP IS GREATLY APRECIATED!![8D]

 

Typically it's a dirty MAF's that's the culprit. Yank it out, get some MAF cleaner at your local auto supply shop and spray the heck out of the gold colored wire at the very tip of the MAF insert. Do not touch this wire as you will contaminate it, just spray it hard to get the schmutz off. Wear latex gloves so you don't get this chemical all over your hands andsafety glassesas the spray goes everywhere.

So what is a fuel trim error you ask. You have a bunch of O2 sensors that determine if you are running rich or lean. You have an ECU that interperts this information and sets the pulse width, or in english, the amount of time to open the fuel injectors, longer the pulse, more fuel enters the combustion chamber. There comes a point where the pulse width exceeds a certain amount where adding more fuel (or triming)is futile and you get a fuel trim error. So how can this happen. The most obvious is you have a vacuum leak, too much air is entering the engine and the ECU can't trim fuel enough to make up for it. If you had a vaccum leak, you would know it, the car would run like poo. So the less obvious is the MAF. It gets dirty, why, because you are not changing your air filter enough is one though or using junk aftermarket filters like K&N. Air passes by the wire in the MAF, it's coatedwith schmutz and gets incorrect readings. The ECU says the MAF tells me I don't have enough air flow so it leans out the mixture, yet on the otherhand the O2 sensors says it's too lean and throws a fuel trim error. Hope this helps you understand why you need to make that $6 investment in a can of MAF cleaner.