In changing the water pump on my 95 T/A I found the mass air-flow sensor black w/ crud as well as the intake plenum. I'm thinking that maybe my injectors are black too. Where does this stuff come from since I thought only clean air passes thru all this stuff. Is my performance suffering? I used carb cleaner in there as much as I could reach but is that enough? Car has 86000 mi. Thanks a lot! Larry

 

One more thing... I've been using BP gas most of the time and someone told me reciently that their gas isn't good for modern FI cars. Larry

 

The air filter and intake plumbing ahead of it would be responsible for keeping the MAF clean.

The internal intake manifold can often be a victim of some excess oily gasses coming in from the PCV fresh air hose on the side of the throttle body. It's not really that uncommon.

I find it ludicrous that anyone would suggest any major, modern gasoline company's gas is not good enough to run in any kind of vehicle.

 

Dirt in the MAF sensor could come from fine particles trapped by excessive oil carryover from a gauze-type air filter. Might also indicate the check valves on the AIR connections at the exhaust manifolds are faulty, and exhaust is finding its way back through the AIR pump and into the intake duct.

 

It seems pretty common for people to over oil a K&N style filter and then that stuff will get sucked down the intake. I've never seen oily residue on the inside of the intake tubing. I have seen oil residue on the MAF because of a heavyily oiled filter.