My 95 2.5L Contour with 104,000 miles has been kind of running sluggish recently. I looked at the air filter and it was fine. I then disconnected the air filter from the throttle body and notice that the back side of the butterfly valve was all gunked up. I sprayed some carb. cleaner and cleaned up as far as I could reach with my finger and some paper towel. It's running a lot better now but I'm sure there's more that can be cleaned.
Some questions: How does this stuff form and is there anything I can do to prevent it in the future? Is it the type of gas I use (usually 87 octane SpeedWay gas)? Every oil change I do pour in some STP FI cleaner into the gas tank. What's the best way to clean this? Any pointers to website with instructions would be great.
Most of the carbon comes from the EGR which actually routes exhaust gases in just behind the throttle body. (where you opened the butterfly and saw all the black stuff) To clean it really well, remove the TB and clean with TB cleaner and soft rags and toothpicks for the big chunks. Wipe or vacuum all the junk out before reassembling and starting the car.
