Originally Posted by shock41
Been reading on here about loss of fuel mileage, seems like the first question is always, have you changed fuel filter? Seems to me like if fuel filter was bad, it would suffer from lack of fuel and run bad. If it runs good not starving then how does a new filter help? Just trying to get my head around this. I ask because like so many others I have seen my mileage drop from about 18 down to about 12. I have a 01 with superchips, afe intake, 4" exhaust and 220,000 miles. I just did a tranny but the mileage drop was before that and did not improve after. I have been blaming it on the low sulpher fuel but after reading on here starting to wonder. I checked for codes and not showing any. I do drive it like I stole it , but I always have, so not sure why it would change so drastically. One thing I have noticed is at low rpm acceleration I get a good bit of black smoke. Like if i get on it a little hard at a light or if I get into it alittle hard at 50 in overdrive, don't remember it having this much smoke before. Clears up as soon as the rpms come up alittle. Turbo boost is still showing about 21 on hard acceleration running empty and higher under aload so think turbo is ok. So I guess after reading all that I have I am going to check ebpv for soot build up and change fuel filter. Still can't get my head around how the fuel filter would decrease mileage, seems if it were dirty it would allow less fuel to flow and decrease it, but since I have'nt changed it in over 100,000 miles I think its probably due. I'll post back as to what happens.
For one, when it comes down to any kind of filter for any kind of engine, it's all about flow. Over time, your fuel filter accumulates all sorts of foreign debris in it's media. When the fuel filter(or ANY filter)isn't changed on regular basis, the debris will cause a restriction in flowing the fuel, causing you to get crappy mileage. Another thing that'll cause poor fuel mileage is when you "drive it like you stole it". Just like any engine, it's gonna get crappy mpg if your constantly standing on it. I'm not saying to drive like an old lady on her way home to watch Matlock, but tone down the speed & you'll notice a slight difference. Your smoke: it's probably from the SuperChips. It's doing it's job. It's just increasing your fuel intake to the injectors. The black smoke @ low RPM is just unburnt fuel. And for your turbo; you really don't wanna "guess" if your turbo's ok. If you're really concerned, take your intake arm off & look @ the condition of your compressor wheel. If you want to anal retentively check your turbo, pull it off & check your bearing, oilers, turbine, etc. My advice to you: if you want to keep your truck in "drive it like you stole it" condition, give it a little more love. Change all of your fitlers regularly. It's sounds like you're beating the snot out of it.