Stupid ?. How many miles are on your car?..... Maybe change your spark plugs, or if your car has very high mileage a new O2 sensor may be in order. Also you should practice giving yourself like a 1/4 tank of gas left before you fill up. Letting it run all the way down puts more stress on the fuel pump, and all the crud that's on the bottom will get sucked up into the system plugging up you fuel filter or other components..... Can also try putting some Chevron Techron fuel injector cleaner in your next tank. Helps out on a car with some miles on it.

 

Well I don't know what the heck is going on with my tC, but I just had a personal record of 392 miles on the last tank. This is without making any changes to the previous configuration. Without cleaning or adjusting anything. The last 4 or 5 tanks immediately before this one were all below 300 and I was getting very alarmed. I don't know how to explain today's tank, but it looks like things are back to normal. I know it wasn't just 5 tanks of "bad gas" because they all came from different places. That means going from about 25mpg back up to 32mpg for absolutely no reason. It's a mystery, but I feel much better now.

 

I've noticed that my mileage has gone down a bit but I've had my tires on for a good 4 months now so it can't be that for me. Took my car in not too long ago for maintance but I noticed not so good gas mileage before that. I was thinking, could they (gas companies?) screwing around with our gas in California? Trying to get "cleaner" gas than what we already run?

Only reason I say this is because I know of other xD owners in other cities with traffic similiar to what I experience yet they get better mileage. Yes it also hinges on how you drive, but we've agreed we're fairly close in how we drive our cars.

 

hey rodC- did you ever check the maf sensor just to see if it was dirty? i know i'm dying of the suspense to know but yeah i'm glad it went back up. but ChelsDS from california is claiming odd fuel economy. I wouldn't doubt if they're screwing around with your gas out there! They've done it before!

did you get the gas from a different gas station or the same station different pump? I've seen wild fluctuations in mpg's from different pumps at the same station!

 

I've been getting my gas from different stations, but always either a Mobil or Shell station. I haven't checked the MAF sensor yet, as I am waiting for the cleaner kits to arrive first.

I'm on another good tank now. The current tank is on track to be 380-ish when it's finally done, so it looks like everything is back to normal. Maybe they really were screwing around with California's gas.

 

can I ask you are you an auto trans or 5-speed? I pretty much always use my cruse control and I dont really ever use the a/c and my mileage just sucks... tires are only about 5 months old there nitto neogen. i didnt notice any change when I cahnged my tires it stayed about the same. As for my filter I changed that like 6-7 months and sparks plugs were changes like 3 months ago. Is there anything else I could try and do to get some better mileage.

 

That's funny, I use my A/C constantly, I never use cruise-control, and I often drive with a heavy foot at the times when I'm not cruising steady on the freeway. My mileage has always been very high regardless of driving style.

The car is an auto, for the record. I have always geared my mods towards getting better mileage. I am lowered (better aerodynamics), and I installed a cold-air intake about a year ago (better fuel economy when the engine is not under heavy load). I installed a grounding kit which results in smoother and lower idling, saving gas. I have also performed as much weight-reduction as I can get away with. Most people are skeptical about some, or even all of these mods. Most people will tell you that intakes and grounding kits don't do cráp for mileage, but you cannot argue with the numbers. Aside from the oddities of the last couple of weeks, I have consistently scored 360 to 390 miles on every tank of gas since I bought the car and performed the upgrades 18 months ago.

 

So I did a bit of maintenance over the weekend. I washed and re-oiled the air filter, and I thoroughly cleaned the MAF sensor. I will report if I see any noticable increase or decrease in fuel economy and/or performance.

 

thanks for keeping us updated RodC

was that amber colored bulb on the outside of the maf sensor dirty?

 

Not using your a/c will help contribute to bad gas milage. Having your windows down all the time creates more drag on the vehicle which intells worst gas milage.

 

Hmmm, I don't recall seeing any amber colored bulb... ?

 

it's an amber colored bulb just on the outside of the tube where the maf sensor wires are. just wondering what condition it was in.. no problem if you don't remember.

 

Is that the bulb you are talking about? I didn't note what color mine was or what condition it was in, but I definitely cleaned it thoroughly from all angles with the MAF sensor cleaner.

I can't make any statements about gains or losses yet since I was mid-tank when I did the maintenance, but I just started a fresh tank tonight. I can at least say that there have been no major problems, so that means I didn't damage the MAF sensor. I have heard of some people breaking the sensors during overly vigorous cleaning. I have also heard of MAF sensors being fouled due to excess filter oil being sucked up the pipe. I seem to have avoided both of these scenarios.

 

thanks rodC, yeah that was the bulb, I should've searched for an image. thanks for the image. that's the idle air temperature sensor. the maf sensor wires are down inside that tube, they look like dental floss.

and yeah just cleaning it really doesn't damage it, unless you drop it while cleaning it ;) and yes, spraying it really hard up close could break the maf sensor wires, you're right!

and yes some aftermarket filters that need to be oiled, sometimes the oil can foul the maf sensor as well.

but sounds like everything is clean and fine now, so now we just get to wait and see what the fuel economy is