2001 SE Fuel Mileage Drop

[fixit1070]

Does anyone know what would cause a drop in fuel mileage.I had the spark plugs changed and the normal tune up items done ( fuel filter,air filter,pcv valve,oil) but the fuel mileage is still lower that it used to be.I used to get around 510 miles per tank now I'm lucky to get 460 or sometimes less.I drive mostly highway miles and I am very puzzled by the drop in mileage.I even changed to synthetic oil.


Any help would be appriciated.

[rodeo02]

Wow! If you were getting 520 miles out of tank, that's ~25mpg. That is phenomenally good for an Essex 3.8L. 460 is not a huge drop. I'd look at your tire pressures. I thought my average of ~23mpg was good!

Joel

[LeSabre97mint]

Fixit

How many miles are there on your 2000? How long have you owned it? Have you noticed anything different when it's running.

Regards

Dan

[fixit1070]

The van has approx 108,500 miles.I have had it since late 2003 .The only thing that is different when it is running is that every so often it will start to sputter like it is going to stall and sometimes does and other times it corrects it self and returns to normal idle.The van has over all been good but it seems to be getting poor mileage.I had the spark plugs changed at around 75,000 miles and thats when the mileage slowly started to change.At the time of the new plugs (autolite double platinum)75k miles I also had new plug wires and the usual tune up items done.I had the plugs changed this past weekend and still no impovement in mileage.I purchased Autolite Platinum plugs this time.The van had the trans fluid changed at 95k miles and the coolant changed at that time also.

I borrowed a scanner and there are no codes in the computer.

I was hoping it was something I was missing that would help improve the fuel economy.




Thanks

[phil-l]

The idle problem you're seeing is likely the IAC (Idle Air Control) valve.

It's easy to replace - or it responds well to cleaning.

[fixit1070]

Where do I find the Idle Air Control Valve ?

[phil-l]

It's attached to the top of the throttle body.

Quick hint: Have an assistant get in the van (while the engine is turned off) and repeatedly press and release the gas pedal while you watch under the hood. You'll see some hardware that moves with the gas pedal. That's the throttle body!

The IAC is on top of the throttle body, and is attached with two bolts. It also has a two-wire electrical connector on it. You'll find many references to the IAC; search through the forums!