I cleaned the intake and throttle body a few weeks ago and I've got through three tanks since then. Before I did this I was getting about 17.5/gallon and now I'm getting just over 15. Same driving conditions and no extra weight in the car. From the other posts I've read it seems that most people get better mileage. Anyone else experience a drop like this?

 

If you cleaned the TB while it was on the engine, there isn't anywhere for most of the gunk to go except down into the intake and the IAC valve under the TB. It could have actually made things worse. If you didn't take the TB off the 1st time, then I would remove it, separate it from the IAC valve, clean both of those and then clean the intake again. You can re-use the TB and IAC gaskets, but new ones are <$5 ea. from the dealer so I recommend getting those too. Then pull the negative battery cable off for about 45 minutes to reset the ECM so it can re-map the new air/fuel mixture when it's all clean. You may want to clean the MAF (it's right after the airbox) with some spray MAF cleaner while your at it also.

 

Hey Brian. I did clean it while on the engine and it was FILTHY! I wondered about all that crap running down into the engine. I'll give that a shot. I did clean the MAF at about the same time. I'll tackle that tomorrow. Thanks for the tips!

 

My mileage fell off a cliff and I change my plugs that had 30k+ on them....back to regular mpg

 

I did my plugs about three months ago and got a gain of 2-3 mpg. Now I'm even worse than I was prior to that....