What could cause high boost reading/bad gas mileage

[jimbo058]

Monday morning while driving to work, I noticed my boost gauge was reading about 10-15 lbs of boost higher than normal. For example, when going up a slight hill, it usually reads minus-10 lbs on the gauge, and it was reading +5 lbs of boost.

The engine did not seem like it was laboring any harder than usual, but I burned about 2 times the usual amount of gas going to work and back. I was just driving along with traffic, not accelerating fast or anything. A 42-mile round trip, combination city-hwy.

The next day, it acted completely normal, with the boost gauge reading like it should and the gas mileage going back up to normal. Since then, I have reset the ECU and re-flashed.

Any ideas what would make it temporarily show way-higher boost and burn up twice the gas ? I eliminated things like parking brake engaged, foot on the brakes.

'09 WRX, Catback, Cobb Stage 1, no other power mods.

[pzr2874]

O2 sensor shittin the bed? You clean the MAF?

[jimbo058]

I religiously clean the MAF once a month. O2 sensor - that is a great idea. I saw one in the downpipe/midpipe area. Isn't there another one somewhere else ?

[jimbo058]

Found front O2 sensor on parts diagram !!! Answered my own question.

[psinuse]

Your over cleaning your MAF...

[turmic]

Keep your foot off the gas pedal.

[pzr2874]

Check your airbox.... mine keeps acting up. Just an idea.

[jimbo058]

Ok, I cleaned my air filter this weekend, and used air-filter sealing grease. I made sure the airbox was mounted correctly, with the two tabs inserted on the bottom, and two spring-hooks on the top. So far, so good. It ran great on the way to work this morning (Monday again already ... argggghhh !!)