>> LEAN both banks, P0171 & P0174, FTrims WAY positive, O2 sensors "bouncing" full range!...

[fixizin]

... yet it's running fine and idling normally... hmmm... vacuum leak?

DATASTREAM(idle): LTFT1&2 rock solid at 25.0%, STFTs bubbling in the high 30s, occasionally breaking 40% !! O2 sensors rapidly changing from 0.06V up to 0.88

Also fuel mileage seems to be suffering, down around 11MPG around town, but no Rich smell or hot cats... Err, umm, WHERE do I start?

(Recently cleaned MAF and swapped air filter--no change... however, WAY overdue for a Fuel Filter... )

 

[fixizin]

OK, unplugged the IAC at WARM IDLE, and ZERO change... HOW to check for vacuum leaks? Smoke from an incense stick would probably be useless with all the draft from the belt-driven fan... will first carefully check the "elephant trunk" intake tube... lotta connections and "joints" there...

 

[pentode]

Try the old brake clean/carb clean trick... Something aerosol and flammable (some brake cleaners aren't flammable anymore ) Spray around the intake until you hear the revs kick up.

 

[fixizin]

OK, here's a pic of the breather hose connector, at about the halfway point on the snorkel/intake tube, looking rather aged and CRACKED... guessing that's the IAT sensor next to it...?

Should probably use some tire-shine/Black Magic on Ye Olde "elephant trunk"...

 

[fixizin]

Try the old brake clean/carb clean trick... Something aerosol and flammable (some brake cleaners aren't flammable anymore ) Spray around the intake until you hear the revs kick up.

Sounds viable, since given the OBD #'s, it's a LOT of air bypassing the MAF... OTOH, if it turns out none my sprays are flammable, I could drop the serpentine belt and run it for just a few minutes for the smoke test...?

 

[danielschudel]

YouTube has a good many diy smoke test machine videos. I did one and found my evap system leak in five minutes. Not hard to build and not expensive.

 

[bills4065]

Increase your rpm to 3000 and check your long term fuel trims. If they have gotten a lot better at 3000 rpm - you are looking for a vacuum leak.