wooby99

My wife's 06 Evo just threw code Po171 on the way home from work. Did some research on it, but here is the baffling part. Normally the vacuum is 13-18 at idle, now it's 25 and when you give it a little gas it goes up to 30. She said it will still boost, but not sure if like before because with code she didn't want to hurt anything. This was noticed after ses light came on. This should eliminate some causes for this code. Need some input on this on were to look....wife doesn't want to drive her baby with this problem. Thanks

barneyb

The only way I know of to make the manifold vacuum increase is to plug the intake. Something is wrong there. It sould be easy to locate with a little inspecting.

06RedRalli

iTrader: (49)

That code is due to a lean condition in bank 1.

barneyb

Yeah, I know, engine starved for air and reading lean. Unless her boost gauge has gone completely wacko, I gotta think something has happend to the Mass Air Sensor causing it to give a bad reading - maybe the honeycomb or air filter has collapsed.

06RedRalli

iTrader: (49)

Possibly a bad o2 sensor.

barneyb

Remember, the OP said the vacuum is going to 30 with a little throttle (actually the vacuum can't go to 30, that's the vacuum of outer space - but gauges aren't all that accurate). So, anyway, whatever the actual reading is, it is abnormally high. I've read here of people with big turbos having sucked the honeycomb in.

wooby99

Thanks for the input. Had pulled the code with a scantool and got all the info printed out from alldata. Trying to narrow it down to make quickly fix the problem. My wife works days and me nights so I got about an hour each day to work on her Evo.