I got P0171...System too lean

This is my data log... yesterday my trims would stay at -0.94 and 0.91
LTFT Idle and Cruise
now trims are 9.17 and 12.5

https://www.dropbox.com/s/qtl6qxe0ip...4_10.53.48.csv

 

Vacuum leak or exhaust leak. Check your lines, usually the line from you fuel pressure regulator to the intake manifold. It's by your oil dipstick.

 

If it keeps popping up it probably is the sensor. I changed my sensor out a couple years ago. Easy with an aftermarket o2 housing

Sorry, thought it was 1-9 forum

 

I will look for leaks... its weird.. today was a little cold.. like 55F outside.. and my AFR stayed fine.. sometimes would go to 13.. while crusing but then ocilate between 14 15 like noormal...

When its 90-80 outside is when i start running rich... :/? maybe its just the tune??

 

I checked all vacum lines... intake.. everything is tight. no leaks...
One thing that i notice is... while cruising im not hitting boost and I let go of the gas and my synapse dv makes th pshh noise... before it would not do it... only if i was boosting...

Could my synapse be leaking? should I tighten the nut on top of it?

 

Yes...could be

 

how do i fix bov leak? just tighten it?

 

If you're talking about the nut I am thinking, do not touch it. The nut on the top is what adjusts when the BOV opens up (tighten if you want it to open at higher psi, loosen if you want it to open at lower psi).

How did you check your vacuum leaks? Did you do a boost leak test? You can always grab a can of starter fluid and spray some of the vacuum hose connections with the car running. If the idle raises up noticeably that means you found a vacuum leak, or just do the boost leak test with a spray bottle of soapy water.

 

I am not sure how you adjust that one. Search the forums, youtube, google, or call the manufacture for directions.

I also was having similar issues with my Evo. My fuel trims would fluctuate drastically. I could start at close to 0.0, and then after a 10 mile trip, my trims would be maxed at 12.5's.

That tuner thought perhaps it was from my bov (turbosmart dualport running 50/50). So I put back on the stock DV and the problems persisted. I did not throw a p0171 code, but I did throw a p0172 code (to rich).

In the end, and after numerous mechanical tests and headaches, the issue turned out to be a bad tune.

 

I'm not sure what exhaust manifold you have but also check to see if it's cracked. it could also cause your condition.

 

I sprayed soapy water.. no leaks.. baby powder.. no leaks.. took my intake off and put it back in there.. tight...

I have the stock manifold.. dont see cracks or hear any air leaking.

It is either the tune, maf sensor or bov
O2 sensor is not the cause of this.

Im gonna log MAF voltage... does anybody knows what is normal voltage?

 

if your MAF is dead, it will just read "0" volts when its running

my guess is a bad tune
warmer weather, etc. You're running lean, that's why your trims are so high as well.

Contact tuner

 

yea my maf is good.. yea i think is the tune.. i was reading about someone having the same issue and had to mess with the MAP vs MAT table. I took my car back to the tuning shop like a month ago because when my AC was on... the idle sucked. I read the tune and saw that the tuner changed some values in the MAP vs MAT tables... Maybe I should flash it back to the first tune...

just flashed it to the old tune... ill see what happens

 

if you're running a cone air filter with no heat shield, it will idle weird when the AC in one because the fan blows hot air onto it. It's not a tune related issue tho...just need a heat shield.

 

But that wouldn't explain his p0171 code right?