P0171 - System Lean Bank #1 - MERGED

[ReZPunK]

yup, keeps coming back.

checked streaming data - all seemed ok.

cleaned MAF - clean

checked for vacuum leaks - still possible

checked date of replacement fuel filter - ok.

any thoughts?

im thinking of going through and replacing all vacuum lines some are getting alittle brittle.

 

[ReZPunK]

oh i just thought of something. i know that the vacuum line from the inlet hose to the boost module is restricted...i replaced it because it was brittle and broke, i used a single lenght of tubing without the thinner piece, would this be causing a lean situation?

 

[Shorty]

I think that will cause you to have less boosting ability. Let me look that one up...

 

[Shorty]

Possible exhaust leakage? Oher than that maybe a coolant temp sensor.

I'd be will to bet that boost buggy has an up-pipe leak.

 

[Trevor723]

oh i just thought of something. i know that the vacuum line from the inlet hose to the boost module is restricted...i replaced it because it was brittle and broke, i used a single lenght of tubing without the thinner piece, would this be causing a lean situation?

I dont think that one is restricted in the way the one from the compressor is... it's just reduced from the turbo inlet to the boost solenoid.. and I think that's only in order to have a beefier nipple on the turbo inlet.

 

[ReZPunK]

another thing i was thinking is that the code came after i installed the perrin inlet hose. along with the intake i installed a few months ago, would change the amount of air flowing by the MAF. that could also cause teh lean code as well..

i will look into the up pipe leak (good chance to install the godspeed uppipe and new gaskets)

 

[Trevor723]

If the intake has some funny bends right before or after the maf or is a different diameter than the stock maf housing you will definetly be fooling the ecu.

 

[ReZPunK]

yeah im thinking that's the cause. the setup is bigger in diameter for sure, just the intake by itself didnt throw the light..but as soon as i installed the Perrin inlet hose, it setoff the next day.

would a reflash/tune work in correcting this?

paging antonio!

 

[ralli]

Sounds like we need to run some data logging with the MAF tool and see if it wants to change your MAF settings. If the pipe around where your MAF is a larger diameter then that will give you a lean setup.

We can turn off the CEL, but I'd rather try to fix it if possible.

 

[Evil Jeff]

So, on my way back from hell today, I stopped and had a friend scan the CEL I'm getting. Came back as "Fuel too lean, bank 1". Basically what the car is doing is running like ass from 3-4.5K, especially when I get stabby with my right foot. Consensus seems to be O2 sensor. Ideas?

 

[ralli]

What mods do you have done? Intake or anything?

It could possibly be O2 sensor also.

 

[Evil Jeff]

Nothing drastic. A GP Moto silencer delete pipe and an STi TBE is it. Oh, and it came with a K&N air filter.

 

[Jimbo]

Bank 1? What in the engine comes in banks? If you were pushing too much air through for the fuel injectors to keep up with, would that end up in a lean situation?

 

[inski]

p0171

system

 

[ReZPunK]

dirty maf. brake kleen it and reset cel. if it comes back dig deeper. start small and work your way to bigger stuff.

often the oils from the K&N will end up on the MAF sensor and it wil read all silly. i do mine like once a month just because a clean maf is a happy maf.

 

[inski]

Ah, good point, wise old RezRob. 8)

 

[akinaspeedstar]

wait can you actually use brake clean on a maf with out ruining it???

my car has a K&n and in the past 8 months is isn't really running as smoothly as it once was.

so if i spray the maf with brake clean that's not going to kill it? hmm... i was thinking electronic cleaner at best. since i have a hot mesh on car. would carb cleaner work too?

 

[Jimbo]

Can't remember what compound you should/should not use, but there's something that should NOT be used. I'd search myself now, but have to go shop for TVs (oh, bother ;D)

 

[inski]

Your 99 has the 'hot-film' MAF used only on the 1999 MY, dont touch it, it will exploded and mess up your DNA and your childrens' DNA and your roomates DNA. 99 was a bad year for Scooby MAFs.

They make MAF cleaner, sold at parts stores, less harsh than brake cleaner. I wouldn't recommend it on the 99s.

It(brake clean) worked on my 97, my Mustang, and air meter Escort GT, and Rez's car and my Golf (for a week or two when it bought the big one and had to locate a new one). Not sure it will work for everyone, but might be worth a shot on Jeff's car if he doesn't want visit the shop. Might fudge everything up too. If it looks gooey dirty inside, I'd try it.