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More car troubles, p0171 code and sketchy starts


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So my car has a new problem. Got off work yesterday and went to start my car and it really struggled, it took 3 or 4 times to get it to turn over and idle. Once it started it had no problems running or idling at all. I got home and pulled the code and it came up p0171, system too lean. Any ideas? I was thinking maybe a vacuum leak but its strange that the engine only seems to struggle when starting up.

I've replaced the 02 sensor, the spark plugs, the coil packs, cleaned the MAF sensor, all within a couple months so i dont think its any of those...

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P0171 Fuel System Lean (Bank 1), if i'm not mistaken, that is the code that pulls up if you scanned with an accessport? I just recently started having that code pull up myself (but have not had the misfortune of the hard starts). I have called a few trusted Subaru friends of mine, and they have suggested cleaning my MAF (which you have noted you have already done). They also suggested that if I had played with my intake at all, to ensure that none of the lines were leaking or loose, as that may allow for unmetered air to pass by.
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im having the same problems. cold starts are fine, even after warm up idles fine, then I turn off the car when it warms up, turn it off then restart it, idle is rough and misfiring. cleaned maf, new spark plugs, checked for leaks, still no solution :(

 

Good luck man, I just found out it's my head gasket :eek: It's gonna be a doozy

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Good luck man, I just found out it's my head gasket :eek: It's gonna be a doozy

I was told it was a possible head gasket too. I am throwing a p0420 too which has to do with emissions I need to get in touch with the man who tuned my car to see if its because he didn't uncheck that because I have no cat. :spin: :mad:lego problems

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Doesn't this code pop up when the BPV recirculation hose is disconnected under the TMIC?

You should look there

I have a FMIC and the hose is good I think its because my tuner is not familiar with legacys but if he does WRX and STI he should be able to tune mine. if he cant fix it im going to have snail performance tune it, because im sick of cheap tunes. :mad:

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I had same problem, same code, back in August. Took long time to figure it out, but turned out it was the front O2 sensor. For whatever reason, it wouldn't regularly trip a code, and everything seemed fine, and just when the tuner was about to start pulling his hair out, the sensor failed completely.

 

So it was a headache, and it wasn't cheap, but it was resolved.

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I had same problem, same code, back in August. Took long time to figure it out, but turned out it was the front O2 sensor. For whatever reason, it wouldn't regularly trip a code, and everything seemed fine, and just when the tuner was about to start pulling his hair out, the sensor failed completely.

 

So it was a headache, and it wasn't cheap, but it was resolved.

 

That's funny cause I've actually had this code read out before and just googled it.

The first link was to a legacygt thread saying to change the front O2 sensor. Bought one online and changed it out in 5 minutes and boom, no more code :spin:

 

Unfortunately this time it wasn't so easy...

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So my car has a new problem. Got off work yesterday and went to start my car and it really struggled, it took 3 or 4 times to get it to turn over and idle. Once it started it had no problems running or idling at all. I got home and pulled the code and it came up p0171, system too lean. Any ideas? I was thinking maybe a vacuum leak but its strange that the engine only seems to struggle when starting up.

I've replaced the 02 sensor, the spark plugs, the coil packs, cleaned the MAF sensor, all within a couple months so i dont think its any of those...

 

System too lean can also be the MAP sensor that isn't working as it should. In some cases they get sticky and hesitant to move.

 

Do a data log if you can and make sure you log rpm, maf, map and throttle opening.

 

If the engine hesitates when flooring the throttle at lower rpms and the MAP sensor doesn't follow up in pressure change then you have caught the culprit.

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That's funny cause I've actually had this code read out before and just googled it.

The first link was to a legacygt thread saying to change the front O2 sensor. Bought one online and changed it out in 5 minutes and boom, no more code :spin:

 

Unfortunately this time it wasn't so easy...

 

Yeah...I wasn't exactly thrilled with the tuner/shop on this one, but there were certainly things that made it difficult to figure out.

 

First, I had just installed a new AVCS valve (I had replaced the drive side one last year, and just decided to put a new one in, no other reason.) Second, since my original tune, I had installed an SPT intake. And third, on the way to the shop for my appointment, the light goes back out. They data logged, looked around and they found a disconnected hose, just assumed that must be it, reconnected it and handed the car back to me. Light went back on a few days later, car went back to the shop. They were about to run it through some testing on the dyno when the O2 sensor failed completely, and it's my understanding it threw a code denoting this.

 

When they handed the car back the first time, they barely charged anything, which was cool. But when I got it the second time, it appeared they charged for the time spent the first time, so between time and a sensor, it wasn't cheap. And I was without my car for the better part of 2+ weeks.

 

The whole thing irked me mainly because I had researched this and handed them a "top 10" list of typical causes, with O2 sensor right there near the top, and it seems like they ignored it - as many shops/techs do - not liking "smart asses" who hand them info they got on the internet. Least that's my take on it, at times.

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