p0171 code

[shitstang01]

First off heads up I’m a noob
Car has a rattling raspy noise coming from the passenger side, was told it’s a header leak by a shop and two of the bolts have came out but they told me not to worry about it as it wouldn’t affect performance
Clearly that’s not true, cars been running very differently and gas noticeably sucks. Sent some datalogs to my tuner and they said it’s running VERY lean and to get it fixed ASAP without going in to much detail. This is my daily driver and gonna need to wing it for a few days.. will it be safe to drive for a few more days ? Would some higher octane gas help in the meantime or should I just not drive it at all, at the same time don’t wanna blow my engine. Thanks

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[K4fxd]

There is no way to answer that without seeing the data log.

I'd say if your tuner is concerned I'd not drive it any more than I needed to.

 

[shitstang01]

There is no way to answer that without seeing the data log.

I'd say if your tuner is concerned I'd not drive it any more than I needed to.

Here’s a glimpse might be useful.

 

[K4fxd]

I'm not an expert by any means.

There is not enough data for a real answer, not long enough and RPM never got above 1K

 

[shitstang01]

I'm not an expert by any means.

There is not enough data for a real answer, not long enough and RPM never got above 1K

 

[K4fxd]

I don't know whose format that is but it is hard to read.

You do have one bank with problems, very lean. The short terms are keeping up with it, at least to 2000 RPM.


I would take your tuners advise and get it fixed ASAP

I wouldn't drive it any more than necessary and I for sure would not hot rod it.

 

[shitstang01]

I don't know whose format that is but it is hard to read.

You do have one bank with problems, very lean. The short terms are keeping up with it, at least to 2000 RPM.


I would take your tuners advise and get it fixed ASAP

I wouldn't drive it any more than necessary and I for sure would not hot rod it.

I had to export it to a pdf file to upload it so it came out a bit different. So the short terms try and compensate? Thanks

 

[K4fxd]

The problem with exhaust leaks is we don't know if the O2 sensor is getting a true reading or not. The sensor could be reading exhaust plus outside air. That will cause the ECM to add fuel to the point of washing down the cylinders.

I'd like to see injector duty cycle on that log.

Fix it.

 

[slime_bullet]

I dont see any lean conditions, ltft and stft are well within tolerance and within 2% of each other. afr looks good too

 

[Adamone92]

I dont see any lean conditions, ltft and stft are well within tolerance and within 2% of each other. afr looks good too

bank one being at 1.656 while bank two is at or under 1 doesn't look lean to you?

if you were told you have an exhaust leak at the header i would get that fixed and see if that changes things and then go from there...

if that air isnt making it to the 02 sensors then they could be seeing it as running rich, and thus try to add more air (less fuel) to compensate, making it lean. It looks like its doing that about as much as the 02 sensors can control on their own. after a certain point it cant do much more..

at least thats my understanding of STFT. The LTFT on bank 1 is showing a decent bit lean at ~1.2..thus making that the new baseline and your STFT bank 1 is still going lean. im sure there is someone that knows much more about this though and can correct me if im wrong.

 

[slime_bullet]

bank one being at 1.656 while bank two is at or under 1 doesn't look lean to you?

if you were told you have an exhaust leak at the header i would get that fixed and see if that changes things and then go from there...

if that air isnt making it to the 02 sensors then they could be seeing it as running rich, and thus try to add more air (less fuel) to compensate, making it lean. It looks like its doing that about as much as the 02 sensors can control on their own. after a certain point it cant do much more..

at least thats my understanding of STFT. The LTFT on bank 1 is showing a decent bit lean at ~1.2..thus making that the new baseline and your STFT bank 1 is still going lean. im sure there is someone that knows much more about this though and can correct me if im wrong.

Made an assumption that the fuel trims were represented as a percent in the file. If its a ratio then adding 60% more fuel is definite lean, and should throw a code

 

[K4fxd]

Yes, it is adding 60% more fuel on that bank. It looks lean on the log but the engine is most probably running pig rich.

Outside air is getting to the sensor making the ECM think the bank is lean, then adds fuel.

 

[Andrew@Lethal]

Make sure those header bolts are tight. It could be messing with your O2 readings.

 

[shitstang01]

Make sure those header bolts are tight. It could be messing with your O2 readings.

Yes that’s where the raspy sound seems to be coming from.

 

[Andrew@Lethal]

Yes that’s where the raspy sound seems to be coming from.

Yup, sounds like to shop might have got sloppy with the install. Bring it back and tell them to fix it. I would not be driving your car if it's making it run lean.

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