Dtc p0171!

[Evo3742]

Hello All,
I recently got this code after I installed a brand new k&n panel filter. I did dab it with paper towels before install. I figured it was a dirty MAF. I cleaned it very throughly and still got this code. I probed the back of the plug of the MAF and had very good fluctuations. I thought it might be my O2 sensors, so I swapped the front and rear to see if I could get different readings but it turned out the same.
The runner ran fine before this code, yes I did try to run it with the old filter in but to no avail. It idles erraticly from 570 to 770, but drives fine.

Here are my readings at idle and at 2100 RPM

(Idle/2100RPM)
Load_PCT (%) 18.0-20.0/ 11.0
ETC 186 degrees/ 186
SHRTFT (%) 19.5/ 19.5
LONGFT (%) 19.5/ 19.5
RPM. 570-770/ 2100
SPARKADV 13.0 degrees/ 29.0
IAT. 89 degrees/ 91
MAF (lb/s). 0.01/ 0.02
TP (%) 8.6/ 11.0
O2B1S1 (V) 0.000- 0.005/ 0.055
SHRTFTB1S1 (%) 19.5/ 19.5
O2B1S2 (V) 0.000/ 0.030

If I left out any info that might help resolve this issue let me know and I will do my best to get it. Thank you.

E.Vo

 

[pauldub]

The code is only for bank 1. Maybe you have a bad or partially clogged injector on that bank.

 

[etc.]

It could possibly be a vacuum leak. I had the same code when one of the hoses to my to my catch can had a very minor leak. I initially thought it was O2 or MAF sensor related also.

 

[Evo3742]

Thanks for the replies, I've ran a bottle of GumOut One and done because I too thought it might be one of the injectors. And I listen to all the injectors with a stethoscope and they sound like they are working properly.
Everything vaccum wise seems to be where they belong and no leaks. Not sure guys.

Does anyone know if these readings I got are normal?

 

[Magmotor]

Does anyone know if these readings I got are normal?

Your O2B1 is way off. B1 is supposed to alternate between less than.35V to more than .55V continuously when engine is warm and at idle. Check your wiring harness from ECM to the sensor. If all is good replace the sensor.

 

[Evo3742]

Thank you, I have ordered some Denso (234-4162/234-4154) front and rear O2 sensors. When they arrive I will install and report back.

E.Vo

 

[Evo3742]

Sensors arrived and installed. I am still getting the same readings.

Your O2B1 is way off. B1 is supposed to alternate between less than.35V to more than .55V continuously when engine is warm and at idle. Check your wiring harness from ECM to the sensor. If all is good replace the sensor.

The voltage is not fluctuating between these tolerances. It will rise and then gradually fall back to the same voltage after I have given it throttle. Everything on the harness is good.

I guess I got some back-up sensors.

E.Vo

 

[LittleCaesar]

Did you unplug anything during the installation of the filter?

If there isn't a CEL, then I would guess there is a vacuum leak somewhere.

 

[Magmotor]

Sensors arrived and installed. I am still getting the same readings.



The voltage is not fluctuating between these tolerances. It will rise and then gradually fall back to the same voltage after I have given it throttle. Everything on the harness is good.

I guess I got some back-up sensors.

E.Vo

it's not your sensors..that voltage should remain constant, even at idle....well sh....tttt....hopen that would've got it but.....here is the pdf file for a PO171 from the 2000..should be the same....it has 9 flippen systems that have to be working right or it will throw the code..!! you said this happened right after you cleaned the MAF...a wet K&N filter will kill a maf every time....I guess go thru the 9 and check em...the last is the killer...the ECM might not be putting out the required voltage needed for the sensors....luck..!!

 

[Evo3742]

Fixed!!!!!

It could possibly be a vacuum leak. I had the same code when one of the hoses to my to my catch can had a very minor leak. I initially thought it was O2 or MAF sensor related also.

If there isn't a CEL, then I would guess there is a vacuum leak somewhere

You both were right. It was a vacuum leak. I had checked earlier in the week all the vacuum lines and did not find any sign of damage.

Today after installing new O2 sensors and checking voltage, I decided to do a carb cleaner leak detector. I went around the engine bay with a can and just started letting my intake have it. With engine running I went over all lines and tubing and got no idle response. So last thing to check was intake manifold and grey s'charger. Manifold checked and cleared ...then... I sprayed the boost port elbow on the sc and BAM! Idle jump. So I sprayed it again and again and again till tears of joy filled my eyes. It was where the elbow of the port meets the top of the blower, its gasket was gone, you could feel the vacuum with your hand. I grabbed a tube of Gasket maker and I sealed it up. After it cured so did my problem. O2s are fluctuating as they should and idle is like kitty, purring.

I couldn't believe I over looked it, then again I was thinking it was lines or tubes.

Thanks to all who chimed in with advice, couldn't have done it without this support.

Eric