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Discussion Starter #1
My Buick is running a little funny, before so a intake valve inlet busted (may not be relevant). That's fixed, but I still get these error codes, for granted i cleaned the Mass Air Flow sensor, and this two codes still show up.
 

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Bank one and bank two are running lean. Could be O2 sensors or a myriad of other items.

Here's a link to some information about the codes:

http://repairpal.com/OBD-II-Code-P0171-and-P0174

My guess, with your description of the work done, is a leaking intake manifold gasket.
 

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Those are codes for both banks lean and the thing in common is the intake area and associated parts.

It's possible your purge valve is leaking. It's easy to remove the hose from it and see if there's any vacuum on the nipple with the engine running and the wire connector disconnected, try it without disconnecting the wire first(that can set a code). There shouldn't be any vacuum on it unless commanded on by the PCM. You can put your finger on it for a second a few times to test. You shouldn't feel anything there. The purge valve is located on the upper intake near the radiator/throttle body. that's a really common one.

The MAF sensor can also be a problem along with the air tube that goes from it to the throttle. I'm thinking your "intake valve inlet" is the Intake Air Tube which will also set those codes.

Look across the back of the intake for a vacuum hose nipple. There may be one with a cap leaking or missing. Check the crankcase vent hose(s)...left valve cover to intake air tube and right valve cover to upper intake manifold(left=front, right=rear).

Fuel with too high of an alcohol content, low fuel pressure or restricted injectors can also contribute.
 

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Discussion Starter #4
BadAV said:
Bank one and bank two are running lean. Could be O2 sensors or a myriad of other items.

Here's a link to some information about the codes:

http://repairpal.com/OBD-II-Code-P0171-and-P0174

My guess, with your description of the work done, is a leaking intake manifold gasket.
Thanks, I am going to change out the air filter, and clean the intake in hopes to fix the issue. If not then the gasket and sparkplugs are next!
 

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Discussion Starter #5
whipster said:
Those are codes for both banks lean and the thing in common is the intake area and associated parts.

It's possible your purge valve is leaking. It's easy to remove the hose from it and see if there's any vacuum on the nipple with the engine running and the wire connector disconnected, try it without disconnecting the wire first(that can set a code). There shouldn't be any vacuum on it unless commanded on by the PCM. You can put your finger on it for a second a few times to test. You shouldn't feel anything there. The purge valve is located on the upper intake near the radiator/throttle body. that's a really common one.

The MAF sensor can also be a problem along with the air tube that goes from it to the throttle. I'm thinking your "intake valve inlet" is the Intake Air Tube which will also set those codes.

Look across the back of the intake for a vacuum hose nipple. There may be one with a cap leaking or missing. Check the crankcase vent hose(s)...left valve cover to intake air tube and right valve cover to upper intake manifold(left=front, right=rear).

Fuel with too high of an alcohol content, low fuel pressure or restricted injectors can also contribute.
THE PURGE VALVE, I know exactly where this is at! Good stuff, and i actually have a catch oil can due to all the oil that the crankcase vent hose throws into the air tube. Buick problems, haha
 

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If you have checked/verified all of the engine-related items (including cleaning the MAF sensor and verfiying it is good), my next suggestion would be to monitor fuel pressure while driving. It's about the last thing left to verify and it can throw the codes if the pressure is low. The easiest way to do this is to buy an OBDII scanner (there are tons of choices out there, including cheap apps that you can download to your phone, then buy a cable to hook the phone to the OBDII port) that allows you to monitor while driving. The only other thing I can think of that I haven't seen or read is to check for a pre-O2 sensor exhaust leak.
 

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Discussion Starter #11
BadAV said:
If you have checked/verified all of the engine-related items (including cleaning the MAF sensor and verfiying it is good), my next suggestion would be to monitor fuel pressure while driving. It's about the last thing left to verify and it can throw the codes if the pressure is low. The easiest way to do this is to buy an OBDII scanner (there are tons of choices out there, including cheap apps that you can download to your phone, then buy a cable to hook the phone to the OBDII port) that allows you to monitor while driving. The only other thing I can think of that I haven't seen or read is to check for a pre-O2 sensor exhaust leak.
Wow, good information, I am going to look into this! I will get back with the outcome!
 
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