Codes P0171 and P0174

[Jamesp]

Bank 1 and Bank 2 too lean

Installed a new AOS during the rebuild as there was oil in the intake tubes

Took the oil filler cap off at idle and there was a little vacuum in the crankcase. 2 fingers and little effort maybe three or four ounces of force to get the cap off, as it was definitely getting pulled by a vacuum when it was removed and installed.

I searched this forum and believe I am looking for a fairly substantial vacuum leak.

Anyone have experience with this?

[JFP in PA]

Originally Posted by Jamesp

Bank 1 and Bank 2 too lean

Installed a new AOS during the rebuild as there was oil in the intake tubes

Took the oil filler cap off at idle and there was a little vacuum in the crankcase. 2 fingers and little effort maybe three or four ounces of force to get the cap off, as it was definitely getting pulled by a vacuum when it was removed and installed.

I searched this forum and believe I am looking for a fairly substantial vacuum leak.

Anyone have experience with this?

The codes are for overly lean conditions on both banks, which would be indicative of an intake air leak in the main intake area (throttle body, plenum connector hoses, etc.) as it affects both sides of the engine.

[Jamesp]

Originally Posted by Jamesp

Bank 1 and Bank 2 too lean

Installed a new AOS during the rebuild as there was oil in the intake tubes

Took the oil filler cap off at idle and there was a little vacuum in the crankcase. 2 fingers and little effort maybe three or four ounces of force to get the cap off, as it was definitely getting pulled by a vacuum when it was removed and installed.

I searched this forum and believe I am looking for a fairly substantial vacuum leak.

Anyone have experience with this?

I employed my un-patented "Jamesp Extreme Super Smoker" which runs on cheap cigars, which has become my current aroma. The leak is on the forward right corner of the engine under the manifold in front of the vacuum reservoir. I cannot see the exact point of exit for the smoke though. Any thoughts on how to proceed?

[JFP in PA]

Originally Posted by Jamesp

I employed my un-patented "Jamesp Extreme Super Smoker" which runs on cheap cigars, which has become my current aroma. The leak is on the forward right corner of the engine under the manifold in front of the vacuum reservoir. I cannot see the exact point of exit for the smoke though. Any thoughts on how to proceed?

Not to be overly obvious, but take it apart and see why it is leaking.

[Jamesp]

I was hoping there might be a common failure in a component in that area. I'm modifying a web cam to see if I can see where the smoke is originating.

[The Radium King]

check the boot that holds the resonance tube in place - it mught be cracked or folded somehow underneath. when you have the resonance tube off check the secondary air injection system - it has a couple of vacuum connections in that area.

[Jamesp]

Originally Posted by The Radium King

check the boot that holds the resonance tube in place - it mught be cracked or folded somehow underneath. when you have the resonance tube off check the secondary air injection system - it has a couple of vacuum connections in that area.

Done. Everything looked good. Tried to blow through the spagetti tubing and all the valves must be closed because there was no airflow. Is it common for the air injection cut off valve or the vacuum reservoir to leak? Could that be the source of the vacuum leak?

[JFP in PA]

Originally Posted by Jamesp

Done. Everything looked good. Tried to blow through the spagetti tubing and all the valves must be closed because there was no airflow. Is it common for the air injection cut off valve or the vacuum reservoir to leak? Could that be the source of the vacuum leak?

Definitely, the vacuum reservoir and its lines are common problems. If you have a hand vacuum pump, you can disconnect the reservoir and pump it down to test it.

[Jager]

I like the "Jamesp Extreme Super Smoker" that's a great idea.

[Jamesp]

Pumped down everything south of the vacuum check valve by connecting a vacuum source (the Extreme Super Smoker in reverse - turning out to be handy) to the check valve itself and pulling a vacuum. pulled the check valve off after about 30 seconds and there was plenty of vacuum. Checked the actuator for the butterfly valve in the resonance tube and it's tight. Can the air injection cut off valve have a constant leak that shows up in a smoke test??? I blew into the tube and that valve is closed at present. Can the butterfly valve stem have a leak?

[petee_c]

Originally Posted by Jager

I like the "Jamesp Extreme Super Smoker" that's a great idea.

I like it too. I've got that I think Harbour freight transfer pump?

Sent from my SGH-I747M using Tapatalk

[tconnarn]

i had the same issue. My AOS was bad, and i also had a kink in one of my boots, which was hidden underneath, and not visible. i also found that there was a hose that came loose below the resonance flap, and a screw had fallen out, which caused it not to work 100%. upon replacing AOS, all 4 boots and clamps, fixing the resonance tube and butterfly valve, and replacing the MAF the codes stayed away. I bought a smoke tester from a local guy who makes them in his garage. here is a link to my thread. i had the exact same codes p0171 & p0174

Replacing Boots (Intake Manifold to Resonance Tube)