05 STS P0174 and P0171
Posted: Sun Dec 02, 2018 8:40 pm
Decided to take a look at the lean codes this afternoon.
I checked a few things and tightened the clamps on the intake plenum duct.
I did find something. The elbow at the rear of the intake that is part of the PCV system was completely falling apart though the rest looked fine. It was very difficult to access and in a surprising location. Rather than a nipple at the back of the intake as I expected, it seemed like a hard plastic pipe ran out the very center of the intake, which was actually hollow. Hard to describe. That plastic tube in the center of the rear is what I am talking about. Getting the spring clamp off was quite a challenge. Ended up using one of my fancy spring clamp pliers but it still was difficult, as there wasn't that much room to work behind the intake.
Here it is in a mirror. Best I could figure in a pinch was 3/8" fuel hose.
Anyway I tried Tractor Supply but the 3/8" fuel hose they had was rated to 175F and specifically said not for under-hood use. I find the engine bay of these cars particularly warm so that is clearly not a good idea. I ended up at Ace which had some 3/8" marine fuel hose, which I hope is suitable. Held it on with some worm drive clamps. Maybe I should get the right elbow.
Anyway I was hopeful that this was my unmetered air leak. Here's the big ugly fuel hose. What did the road test reveal? Well I used my generic tool which happily displays the datastream pretty quickly using the CAN protocol. That's something.
I put up short and long term trims. The verdict is....I think I have a vacuum leak. Under any kind of load the trims even right out and look great. But under lighter load and overrun, they get ridiculous, though the values are also odd, like +18 on the LTFT but also -12 on the STFT. The short term never seems to be able to really correct the long term in some of these circumstances. But the point is, that seems to rule out anything in front of the throttle body. It's something subjected to intake vacuum, I would assume. That helps narrow it down.
I'll drive it some more. Wonder if I need to do the intake and gaskets...I would probably order a plenum duct just because it would make sense to change. But I'm not ordering parts yet.
I checked a few things and tightened the clamps on the intake plenum duct.
I did find something. The elbow at the rear of the intake that is part of the PCV system was completely falling apart though the rest looked fine. It was very difficult to access and in a surprising location. Rather than a nipple at the back of the intake as I expected, it seemed like a hard plastic pipe ran out the very center of the intake, which was actually hollow. Hard to describe. That plastic tube in the center of the rear is what I am talking about. Getting the spring clamp off was quite a challenge. Ended up using one of my fancy spring clamp pliers but it still was difficult, as there wasn't that much room to work behind the intake.
Here it is in a mirror. Best I could figure in a pinch was 3/8" fuel hose.
Anyway I tried Tractor Supply but the 3/8" fuel hose they had was rated to 175F and specifically said not for under-hood use. I find the engine bay of these cars particularly warm so that is clearly not a good idea. I ended up at Ace which had some 3/8" marine fuel hose, which I hope is suitable. Held it on with some worm drive clamps. Maybe I should get the right elbow.
Anyway I was hopeful that this was my unmetered air leak. Here's the big ugly fuel hose. What did the road test reveal? Well I used my generic tool which happily displays the datastream pretty quickly using the CAN protocol. That's something.
I put up short and long term trims. The verdict is....I think I have a vacuum leak. Under any kind of load the trims even right out and look great. But under lighter load and overrun, they get ridiculous, though the values are also odd, like +18 on the LTFT but also -12 on the STFT. The short term never seems to be able to really correct the long term in some of these circumstances. But the point is, that seems to rule out anything in front of the throttle body. It's something subjected to intake vacuum, I would assume. That helps narrow it down.
I'll drive it some more. Wonder if I need to do the intake and gaskets...I would probably order a plenum duct just because it would make sense to change. But I'm not ordering parts yet.