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Discussion Starter #1
I decided to remove the stock air resonator box on my dad's 05 Colorado (3.5L inline 5). We drove Saturday night after doing it and I drove it some yesterday with no probs (sounds great too). After driving to work today, he's getting a P0171 code. Could this be caused by replacing that box?
 

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Common sense will say that it does have to do with the new home made resonator.

Take some pictures of it and we can help further.

Every time I see or hear this problem with our GMT 355s, it is due to the installation... EX: Putting a mushroom filter on the valve cover breather or just plain old leaky connections.
 

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Common sense will say that it does have to do with the new home made resonator.

Take some pictures of it and we can help further.

Every time I see or hear this problem with our GMT 355s, it is due to the installation... EX: Putting a mushroom filter on the valve cover breather or just plain old leaky connections.

i agree, most likely a leak after the MAF causing unmetered air to enter the combustion chambers (the MAF doesnt register the extra incoming air so it has no way of knowing to compensate with added fuel, thus a lean condition)
 

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Discussion Starter #6
i agree, most likely a leak after the MAF causing unmetered air to enter the combustion chambers (the MAF doesnt register the extra incoming air so it has no way of knowing to compensate with added fuel, thus a lean condition)
There definitely is no leaking going on--we checked that all out. I can double check it, but I really doubt it leaks. I put a rubber coupler around the pipe then inserted it into the stock tubing and tightened it down.

Do you think that putting a breather filter on the crankcase breather may be the cause? If that is all it is, I can fix that easily. I'll post up a pic tonight.
 

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Discussion Starter #7
Here's 2 pics....





The small hose is the vent for the fuel pressure regulator. It is held in by a rubber grommet and is sealed with RTV and it fits extremely snug in the grommet even without the RTV. As you can see, I do have a breather filter on the crankcase breather.

I'm not new to modding by any means, this just baffles me.

And don't mind the dirty engine bay---too cold to clean it.

Oh, and there is about 40K miles on the truck.
 

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Yup, the breather is the cause of the lean condition. That is the source of external air coming into the engine past the MAF sensor. Pipe that to the new resonator.
 

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The dirtyness of that engine bay shall haunt my dreams for all time.

:lol:
 

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Discussion Starter #10
Yup, the breather is the cause of the lean condition. That is the source of external air coming into the engine past the MAF sensor. Pipe that to the new resonator.
Okay, I'll get that corrected--we had contemplated redoing it anyway


And the engine bay is just because it's my dad and we only did this mod to gain a few extra ponies and maybe help gas mileage a bit like it did for my car. He's 51 and could care less how dirty the engine is. I tried to tell him, but to no avail. :lol:
 

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And the engine bay is just because it's my dad and we only did this mod to gain a few extra ponies and maybe help gas mileage a bit like it did for my car. He's 51 and could care less how dirty the engine is. I tried to tell him, but to no avail. :lol:
Yeah, I kind of figured. I was just giving you a hard time, it's what I do. :lol:
 

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Yeah, I kind of figured. I was just giving you a hard time, it's what I do. :lol:
No worries---this site definitely seems friendlier than some of the other sites I have been on such as j-body.org. Everything there turns into some hissy fit fight.

Thanks for the help everyone.
 

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Discussion Starter #14
I think I fixed the problem. I went to Lowe's and bought a brass pipe fitting and threaded it into the pipe and attached a hose from the breather to the fitting. The pipe is made of aluminum---it is actually a piece cut from an AEM intake from a Hyundai Tiburon (it was free)---so it was easy to drill and tap a hole for the fitting. We drove it around a few times and no light, so I think we got it. It sounds awesome though.

So we managed to get it done for a total cost of around $10. The pipe and the rubber coupler I cut to make the pipe fit into the stock tubing were free. All I paid for was the 2 pieces of hose and the brass fitting---and 2 small hose clamps.
 

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Yeah guarauntee the breather was the issue... it's setup a certain way for a reason the aftermarket can't cover up all of GM's crazy designs and plans :lol:
 

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Discussion Starter #18
I'll clean it up for him come spring time. Once I get back to doing it, I'll be powdercoating that pipe too so it doesn't look so bad.
 

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is that like a pvc pipe or somthing....?
 
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