I've been trying to figure this p0171 out forever it seems. I have had cyl. 2 misfire as well so I replaced all spark plugs with OEM ac delco ones, put a new injector in cyl 2... new vacuum lines for supercharger bypass... new intake... new MAF... resealed valve cover and pcv line... is there something I'm missing? Or could the Throttle Body be causing this?? BTW the engine light comes on and off randomly.

 

Aftermarket intake?

 

ive had this randomly ever since aftermaket intake...(cheapo from ebay)

 

Ebay intakes will cause this. The only thing you can do is buy name brand..

 

It's a K&n intake

 

Oh thought the other guy was the op. Check for vac leaks. after the maf especially

 

Will do. Last question about this, can the S/C bypass valve (the one stacked right next to the emission canister) suck in excess air through the little foam filter if it's shot?

 

nahh, mines missing lol

id say get a tune and not have that problem

 

Well I have a piece of microfiber cloth zip tied over that stupid hole for now
But anyways, I went through every last vacuum line... tightened my intake down with a wrench, resealed the MAF with a little bit of silicone grease... took it for a test drive. No CEL but it still sounds like it's misfiring at idle. (spark plugs are proper heat range and gap, coils were cleaned couple weeks ago) And it's only making the infamous 7psi... maybe a little more if i really slam on it.

 

I have the same issue.. Althoguht I have replaced all of that, and a throttle body, and both o2's and stillhave the same problem.. I'm out of opptions lmao.. I wish you luck if you find anything let me know please, I'll be sure to do the same for you.

 

Any abnormal hissing sounds?