Johns00Z28

iTrader: (6)

My service engine soon light just came on the other day and I got the codes diagnosed and it read P0171 and P0174, system too lean on bank 1 and 2. Not sure what this means, can anyone help me figure it out?

2001NBMZ28

Could be a few things - I'd check for a vacuum leak first. www.gearchatter.com/viewtopic9039.php

Johns00Z28

iTrader: (6)

Where could the vacuum leak be coming from? Someone recommended I check the MAF and spray some carb cleaner on it in case some oil from the filter got in it.

Johns00Z28

iTrader: (6)

Well I cleaned the MAF and checked and found the wingnut on my catch can wasn't tightnened so I tightened that. I pulled the pcm ign and pcm bat fuses to reset the pcm but to no avail. The SES light stayed on so I guess I'm going to have to take it by my mechanic to check for vacuum leaks.

BAMALS1

iTrader: (16)

Have you checked the PCV Hose? That is a common place also right where it turns to go the intake under throttle body blade.

Formula413

iTrader: (1)

You can check for vacuum leaks yourself, it's pretty easy. Just get a can of carb cleaner and spray it on and around any and all vacuum lines or anywhere there is vacuum. As someone mentioned, the PCV hose is a leading candidate, these seem to fail often on LS1s. The hoses to and from your catch can are another possibility.

tording99Z28

iTrader: (3)

I had this exact issue not 2 months ago and this is exactly where mine was. I just replaced that little angled piece with some 3/8" vacumn line with some hose clamps to make sure it stays secure and I have not had a problem since. Check here for sure.

Johns00Z28

iTrader: (6)

Well I did the TB bypass mod, would it still be in the same place under the throttle blade?

Johns00Z28

iTrader: (6)

I would try it but I'm a newbie and I'm not sure where all the vacuum lines are.

Johns00Z28

iTrader: (6)

I suppose it's a possibility that the issue lies there then since those lines have been altered and changed not too long ago.