Hey guys, a few weeks ago I broke a valve spring on the pssenger side then sortly after the repairs were done I started getting the following code..

P0171 - Fuel Trim System Lean bank 1-B, Drivers side

After starting the car up, and allowing it to idle for about 2 minutes it immediately idles like ****, and throws the lean code.. The car runs fine in open loop, but once in closed loop, its runs like crap..

Current mods on my 2004 Z06 with 16,500miles:
Long Tube Headers, Tune, Vararam Intake, Crane Dual Springs, t-stat..

I removed the plugs, and found the drivers side to be completely black, and the passenger side spark plugs to be in good condition.. Im going to guess that while the car thought it was running lean it was running real rich (correct assumption?)

-I replaced the 02 sensors, code still present..
-I swapped the 02 sensor lines, and the code pops up on the drivers side no matter what.. (so the lines are safe, no issues with wiring)..
-I replaced the MAF, code still present..
-Opened up the ECU, no water present..
-Had a compression and leakdown test done on the car, results were perfect, motor is in great shape..
-I recently had my shop reflash the ecu so that I run the stock program after the header company suggested that it might be my tune.. Code still present..

I unplugged the front 02 sensors (so the car runs in open loop) and drove the car around and aside from running really rich, the car has no issues, runs pretty well.. With the 02 sensors plugged in up front, the car will stumble on its on with just a little throttle application, throws the lean code, misfire codes every so often, and seems like it wants to die.. At WOT, the car runs like crap..

Last night I removed the drivers side header, and found the following.. I was just wondering if this was was a large enough crack to cause a lean code?

I really don't know what else to check after this (maybe injectors?).. There was no soot around the header/head connection, but to ensure its not a leaking gasket Im replacing the drivers side once I can get my hands on one... The headers have been on the car for over 6months, and never once gave me an issue and as far as I know were not removed during the valve spring repair..

I have been told that it was probably an exhaust leak which is why I pulled my headers off..

I have no more ideas left as to what can be causing a lean code to be thrown.. Remember, the lean code will get thrown with the car just sitting there at idle and does so once the car goes to closed loop.. It doesn't take any serious engine load to get the lean code.. Any help/suggestions are greatly appreciated.. I don't know what else to do, and the shops that Ive talked to are out of ideas..


Thanks..

 

Had a similar problem but, my car went totally rich on one bank.
Turned out to be a bad coil.
And I think the exsessive richness burned up my RT cats. The car exhaust smells like crap now.

 

before reading the entire thread. i was going to say check the header on the driver side. then again, you are getting mixed issues...the driver side plugs should've been white if you were running lean. id swap the coil packs, get new plugs, reset the ltrims and get that crack on the header fixed. fresh air will cause the o2 to give bad readings.

 

BTW
Which headers are those.
I also had a small crack in my set of LGM headers at a weld joint which looked very similar to yours.

 

LG headers

 

That's what I thought.
There does appear to be a quality control issue with these headers. As both of ours cracked in the exact same spot.

 

id call louis up and talk to him about it. Id suggest taking it to a muffler shop right now and getting it welded if you cant afford for it to be down.

 

Well.. I replaced the drivers side header gasket with the one LG supplied, did nothing.. Within 2minutes of letting the car idle, the 0171 code popped up.. Next up is swapping the injectors.. After that, ill try and check the AIR system.. Man is this annoying.. Id much rather have a tranny blow up then have to go through this nonsense..