[Z06] Dumb Question ???
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
The only way you will see them with a "C" is to check for codes while the engine is running. Once the engine is shut-off, they become "H" (History) codes.
It could be the Current code you saw was one of the now History codes you listed above. If a current code clears itself while driving, it will then become a History code.
Just completed a 80 mile frwy. cruise at 70 mph - after approx. 40 miles the CEL came on so I ran the diagnostic while driving - " keep your eyes on the road and your hands upon the wheel " 
During the Automatic mode I noticed a CURRENT code in the 10-PCM category but did not see it that well to remember it ? So when it went into Manual mode I scrolled through and it was gone - WTF ! but the Old HISTORY codes were back again:
10 PCM - P0171 H
10 PCM - P0174 H
So after I cleared them ( while still driving ) the CEL went out
Your thought ?
During the Automatic mode I noticed a CURRENT code in the 10-PCM category but did not see it that well to remember it ? So when it went into Manual mode I scrolled through and it was gone - WTF ! but the Old HISTORY codes were back again:10 PCM - P0171 H
10 PCM - P0174 H
So after I cleared them ( while still driving ) the CEL went out
Your thought ?
Last edited by ZeeOSix; May 13, 2012 at 02:58 PM.
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
P0171 Fuel Trim System Lean Bank 1
P0174 Fuel Trim System Lean Bank 2
Bank 1 = driver's side cylinders
Bank 2 = passenger's side cylinders
Look for air leaks after the MAF sensor ... like where the intake connects to the throttle body.
And make sure the MAF sensor is clean and working correctly. Trash the K&N and get a good paper filter.
P0174 Fuel Trim System Lean Bank 2
Bank 1 = driver's side cylinders
Bank 2 = passenger's side cylinders
Look for air leaks after the MAF sensor ... like where the intake connects to the throttle body.
And make sure the MAF sensor is clean and working correctly. Trash the K&N and get a good paper filter.
Last edited by ZeeOSix; May 14, 2012 at 03:00 AM.
Drifting
Joined: Dec 2010
Posts: 1,254
Likes: 7
From: Columbus Oh
I had a similar situation happen to me about a year ago. My CEL came on, when i checked the codes, i had P0171 H and P0174 H. I cleared them and drove for a while and it was fine then the CEL would come back on and same 2 codes. I cleared them then a while later they would come back. The engine sounded fine and i checked all the clamps for the CAI and it all seemed ok so i went round and round clearing the codes then they would come back after 100 miles or so. A month or so later, i installed an oil catch can it was at that time that i found there was a little crack in the PCV hose. Since removing that cracked hose and installing the catch can i have not had any codes. So i think the hose was allowing just enough of an air leak to cause the problem. This may not be your problem but something to look into. You may also want to make sure all of your clamps are tight on your CAI. Good luck.
Thread Starter
Burning Brakes
Joined: Sep 2009
Posts: 1,084
Likes: 0
From: Huntington Beach California
Thanks GUYS for taking your time to provide me information and lead me in the right direction 
Do you think that I can continue to drive her as I try to find the problem or can this LEAN condition damage something ?
Do you think that I can continue to drive her as I try to find the problem or can this LEAN condition damage something ?
Safety Car
Joined: Jun 2005
Posts: 4,977
Likes: 256
From: St. Louis Missouri
Your car has sensors to adjust the amount of fuel it needs to use at any given time. It has the ability to correct for pretty significant changes in airflow. In other words, cleaning a filter won't cause the lean condition.
The lean condition is most likely related to the intake tubing between your throttle body and the airbox. I suggest inspecting that very closely, and even if you can't see something obvious, loosening the clamps and making sure the according tube is seated fully on the throttle body and mass air flow sensor. If all of that checks out, you have a vacuum leak and should have someone familiar with LS1s take a look at it for you.
Thread Starter
Burning Brakes
Joined: Sep 2009
Posts: 1,084
Likes: 0
From: Huntington Beach California
[/QUOTE]Your car has sensors to adjust the amount of fuel it needs to use at any given time. It has the ability to correct for pretty significant changes in airflow. In other words, cleaning a filter won't cause the lean condition.
The lean condition is most likely related to the intake tubing between your throttle body and the airbox. I suggest inspecting that very closely, and even if you can't see something obvious, loosening the clamps and making sure the according tube is seated fully on the throttle body and mass air flow sensor. If all of that checks out, you have a vacuum leak and should have someone familiar with LS1s take a look at it for you.[/QUOTE]
Thanks for the advice, I checked and tightened everything already but I will check and tighten again
But my original question still stands = Do you think that I can continue to drive her as I try to find the problem or can this LEAN condition damage something ?
The lean condition is most likely related to the intake tubing between your throttle body and the airbox. I suggest inspecting that very closely, and even if you can't see something obvious, loosening the clamps and making sure the according tube is seated fully on the throttle body and mass air flow sensor. If all of that checks out, you have a vacuum leak and should have someone familiar with LS1s take a look at it for you.[/QUOTE]
Thanks for the advice, I checked and tightened everything already but I will check and tighten again
But my original question still stands = Do you think that I can continue to drive her as I try to find the problem or can this LEAN condition damage something ?
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Drifting
Joined: Sep 2003
Posts: 1,560
Likes: 25
From: Syracuse NY
In terms of driving with lean codes- from what I have heard- occasional lean codes with an aftermarket filter won't be harmful.
There is also an airflow issue turbulence type issue that can cause the code- Halltech makes a honeycomb metal (?aluminum) screen that is put in before the MAF.
Mine threw a few lean codes during an inspection a year ago- so I ended up buying it and I have not have a lean code since.
Might want to try that if you keep getting codes
Thread Starter
Burning Brakes
Joined: Sep 2009
Posts: 1,084
Likes: 0
From: Huntington Beach California
Thanks - some more history, I had ALL the fluids changed by a Corvette shop here where I live and asked them to also clean my K&N intake filter. Prior to this maintenance work the CEL never came and she ran GREAT, but a few months after this work it started to miss and run crappy but the CEL never came on. I knew that the filter could be over oiled so I took the intake apart to clean the MAF, the clamps were pretty loose ( it should have been leaking air with the CEL coming on then ? ), took everything apart, cleaned the MAF and put it back together ( very tight ) and she ran GREAT again but a week later the CEL came on for the first time, that's when I added the Techtron ?
I have read about this screen that could help, but it did not have one originally ?
Baffled
I will check and tighten it again ?
I have read about this screen that could help, but it did not have one originally ?
Baffled
I will check and tighten it again ?
Drifting
Joined: Sep 2003
Posts: 1,560
Likes: 25
From: Syracuse NY
The c5 Z06 did not have a screen before the MAF. If the MAF is clean and the connections are tight- I would suggest looking at/trying the honeycomb air screen.
http://www.halltechsystems.com/Hallt...r-p/hc.125.htm
I had my stinger air filter on for several years before I saw the lean codes at all- then last year I got three in two weeks (two were during inspections)- the Dealer wanted to do a 500$ evaluation. I tried the honeycomb- passed inspection and I have yet to see the lean code again
http://www.halltechsystems.com/Hallt...r-p/hc.125.htm
I had my stinger air filter on for several years before I saw the lean codes at all- then last year I got three in two weeks (two were during inspections)- the Dealer wanted to do a 500$ evaluation. I tried the honeycomb- passed inspection and I have yet to see the lean code again
Thread Starter
Burning Brakes
Joined: Sep 2009
Posts: 1,084
Likes: 0
From: Huntington Beach California
Guys thanks for the added info., since it's not my DD I don't move too quick with maintenance work - that darn thing call WORK gets in the way ! As soon as I get a chance I will clean / tighten everything again and see what happens then ? If this does not work I will go with the screen 
Thread Starter
Burning Brakes
Joined: Sep 2009
Posts: 1,084
Likes: 0
From: Huntington Beach California
Thanks - some more history, I had ALL the fluids changed by a Corvette shop here where I live and asked them to also clean my K&N intake filter. Prior to this maintenance work the CEL never came and she ran GREAT, but a few months after this work it started to miss and run crappy but the CEL never came on. I knew that the filter could be over oiled so I took the intake apart to clean the MAF, the clamps were pretty loose ( it should have been leaking air with the CEL coming on then ? ), took everything apart, cleaned the MAF and put it back together ( very tight ) and she ran GREAT again but a week later the CEL came on for the first time, that's when I added the Techtron ?
I have read about this screen that could help, but it did not have one originally ?
Baffled
I will check and tighten it again ?
I have read about this screen that could help, but it did not have one originally ?
Baffled
I will check and tighten it again ?
