getting CEL from fuel trim lean
Thread Starter
Intermediate
Joined: Apr 2008
Posts: 43
Likes: 0
getting CEL from fuel trim lean
hey, i have a 06 z06. i bought it with 4,000 miles on it last year. the CEL would randomly come on, but not for long, and it would only be when i would park it on steep inclines. id run a fuel system cleaner through it and it would go off after 15-20 mins of driving after the fuel system cleaner was put in. then it would stay off for several months.
later i added a set of magnaflow magnapacks, the killer bee II, and the jim hall tune on the sct tuner. now the light started coming on more often and for longer. i finally came around to using the sct tuner to tell me what was wrong and the CEL is from P0171 and P0174 (if i remember correctly). they are both fuel trim lean codes.
anyone know how to tune it a little richer or do i just need to scrap the hand held tune business and take it to a real tuner? i was planning on waiting until i scrapped the magnapacks and put on a set of headers before getting it tuned. id hate to get it tuned now and then have to re do it when i go to headers in the near future.
any recommendations?
oh, and edit to add: i never checked the codes before i put the tune on. so, i really dont know what the previous CEL was for. im guessing it was for the same, but im thinking i should remove the tune and see if the CEL reappears, and check the code then.
later i added a set of magnaflow magnapacks, the killer bee II, and the jim hall tune on the sct tuner. now the light started coming on more often and for longer. i finally came around to using the sct tuner to tell me what was wrong and the CEL is from P0171 and P0174 (if i remember correctly). they are both fuel trim lean codes.
anyone know how to tune it a little richer or do i just need to scrap the hand held tune business and take it to a real tuner? i was planning on waiting until i scrapped the magnapacks and put on a set of headers before getting it tuned. id hate to get it tuned now and then have to re do it when i go to headers in the near future.
any recommendations?
oh, and edit to add: i never checked the codes before i put the tune on. so, i really dont know what the previous CEL was for. im guessing it was for the same, but im thinking i should remove the tune and see if the CEL reappears, and check the code then.
Last edited by biggfroggy; Sep 14, 2011 at 05:52 PM.
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
I had the same codes on my 06 C6 A6. I would reset them and they'd come back every 2 weeks. I am running headers along with a Calloway CAI. I did the following:
1) Re-installed the radiator shroud and used black gorilla tape to hold it in place tightly. GM came out with a TSB saying if you got these codes to check the radiator shroud since it was allowing unusual airflow into the air inlet to the engine.
2) I had added an air/oil separator, so I added 4 hose clamps to the ends of the rubber hoses leading to and from the separator. (could have been a vacuum leak)
3) I re-tightened the intake manifold (I had it off a while ago for porting). Kind of surprised me that some of the bolts were a little loose.
4) I cleaned and re-oiled (lightly) the air inlet filter.
5) I cleaned the MAF with MAF cleaner.
OK, I did this over 2 months ago and I haven't had the codes. So which thing that I did fixed the problem? I have NO CLUE! But all the things I did were easy to do and most needed to be done.
1) Re-installed the radiator shroud and used black gorilla tape to hold it in place tightly. GM came out with a TSB saying if you got these codes to check the radiator shroud since it was allowing unusual airflow into the air inlet to the engine.
2) I had added an air/oil separator, so I added 4 hose clamps to the ends of the rubber hoses leading to and from the separator. (could have been a vacuum leak)
3) I re-tightened the intake manifold (I had it off a while ago for porting). Kind of surprised me that some of the bolts were a little loose.
4) I cleaned and re-oiled (lightly) the air inlet filter.
5) I cleaned the MAF with MAF cleaner.
OK, I did this over 2 months ago and I haven't had the codes. So which thing that I did fixed the problem? I have NO CLUE! But all the things I did were easy to do and most needed to be done.
Former Vendor
Joined: Mar 2004
Posts: 3,442
Likes: 18
From: Winchester CA
hey, i have a 06 z06. i bought it with 4,000 miles on it last year. the CEL would randomly come on, but not for long, and it would only be when i would park it on steep inclines. id run a fuel system cleaner through it and it would go off after 15-20 mins of driving after the fuel system cleaner was put in. then it would stay off for several months.
later i added a set of magnaflow magnapacks, the killer bee II, and the jim hall tune on the sct tuner. now the light started coming on more often and for longer. i finally came around to using the sct tuner to tell me what was wrong and the CEL is from P0171 and P0174 (if i remember correctly). they are both fuel trim lean codes.
anyone know how to tune it a little richer or do i just need to scrap the hand held tune business and take it to a real tuner? i was planning on waiting until i scrapped the magnapacks and put on a set of headers before getting it tuned. id hate to get it tuned now and then have to re do it when i go to headers in the near future.
any recommendations?
oh, and edit to add: i never checked the codes before i put the tune on. so, i really dont know what the previous CEL was for. im guessing it was for the same, but im thinking i should remove the tune and see if the CEL reappears, and check the code then.
later i added a set of magnaflow magnapacks, the killer bee II, and the jim hall tune on the sct tuner. now the light started coming on more often and for longer. i finally came around to using the sct tuner to tell me what was wrong and the CEL is from P0171 and P0174 (if i remember correctly). they are both fuel trim lean codes.
anyone know how to tune it a little richer or do i just need to scrap the hand held tune business and take it to a real tuner? i was planning on waiting until i scrapped the magnapacks and put on a set of headers before getting it tuned. id hate to get it tuned now and then have to re do it when i go to headers in the near future.
any recommendations?
oh, and edit to add: i never checked the codes before i put the tune on. so, i really dont know what the previous CEL was for. im guessing it was for the same, but im thinking i should remove the tune and see if the CEL reappears, and check the code then.
Melting Slicks
Joined: Oct 2010
Posts: 2,220
Likes: 16
From: Sugarhill Ga
As long as the intake hasn't been off (Fast) check to make sure all clamps on the pipping are tight, sounds like you have an air leak. Do not beat on the car until you fix the lean condition or Bad Stuff will happen.
Le Mans Master
Joined: Dec 2005
Posts: 7,002
Likes: 1,687
From: Southeast TX
I had a 174 code that showed up recently with no changes to the motor for 2.5 years. There was a cracked vacuum port plug on an unused vacuum port. I'm sure the cracks would get wider as the motor heated up. Cleared the code, replaced the plug and all is good. It couldn't have been a very big leak, but I guess it doesn't take much.
2nd Gear
Joined: Oct 2011
Posts: 2
Likes: 0
vacuum port
where was that vacuum port you were talking about? I'm running lean and can't seem to find the leak either. I have Halltech superbee on, but that's not it. I checked it for leaks with starting fluid and got nothing, are there any other place you know of where a vacuum leak is common?
