car running lean?
Thread Starter
Racer
Joined: Nov 2006
Posts: 311
Likes: 2
From: glenside pennsylvania pa/ la
car running lean?
well i just got done driving my car 1300 miles. I drove from louisinana to philly. Now my check engine light is on. i pulled the codes and it was p0171 and p0174. I looked the codes up and its says system is running lean. Im wondering if i got bad gas form 7 11 becuase it happned after filling up there. i reset the code and it came back on 5 mins later. Im thinking i need to replace fuel filter first and see what happens. Any other suggestions? if i dont reply back becuase have hard time getting on internet fiances gets pissed
Melting Slicks
Joined: Sep 2006
Posts: 2,041
Likes: 4
From: Rockford Illinois
well i just got done driving my car 1300 miles. I drove from louisinana to philly. Now my check engine light is on. i pulled the codes and it was p0171 and p0174. I looked the codes up and its says system is running lean. Im wondering if i got bad gas form 7 11 becuase it happned after filling up there. i reset the code and it came back on 5 mins later. Im thinking i need to replace fuel filter first and see what happens. Any other suggestions? if i dont reply back becuase have hard time getting on internet fiances gets pissed
I have had that code several times. My 02 sensors went to junk after that. What bank is it running lean on?
Melting Slicks
Joined: Aug 2006
Posts: 2,167
Likes: 11
From: Powell TN
Cruise-In VIII Veteran
3rd Gear
Joined: Feb 2007
Posts: 3
Likes: 0
Hey had the same thing with mine,after checking all the usal stuff found that theres a small tube under the T/B that has the pvc attached to it, and the bottom of the hose had got soft and had a hole in it hence sucking air. check that you dont need to go buy the pvc at the auto parts store just get small pice of 3/8 rubber tube about 4 inchs long and put you old pvc on the hook it up and your problem should go away mine did.
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Race Director
Joined: Jul 2004
Posts: 16,794
Likes: 62
From: Lake Havasu City, AZ
Mine did that once after buying a tank of BP gasoline.
If the gasoline happens to be a little high in ethanol content you can throw a lean code.
It went away after I put the next tank of Shell V-Power in ...
If the gasoline happens to be a little high in ethanol content you can throw a lean code.
It went away after I put the next tank of Shell V-Power in ...
Instructor
Joined: Jul 2006
Posts: 137
Likes: 1
From: Litchfield Park AZ
I'm getting the same thing...however mine has shown up differently.
I replaced a bad MAF, then had the PCM retuned. It does not come on frequently. Before today it had only happened twice in a 2 week period since the tune. Those two times it would happen after shutting the motor down then restarting just a few minutes later.
Today however, I made about 10 passes down the 1/4 and got it several times...but for the most part just after I had shut down and restarted not too long afterwards.
I'm going to double check some of the items you guys have already mentioned, but I think I'm all good there.
Any other ideas?
I replaced a bad MAF, then had the PCM retuned. It does not come on frequently. Before today it had only happened twice in a 2 week period since the tune. Those two times it would happen after shutting the motor down then restarting just a few minutes later.
Today however, I made about 10 passes down the 1/4 and got it several times...but for the most part just after I had shut down and restarted not too long afterwards.
I'm going to double check some of the items you guys have already mentioned, but I think I'm all good there.
Any other ideas?
Racer
Joined: Mar 2003
Posts: 440
Likes: 7
From: Willow Park Texas
Those codes are for the long term fuel trim. The MAF measures the amount of air coming into the engine. The computer then knows how much fuel it needs to add to get the proper fuel air mixture. The first O2 sensor is then used to see if the mixture is correct ( This is called closed loop. The fuel mixture will be adjusted to get the correct O2 reading). Over time the long term fuel trims are changed to reflect what the engine requires. If these values get to be to large, the code is set. Since you are getting that it is too lean on both sides of the engine, this would indicate that the MAF is not reading the correct amount of air ( very unlikely ) or the engine is getting air from a source that is located after the MAF has measured the amount of air. ( Very likely ) 99% sure you have a vacuum leak after the MAF. Look for vacuum lines that either have come off or have a hole in them. PCV connection would be the first place I would look along with the connection for the power brake booster. Both of these would suck ALOT of air and cause the codes to be thrown. The leak is there, just keep looking until you find it.
Reb
Reb
Team Owner
Joined: Mar 2004
Posts: 58,476
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From: Oklahoma City OK
C6 of Year Finalist (appearance mods) 2019
Instructor
Joined: Jul 2006
Posts: 137
Likes: 1
From: Litchfield Park AZ
OK, I think I found my problem. I'll try and keep this short, but it does take some explaining.
First I changed my intake manifold to an LS6. While I was at it I changed to the LS6 valley cover as well, in hopes that it would cut down on the amount of oil going into the manifold from the PCV system.
Well, I was still getting oil into the manifold and it was suggested that I put a breather in place of my oil fill cap. Instead of doing that I uncapped on of the old points on the valve cover and put a breather there instead.
Turns out the motor was sucking a whole bunch of air through there and so the MAF was not reading all the air being pulled into the motor from there.
So I put a vacuum cap back on and lean condition is so far all gone. Did multiple test with engine restart, high acceleration etc and no repeats of lean code kicking out.
I'm hoping all is well now.
Thanks for the advice.
First I changed my intake manifold to an LS6. While I was at it I changed to the LS6 valley cover as well, in hopes that it would cut down on the amount of oil going into the manifold from the PCV system.
Well, I was still getting oil into the manifold and it was suggested that I put a breather in place of my oil fill cap. Instead of doing that I uncapped on of the old points on the valve cover and put a breather there instead.
Turns out the motor was sucking a whole bunch of air through there and so the MAF was not reading all the air being pulled into the motor from there.
So I put a vacuum cap back on and lean condition is so far all gone. Did multiple test with engine restart, high acceleration etc and no repeats of lean code kicking out.
I'm hoping all is well now.
Thanks for the advice.
