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Old 03-16-2018, 10:02 PM   #1
pete57
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Question on lean condition

I did the 5.3 swap in my 64 last summer and it turned out good. It starts fine idles fine runs great but I keep getting the lean condition codes on both banks. It does buck and fart some when I really get in it. My question is will it be ok to keep driving it while im trying to figure it out? I don't want to maybe do any damage, but I love driving it and don't want to have to park it till I fix it. Been trying to find a tuner in my area but have came up with nobody so far. Thanks
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Old 03-17-2018, 01:44 AM   #2
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Re: Question on lean condition

If your going so lean its backfiring while driving, I think you already know the answer to this. No, don't drive it.


What codes is it setting off?
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Old 03-17-2018, 10:04 AM   #3
truckdude239
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Re: Question on lean condition

Could be bad intake gaskets thats what it is on my c10 with 4.8 ls swap been driving that way for awhile and no issuses so far i really need to do them
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Old 03-17-2018, 10:39 AM   #4
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Re: Question on lean condition

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Originally Posted by BR3W CITY View Post
If your going so lean its backfiring while driving, I think you already know the answer to this. No, don't drive it.


What codes is it setting off?
Codes are P0171 bank 1 and P0174 bank 2 too lean condition.
It runs great normal driving,idles smooth, never gets hot, the only time it did backfire is when i put it on the floor one time.
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Old 03-17-2018, 11:26 AM   #5
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Re: Question on lean condition

check for air/vacuum leaks...hoses, intake gaskets, around maf....might also be o2 sensors.....make sure your o2 sensor plugs arnt on the wrong sides..
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Old 03-17-2018, 11:39 AM   #6
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Re: Question on lean condition

Does this engine have the air meter (MAF, or mass airflow sensor)?

If so, try unplugging it. Does the engine run a lot better? Then you're MAF pipe needs help, some kind of air straightener, etc. Or just run it with the MAF disconnected in speed density mode, I think that's a valid choice too.
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Old 03-17-2018, 01:06 PM   #7
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Re: Question on lean condition

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Does this engine have the air meter (MAF, or mass airflow sensor)?

If so, try unplugging it. Does the engine run a lot better? Then you're MAF pipe needs help, some kind of air straightener, etc. Or just run it with the MAF disconnected in speed density mode, I think that's a valid choice too.
Yes, it has the MAF. Ive tried cleaning it a couple of times but no change. I do have on open element on it, could it be getting too much air?
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Old 03-17-2018, 01:18 PM   #8
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Re: Question on lean condition

I run the same style element in mine....no issues...I've seen several other builds with the same style element also
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1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
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Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 03-17-2018, 05:44 PM   #9
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Re: Question on lean condition

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Yes, it has the MAF. Ive tried cleaning it a couple of times but no change. I do have on open element on it, could it be getting too much air?
Please try what I suggested - unplug the MAF and see if it runs better.

I think your MAF is likely just not calibrated to that pipe/filter/intake combination. Which is almost a given if you're not using the late model truck's entire intake pipe.
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Old 03-17-2018, 07:03 PM   #10
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Re: Question on lean condition

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Originally Posted by davepl View Post
Please try what I suggested - unplug the MAF and see if it runs better.

I think your MAF is likely just not calibrated to that pipe/filter/intake combination. Which is almost a given if you're not using the late model truck's entire intake pipe.
Ok, ill give it a shot. Sooo, if i do this and it fixes it, what then? Do i leave it unplugged, or try to get it tuned/calibrated? Got my harness and pcm from PSI and they put one of their "tunes" in there based off what i told them i had.
Thanks for the help..
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Old 03-17-2018, 07:46 PM   #11
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Re: Question on lean condition

did you get it dyno tuned when you got it running or are you using a store bought generic tune?
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1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 03-17-2018, 11:35 PM   #12
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Re: Question on lean condition

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Originally Posted by mongocanfly View Post
did you get it dyno tuned when you got it running or are you using a store bought generic tune?
Generic tune from PSI. Told them what i was running and they sent me a pcm. I have been wanting to get it tuned but cant find anybody local, gonna have to drive a couple of hours to get to one looks like. Didnt know if it would be ok to drive it that far throwing these codes.
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Old 03-17-2018, 11:51 PM   #13
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Re: Question on lean condition

we have a couple of dynos in Huntsville and one in Decatur if that helps you any..not to awful far from you...bout a hour or so
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1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 03-18-2018, 11:54 AM   #14
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Re: Question on lean condition

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Originally Posted by pete57 View Post
Ok, ill give it a shot. Sooo, if i do this and it fixes it, what then? Do i leave it unplugged, or try to get it tuned/calibrated? Got my harness and pcm from PSI and they put one of their "tunes" in there based off what i told them i had.
Thanks for the help..
It's complicated, but I'll give you a brain dump on what I went through on mine and how I fixed it if it turns out to be the same problem. Let me know what you find out when you try it!
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Old 03-18-2018, 11:56 AM   #15
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Re: Question on lean condition

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we have a couple of dynos in Huntsville and one in Decatur if that helps you any..not to awful far from you...bout a hour or so
Yeah, Lane Culver is the guy i was wanting to go with. Ive got a few friends that have been to him. Who else in Huntsville would you recomend?
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Old 03-18-2018, 02:16 PM   #16
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Re: Question on lean condition

Lane was who I used...and would again....bunch of guys I work with are into rock bouncing and he's the only one they'll use....the day before I was there Big Chief from street outlaws had the crow on his dyno....you could still smell the nitro
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1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 03-18-2018, 06:59 PM   #17
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Re: Question on lean condition

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Lane was who I used...and would again....bunch of guys I work with are into rock bouncing and he's the only one they'll use....the day before I was there Big Chief from street outlaws had the crow on his dyno....you could still smell the nitro
Yeah i heard that. He must be pretty good.
Thanks..
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Old 03-18-2018, 07:05 PM   #18
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Re: Question on lean condition

Cleared the codes and checked for vacuum leaks, didnt find any yet. Fuel pressures at 58# so i guess thats ok. Ill try unplugging the maf and take it for a drive next, see if they come back. Think it would be ok to drive it an hour or so to get it tuned or need to trailer?
Thanks for all the help so far..
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Old 03-18-2018, 07:21 PM   #19
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Re: Question on lean condition

If it was my baby, I would not drive it with lean codes especially since you said it bucks and farts. It's just not wise IMO.
What did PSI say when you informed them of the problem? -BA
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Old 03-18-2018, 08:19 PM   #20
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Re: Question on lean condition

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If it was my baby, I would not drive it with lean codes especially since you said it bucks and farts. It's just not wise IMO.
What did PSI say when you informed them of the problem? -BA
Have not contacted them. Figured id look for something simple first.
Only bucked and farted once only at wot, otherwise it runs great.
Think id lean towards the safer side too. Thanks..
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Old 03-18-2018, 10:17 PM   #21
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Re: Question on lean condition

unless its in the tune, id try to remedy that issue before I went to the dyno...
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1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 03-21-2018, 10:08 PM   #22
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Re: Question on lean condition

I will be interested to see how you make out on this issue pete57. I have the same issue and haven't been able to solve it. Replaced the intake gaskets and have searched for any other leaks, but no luck. Mine runs fine and is strong, but it seems like after 50 or 60 miles of driving it sets both the PO171 and PO174 codes. I reset the ECM and after I drive it 50 or 60 miles it throws the codes again. I am going to record the mileage next time and see if it is constant. I may try unplugging the MAF sensor also. Good Luck!
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Old 03-22-2018, 10:53 AM   #23
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Re: Question on lean condition

It would be interesting to see Logs on this. I'm wondering if its triggering the lean codes only under certain load conditions...I'd like to see what those are. IF you clear the codes and just idle it in park, does it still trigger the codes? or does it only happen when revving or attempting to drive.
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Old 03-22-2018, 12:24 PM   #24
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Re: Question on lean condition

I use my truck just as a means of transportation. Trips to the hardware, walmart, cruise around town or go see a friend. never wot. It runs great. After I drive it several times (50 miles or so ) just as I am putting it away, I notice the check engine light is on. If you look at my buildsite, I do have a 180 degree bend in the intake pipe from the air cleaner. Full 4" pipe, but could that cause an issue with the MAF sensor that would trigger a lean condition? Also, it doesn't seem like I am getting real good gas mileage and smells rich when I pull it into the garage. Puzzling, and I would like to get it resolved, which is why I was interested in pete57's post. Thanks for the come back. Maybe we can both learn something. tbrown
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Old 03-22-2018, 01:09 PM   #25
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Re: Question on lean condition

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Originally Posted by BR3W CITY View Post
It would be interesting to see Logs on this. I'm wondering if its triggering the lean codes only under certain load conditions...I'd like to see what those are. IF you clear the codes and just idle it in park, does it still trigger the codes? or does it only happen when revving or attempting to drive.
Cleared the codes and just moving it back and pulling forward some and idleing and reving it some has not triggered the codes again yet. Does have a rich smell. i did find and replace the boot on the pcv valve was cracked, it was sucking air, but would that set off both banks? I have a scanner but dont know how to read data on it, just clear codes
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