Question on lean condition

[pete57]

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

[BR3W CITY]

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?

[pete57]

Originally Posted by BR3W CITY

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.

[mongocanfly]

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..

[truckdude239]

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

[davepl]

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.

[pete57]

Originally Posted by davepl

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?

[mongocanfly]

I run the same style element in mine....no issues...I've seen several other builds with the same style element also

[davepl]

Originally Posted by pete57

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.

[pete57]

Originally Posted by davepl

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..

[mongocanfly]

did you get it dyno tuned when you got it running or are you using a store bought generic tune?

[davepl]

Originally Posted by pete57

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!

[davepl]

Originally Posted by pete57

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?

I doubt it's dirty. Have you tried UNPLUGGING it as I mentioned (while off) and then trying to start and run it?

Most GM computers will operate this way and it allows you to determine if your problem is in the intake pipe or MAF. If it runs better with the MAF disconnected, that's your issue. If it's the same or worse with the MAF disconnected, then you can rule it out. Either way you know something new that you didn't know before.

[pete57]

Originally Posted by davepl

I doubt it's dirty. Have you tried UNPLUGGING it as I mentioned (while off) and then trying to start and run it?

Most GM computers will operate this way and it allows you to determine if your problem is in the intake pipe or MAF. If it runs better with the MAF disconnected, that's your issue. If it's the same or worse with the MAF disconnected, then you can rule it out. Either way you know something new that you didn't know before.

Im gonna try to get it out and drive it tomorrow to see if the codes come back, will try unplugging the maf also. Im hopeing that cracked pcv hose was the problem but we'll see if i get that lucky.

[tbrown5079]

I will try unplugging mine also. Only trouble is we had about 8" of snow here yesterday and I'm not taking it out until the roads are dry. I really don't want to horn in on your thread pete57, but this is so close to my issue I really appreciate the info. tbrown.

[WorkinLonghorn]

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

[pete57]

Originally Posted by WorkinLonghorn

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..

[mongocanfly]

unless its in the tune, id try to remedy that issue before I went to the dyno...

[tbrown5079]

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!

[BR3W CITY]

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.

[tbrown5079]

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

[pete57]

Originally Posted by tbrown5079

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

Yeah, same with mine. Only throws the codes after i drive it for a few miles. Runs great other than that. I was thinking on the bigger air intake pipe and open element also, plus long tube headers on mine, maybe its just not tuned right.?. My 1st time really trouble shooting a newer computer control engine like this.

[pete57]

Originally Posted by BR3W CITY

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

[sprint_9]

What are your O2 sensors like? Are they all hooked up? Each one to the proper side? And is your tune set up for the number of O2 sensors that you have?

[tbrown5079]

I have mine installed just as the harness came back from the tuner. It was a low mileage motor ( 27,000 miles ) so I figured they were ok.I guess there is a chance they could have been marked wrong and are on the wrong side. tbrown