Fuel trim help please

Hey guys, my LTFT's are staying at -19.5% and at idle the STFT's are pulling another -10% or so.
I just got it back from tuning last week and the bank 1 stft's were a little lean and I ended up replacing the intake manifold gaskets.
After that, both banks have been really rich. I can't find anything physically wrong with the truck. All I can find online is that too high fuel pressure
or stuck injectors could cause it. I've checked both and they're fine. Is there anyone who could take a look at my tune and a log and see if they see any
issues that could cause this? Thanks in advance for any help you can give.

'06 6.0, 223/226 .600 lift 112 LSA cam, PRC stage 2.5 5.3 heads, TBSS intake with 2010 Camaro gold blade throttle body and xlink.Attachment 110674Attachment 110675

If you had a vac leak trims would have been positive... had the VE or MAF table been altered from stock?

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Originally Posted by Ben Charles

If you had a vac leak trims would have been positive... had the VE or MAF table been altered from stock?

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I did initially have a vacuum leak, that?s why I ended up replacing the gaskets. After was when the trims went negative. I don?t know what the tuner did to those tables. I was hoping someone here could tell me if they looked right.

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Originally Posted by Nickpisp

Hey guys, my LTFT's are staying at -19.5% and at idle the STFT's are pulling another -10% or so.
I just got it back from tuning last week and the bank 1 stft's were a little lean and I ended up replacing the intake manifold gaskets.
After that, both banks have been really rich. I can't find anything physically wrong with the truck. All I can find online is that too high fuel pressure
or stuck injectors could cause it. I've checked both and they're fine. Is there anyone who could take a look at my tune and a log and see if they see any
issues that could cause this? Thanks in advance for any help you can give.............

'06 6.0, 223/226 .600 lift 112 LSA cam, PRC stage 2.5 5.3 heads, TBSS intake with 2010 Camaro gold blade throttle body and xlink.Attachment 110674Attachment 110675

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...........Each to their own mate but i do disable LTFT....the VE Map definetly could do with some work to bring it in closer on part throttle in terms of fuel trims (STFT) If going to use them only or unless you use LTFT+STFT calculations etc and anything above part throttle will need a wideband

Sounds to me like

- you had a vacuum leak (lean) with positive fuel trims
- instead of finding the mechanical issue, fuel was added until the trims were in line
- intake leak was fixed, now the ECM sees that its rich, and the trims are pulling fuel

So, if Im reading/thinking correctly, your tune just has too much fuel in it because it was tuned with a vacuum leak.

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Originally Posted by ultimate lsx tuning

...........Each to their own mate but i do disable LTFT....the VE Map definetly could do with some work to bring it in closer on part throttle in terms of fuel trims (STFT) If going to use them only or unless you use LTFT+STFT calculations etc and anything above part throttle will need a wideband

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I’ve paid a tuner for this but he says it’s the truck, not the tune. I don’t know much about tuning. I wasn’t even logging the LTFT’s until it started throwing codes. Just trying to figure out if it’s the tune or the truck.

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Originally Posted by davidchristian83

Sounds to me like

- you had a vacuum leak (lean) with positive fuel trims
- instead of finding the mechanical issue, fuel was added until the trims were in line
- intake leak was fixed, now the ECM sees that its rich, and the trims are pulling fuel

So, if Im reading/thinking correctly, your tune just has too much fuel in it because it was tuned with a vacuum leak.

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That’s what I’m thinking but my tuner says it’s my truck. I can cause a vacuum leak and it’ll improve enough to stop throwing codes.

Time to get a new tuner

Im with Ben on the new tuner part. Also, if you can purposely cause a vacuum leak and it straightens out the fuel trims, you diagnosed your problem already. It was tuned improperly (with a vacuum leak)

Thanks guys