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Discussion Starter · #1 ·
Im trying to get my maf transfer down and I keep noticing that I have a 10% difference between the banks on mt STFT. Im assuming its an exhaust leak since I have degreed my cams and double checked this. The truck put down good numbers on the dyno and I have never been able to find any vac leaks anywhere. From what Ive read, its more than likely a header gasket leak. How can I determine what side its coming from?
The way it sits now, is Bank 1 is the lower one at .80 and Bank 2 will be around .90. How do I know whos the problem side?
 

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Bank 1 Passenger side
Bank 2 Driver's side
 

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Discussion Starter · #3 ·
lol sorry Stew, I got that part. Im trying to figure out what side would have the leak or the issue. Id rather not change both header gaskets.
 

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If you cannot hear the header leak under a load I seriously doubt it is the problem. Also I would be looking aat LTFT's if you are trying to tune based on trims. A more accurate way is to put the truck in open loop so your trims stay at 0 and the adjust the MAF based on AFR without the computer tuning things as you drive.

If it is an exhaust leak the leak will be on the side that is adding more fuel (higher (+) trim) or taking away less (lower (-) trim) because the side with the exhaust leak will be pulling in outside air due to scavenging and the O2 sensor will see that side as the lean one.
 

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Whats your LTFT siting at on both banks.... if its within about 2% you should be ok.
 

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Also if you are tuning in closed loop look at LTFT's and STFT's. Sometimes one will be adding 4% and another pulling 5%. That is why it is better to tune open loop, because then you are looking at the program, not how your comuter is compensating at that moment.
 

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Discussion Starter · #7 ·
Im actaully working on building a tune right now and Im trying to adjust my MAF table. Adaptive is turned off so there are no LTFT on that tune.

I haven't looked at any logs for my regular tune, but I know there is a split between LTFT that is more than 2%.

As for header gaskets, I know everyone says Ford is the best, but that's what I'm running now and I'm not getting the warm fuzzy about reusing them. I read about the copper ones but the Percy dead soft aluminum look better.
 

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If you had a header gasket leak it should not effect the STFT's. The exhaust gases will blow out of the gasket. You might get a very small amount of air being sucked in, but nothing that would effect STFT's to that extent.
 

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Also if you are tuning in closed loop look at LTFT's and STFT's. Sometimes one will be adding 4% and another pulling 5%. That is why it is better to tune open loop, because then you are looking at the program, not how your comuter is compensating at that moment.
Open loop turns off the 02 sensors completley so you dont get short or long term fuel trims. Turning off adaptive allows you to see raw short term trims without any long term learning.

JJ
 

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Discussion Starter · #11 ·
I just remembered this, I used to get a random p0171 bank 1 too lean. A while ago, I re degreed my cams, thinking that was it, but my cams weren't off. I also checked both my headers for leaks, and I tightened each both, all but one were tight.
The only thing I was ever able to find were blown collector gaskets.

Ill have to take a look
 

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Discussion Starter · #15 ·
I ended up having some pretty bad leaks again at the collectors. I had new aluminum gaskets installed and had to re-torque them down. Not this first time this has happened
 
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