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Fuel trims!

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Old 07-17-2016, 10:05 PM
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Default Fuel trims!

Alright I've had a nightmare of a time trying to figure out why my truck has intermittent fits of "I feel like having the power of a 2L today"

Ran a compression test a while back, all are within 20 percent of each other except number 2, it was at 140 psi. Average for the rest were 165.

Trucks got 284,000 miles on it, the picture of the fuel trims under 10 percent is at idle, the other is at 2000 rpm no load. I've got exhaust leaks on cylinders 7 and 8 due to broken header bolts.

Do the trims show I've got another air leak? Like for the booster.
Attached Thumbnails Fuel trims!-screenshot_20160717-201628.png   Fuel trims!-screenshot_20160717-201607.png  
Old 07-17-2016, 11:54 PM
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I would fix your known leaks before you even try to start chasing anything else.

Air leaks/exhaust leaks can make fuel trims do the crazy dance all the time, you can't really predict what they might do if you know you have leaks.
Old 07-18-2016, 12:44 AM
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Most people dont realize an exhaust leak can pull as much air in as exhaust leaking out if not more, which as ffdp said plays hell on fuel trims....
Old 07-18-2016, 07:49 AM
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I have a gauge for that
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I personally like to disable the long term fuel trims and just tune by the short term trims.
Old 07-18-2016, 10:05 AM
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The leaks have been there for as long as I've had the truck. The power problem just recently stayed happening
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