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bank to bank a bit unbalanced, but my Pilot has had -10 to -16% total fuel trims at idle since we bought it in 2015. Do you have any drivability issues?
 

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Discussion Starter · #3 ·
Just sluggish acceleration, I have changed spark plugs and coils changed transmission fluid, installed a vcm muzzler, cleaned throttle body, changed air filter and cleaned Maf sensor.
 

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The list of usual suspects that cause negative fuel trims is short; over-reporting MAF, high fuel pressure, leaking injector(s), sticking purge valve, excessive EGR. There are YouTube video for checking most of those things. The MAF reading for the Pilot is supposed to be 10.3 ~ 12.5 grams/sec @ 2500 RPM, in Park, A/C and all accessories OFF.

As for sluggish performance, seems lately they are related to cam timing issues due to failing or failed timing belt tensioners. It's not all that difficult to check cam timing--see other threads about timing belts.
 

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Discussion Starter · #5 ·
The list of usual suspects that cause negative fuel trims is short; over-reporting MAF, high fuel pressure, leaking injector(s), sticking purge valve, excessive EGR. There are YouTube video for checking most of those things. The MAF reading for the Pilot is supposed to be 10.3 ~ 12.5 grams/sec @ 2500 RPM, in Park, A/C and all accessories OFF.

As for sluggish performance, seems lately they are related to cam timing issues due to failing or failed timing belt tensioners. It's not all that difficult to check cam timing--see other threads about timing belts.
For some reason I cannot locate any threads or videos on how to check cam timing, would you mind leading me to some?
 

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Just for kicks this afternoon, I was under the hood doing other things (checking refrigerant charge) and decided to measure fuel pressure now that I have the means to do it. 55 psi key on, engine off (12.5v to pump). Nominal is 61psi running (13.7v to pump). So that isn't why my Pilot has negative fuel trims--fuel pressure on the lower end of nominal would offset my fuel trims, somewhat positive.

Not purge system, nor EGR. That leaves leaking injector(s), which I doubt as it doesn't run rough after sitting for a few hours. Injectors were rail cleaned a year ago. No change in trims. So that leaves over-reporting MAF and possibly some mechanical thing I've never found. It had a TB job and valve adjustment at the dealer, pretty recently, in case anyone tries that bunny trail.
 

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Discussion Starter · #8 ·
Just for kicks this afternoon, I was under the hood doing other things (checking refrigerant charge) and decided to measure fuel pressure now that I have the means to do it. 55 psi key on, engine off (12.5v to pump). Nominal is 61psi running (13.7v to pump). So that isn't why my Pilot has negative fuel trims--fuel pressure on the lower end of nominal would offset my fuel trims, somewhat positive.

Not purge system, nor EGR. That leaves leaking injector(s), which I doubt as it doesn't run rough after sitting for a few hours. Injectors were rail cleaned a year ago. No change in trims. So that leaves over-reporting MAF and possibly some mechanical thing I've never found. It had a TB job and valve adjustment at the dealer, pretty recently, in case anyone tries that bunny trail.
I went on a quick drive today with my scan tool today and noticed far better fuel trim numbers while driving
 
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