Stfts going lean issue

[watisthistwo]

Hey guys,

Having an issue where my stfts are going lean when WOT, however, after resetting the kam everything looks perfect, but after some more driving, it starts to go lean up top again. Trying to figure out what the issue could be. Going to replace my O2 sensors, check compression, and hopefully, check for any vacuum leaks. I imagine my fuel system is fine considering after the kam reset its able to keep up with the same RPM/Boost used prior to the reset.

Lund told me to check my fuel system prior to me resetting the kam but after the kam reset and everything looking good I have yet to follow up.

Also, I've had random cylinder misfires after a 2-3 pull which I assume was due to leaning out. Already replaced spark plugs.

Attached (here) are 3 wot logs - 52 is prior to kam reset, 54 is a few miles after kam reset, and 55 is a day after kam reset.

D1x(12-13lbs), ID1000s, fore dual pump w/465s, boss mani, .28 gapped plugs, headers w/ffe, stock compression. Thanks for any help!

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[pittzy23]

I was under the impression that STFTs only really matter when is closed loop (idle, steady rpms, etc.)? under these conditions the STFTs should be around zero (0) +/- 5%. at WOT (open loop) the computer is just commanding a target AFR / lambda and ignores the closed loop fuel trims (STFTs). looking at the beginning of your first log, the STFTs seem pretty stable around the 1% mark, but at WOT in the higher RPMs you are seeing lambda in the low 0.70s, high 0.60s, which seems quite rich. figured high .70s / right around .80 lambda for a boosted application is kinda where things should be. Hopefully someone more confident / experienced with fuel systems can chime in to correct me / help you out.

Update: your lambda in logs 2 and 3 look much better.

 

[Cory S]

There is no open loop on Coyotes (unless forced during tuning) except for when the O2’s are warming up at start up. STFT’s are active and O2’s are reading lambda at WOT as well.

Your STFT operational range is about 10%. ( .90 - 1.10 )

 

[Angrey]

There is no open loop on Coyotes (unless forced during tuning) except for when the O2’s are warming up at start up. STFT’s are active and O2’s are reading lambda at WOT as well.

Your STFT operational range is about 10%. ( .90 - 1.10 )

I thought during "power enhancement" it takes from the set tuning tables and doesn't run closed loop. It still has inputs from various sensory inputs (like knock sensors) but all of it can either be worked around or disabled.

 

[Cory S]

I thought during "power enhancement" it takes from the set tuning tables and doesn't run closed loop. It still has inputs from various sensory inputs (like knock sensors) but all of it can either be worked around or disabled.

Since 2011, they have been closed loop fueling at WOT. Copperhead PCM is amazing. .

 

[ProChargerTECH]

Anything + or - 5% is considered perfection. Then anything + or - 10% is really really good. (Since weather or fuel ethanol content can cause swings.)

 

[Basspro302]

Did you just install the fuel system?

 

[watisthistwo]

Haven't been able to test anything yet been super busy this week, but I appreciate everyone's responses!

Anything + or - 5% is considered perfection. Then anything + or - 10% is really really good. (Since weather or fuel ethanol content can cause swings.)

Good to hear, still concerning that STFTs are trending higher tho.

Did you just install the fuel system?

Just reinstalled it a few weeks prior to those logs. Re-mounted the controller and changed the pumps/socks out for newer ones.

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