# Fuel trim data



## Ashtonswindle (Nov 6, 2020)

I’m trying to narrow down issues with my fuel trims but I can’t find any of the information I need. What is the acceptable map reading at idle? What is an acceptable maf reading at idle? What should throttle position sensor say at idle? Does anyone know where I can find the exact specifics about this stuff? I just want to know if I’m in the ball park. My fuel trims are so weird and inconsistent and I can’t figure out what it is all the help would be appreciated


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## Mr_Pat (Mar 7, 2021)

Are you tuning yourself ?? Which Software ?? I would point you toward someone but few people I have seen using HP Tuners software tuning themselves appear to have been inactive for a bit now ..


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## Ashtonswindle (Nov 6, 2020)

Mr_Pat said:


> Are you tuning yourself ?? Which Software ?? I would point you toward someone but few people I have seen using HP Tuners software tuning themselves appear to have been inactive for a bit now ..


No I’m already tuned through trifecta but these **** fuel trims are driving me crazy. I know they say don’t fix it if it’s not broke but it scares me. No DTC’s or adverse symptoms except bad gas millage and this odd ticking noise when accelerating that sounds similar to a cricket


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## Thebigzeus (Dec 2, 2018)

I have big negative long term on my BNR tune, everytime I ask about it it's ignored. You have the same issue?


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## Mr_Pat (Mar 7, 2021)

Evap purge maybe ?? I have trifecta as well and havent had any issues .. though I spend most of the time with the Cruise control on for economy until I want to play around.


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## Ashtonswindle (Nov 6, 2020)

Thebigzeus said:


> I have big negative long term on my BNR tune, everytime I ask about it it's ignored. You have the same issue?


Yes!! I reached out to trifecta and even sent them logs and they said everything looks fine and within normal range even though -9 to -14 LTFT is not normal range. I would understand running a little rich on a tune just because they want the extra gas in there but not that rich


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## Thebigzeus (Dec 2, 2018)

Ashtonswindle said:


> Yes!! I reached out to trifecta and even sent them logs and they said everything looks fine and within normal range even though -9 to -14 LTFT is not normal range. I would understand running a little rich on a tune just because they want the extra gas in there but not that rich


Yep, exact same issue! I wonder if they do that to make it run real rich so they dont risk a lean condition and engine damage...


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## Ashtonswindle (Nov 6, 2020)

Mr_Pat said:


> Evap purge maybe ?? I have trifecta as well and havent had any issues .. though I spend most of the time with the Cruise control on for economy until I want to play around.


I actually just read something about a bad evap purge causing ticking and negative fuel trims. That also may explain why my EVAP I/M never completes I’ll have to look into that


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## Ashtonswindle (Nov 6, 2020)

Thebigzeus said:


> Yep, exact same issue! I wonder if they do that to make it run real rich to they dont risk a lean condition and engine damage...


I guess that would make sense but it still bothers the hell out of me. I think I’m gonna take a look at my evap purge tonight or tomorrow


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## Thebigzeus (Dec 2, 2018)

Mine seem to get worse as the engine warms up...


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## Mr_Pat (Mar 7, 2021)

I bought a used Autocal so I can data log and view without having to send to them first.


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## Thebigzeus (Dec 2, 2018)

Mr_Pat said:


> I bought a used Autocal so I can data log and view without having to send to them first.


Yep, love having my own. Can get data right when I get home and on my PC as well. Or see it live.


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## Mr_Pat (Mar 7, 2021)

Thebigzeus said:


> Mine seem to get worse as the engine warms up...


Huh I'll have to log mine and take a look. My mileage hasnt been stellar by any means but has basically stayed around 30 -35 MPG I drive a mix of highway / city daily 40 miles each way.


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## Ashtonswindle (Nov 6, 2020)

Mr_Pat said:


> I bought a used Autocal so I can data log and view without having to send to them first.


I wish I would have done that I just didn’t even think about that


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## Mr_Pat (Mar 7, 2021)

I picked one up on ebay for $110 and Zeus and JLL helped me out figuring out the PID info you need to set up for the data logging .. I had a thread on the forum here somewhere when I asked about the info. 

here autocal config


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## JLL (Sep 12, 2017)

Rich is *much* better than lean. During boost conditions my long term fuel trims are -6 to -12 too. I think most tuners do this to avoid a lean condition if the boost pressure surges.


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## Thebigzeus (Dec 2, 2018)

JLL said:


> Rich is *much* better than lean. During boost conditions my long term fuel trims are -6 to -12 too. I think most tuners do this to avoid a lean condition if the boost pressure surges.


Sure, but -20 ltft's? That's taking a lot out. I guess it begs the question of why that much is there to begin with.


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## JLL (Sep 12, 2017)

Thebigzeus said:


> Sure, but -20 ltft's? That's taking a lot out. I guess it begs the question of why that much is there to begin with.


That is excessive. A code will set if it gets over 25%.


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## Thebigzeus (Dec 2, 2018)

JLL said:


> That is excessive. A code will set if it gets over 25%.


Mine must be turned off then lol. Found a boost leak at throttle body last night during a test though. Maybe that was the issue.


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## JLL (Sep 12, 2017)

Thebigzeus said:


> Mine must be turned off then lol. Found a boost leak at throttle body last night during a test though. Maybe that was the issue.


Interesting


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