Negative long term effects of adjusting fuel slopes?

[aj2ssrs]

I've been reading alot of posts on this and other forums about using a Trinity/Predator for tuning. I own a Trinity and when I received it last December, I immediately installed the canned 93 tune which made the car run a little stronger. Started to get more comfortable with the unit and read about running logs to dial in the long term fuel trims by adjusting the injector slope. Everything was dialed in after several logs, but I ended up chasing the ltft's because they would change due to variables in weather conditions. I figured this is going to be a PITA to have to log just for the weather. While setting up an appointment to have lt headers with hi-flow cats installed along with a dyno tune, I went over the changes I made with the Trinity and was told that adjusting the injector slope is NOT the right way to tune. For my own curiosity and maybe to save someone major damage down the road, what are the long term negative effects on the engine by tuning this way? Maybe Ted or any other tuners could jump in and let us know.

[06MonteSS]

lol... there will be no damage down the road...

is it the proper way to adjust it when you get a dyno tune, when the full tuning software and dyno tools are available to use? no... but it works...

is it the proper way to adjust it via a handheld, since you could not adjust the entire MAF/VE tables via a handheld? yes...

no other handheld even gives you the option to get your fueling dialed in at all... so your fueling is never correct with theirs...


and, as far as your ltft's go... they will always fluctuate, that's their purpose... the idea of getting them in the 0 to -2 range, is so that they don't fluctuate AS MUCH...

so, pick a good warm day... do a cruising log... check your ltft's... make your adjustment as needed, and that's it... you're done...

if you check 'em every day, yes - you will be chasing your tail... heh...

[aj2ssrs]

Originally Posted by 06MonteSS

lol... there will be no damage down the road...

is it the proper way to adjust it when you get a dyno tune, when the full tuning software and dyno tools are available to use? no... but it works...

is it the proper way to adjust it via a handheld, since you could not adjust the entire MAF/VE tables via a handheld? yes...

no other handheld even gives you the option to get your fueling dialed in at all... so your fueling is never correct with theirs...


and, as far as your ltft's go... they will always fluctuate, that's their purpose... the idea of getting them in the 0 to -2 range, is so that they don't fluctuate AS MUCH...

so, pick a good warm day... do a cruising log... check your ltft's... make your adjustment as needed, and that's it... you're done...

if you check 'em every day, yes - you will be chasing your tail... heh...

If I understand your reply correctly, you're saying it is NOT the proper way to tune using full tuning software on a dyno, but it IS proper to tune using limited resources on the handheld? That doesn't make sense to me but correct me if I'm wrong.
As far as logging is concerned, my initial logs were done during a cold spell in early December. Temps were around 20 degrees. My first log, minus 2 injector slope adjustment was recommended. 1 day and 100 plus miles later, second log recommended another minus 2. Day 3 and another 100 plus miles later and minus 1 is recommended for a total of minus 5 injector slope. No more logs were done for a while and I was looking for something to do so I ran another log for the hell of it. This time it's telling me to add back 2. The only difference between all the logs was the temperature was in the 50's on my last and final log. Same road, same amount of miles driven and same rpm's. This was when I was told that weather conditions do effect the tune when modified this way and that a dyno tune would not be effected by the weather. As you know, living in the Northeast has some huge temperature and humidity changes that can be seen on a regular basis. What exactly is happening to the fuel trims if you dial them in during the summer while it's 95 degrees, and don't redial them in in the winter when it's 10, or vice-versa?

[06MonteSS]

adjust your fueling via the slope adjustment on the handheld, so that your ltft's are dialed in, versus not adjusting your fueling at all and leave things outta whack - then yes, doing it via slope is a work-around way to do it properly, since you can not re-scale the MAF or VE tables via a handheld.

I would need to see your data logs to know what's really going on with them...

normally, during the winter, slope usually only needs to go down about another -1% compared to warmer summer weather... i.e. during warmer/summer weather, mine is set to -4%... and during the colder/winter weather, it's set at -5%... and that's it... any other time of the year, I don't change anything at all with them... because as I mentioned, they will still fluctuate day to day based on temps... but they won't fluctuate as MUCH as they would if you didn't adjust anything at all... will they ALWAYS be in the 0 to -2 range? no, but they'll be pretty damn close when they're not...

[Russell James]

Related question. If a CRM tuner makes a custom mail order tune, are they making adjustments via slope? If you do data logging and see a need for a little fine tuning after a custom tune, would it be better to have the CRM tuner make tweeks or would they just be tinkering with the slope that the user could do?

[aj2ssrs]

Originally Posted by 06MonteSS

adjust your fueling via the slope adjustment on the handheld, so that your ltft's are dialed in, versus not adjusting your fueling at all and leave things outta whack - then yes, doing it via slope is a work-around way to do it properly, since you can not re-scale the MAF or VE tables via a handheld.

I would need to see your data logs to know what's really going on with them...

normally, during the winter, slope usually only needs to go down about another -1% compared to warmer summer weather... i.e. during warmer/summer weather, mine is set to -4%... and during the colder/winter weather, it's set at -5%... and that's it... any other time of the year, I don't change anything at all with them... because as I mentioned, they will still fluctuate day to day based on temps... but they won't fluctuate as MUCH as they would if you didn't adjust anything at all... will they ALWAYS be in the 0 to -2 range? no, but they'll be pretty damn close when they're not...

I did not save my data logs. I erased them after the car was dyno tuned knowing I would not need them anymore. You're saying that re-scaling the MAF or VE tables is the best way to tune the engine, (which was done when my car was dyno tuned), and that tuning with the handheld is a "work-around". Isn't that the opposite of what you stated in your first post?

[06MonteSS]

uuugghhh...

no... not at all....

using the handheld to adjust the slope in order to get the fueling dialed in, is better than not being able to adjust your slope at all, and drive around with your fueling outta whack and not correct.

and when you only have a handheld to do it with, adjusting the slope is a work-around to get the fueling dialed in, instead of messing with the MAF/VE tables. - since you don't have those options or ability to do that with a handheld.

so, then if your car was dyno-tuned already, then why are you worried about slope adjustments again????

[06MonteSS]

Originally Posted by Russell James

Related question. If a CRM tuner makes a custom mail order tune, are they making adjustments via slope? If you do data logging and see a need for a little fine tuning after a custom tune, would it be better to have the CRM tuner make tweeks or would they just be tinkering with the slope that the user could do?

messing with the MAF/VE tables via an email tune without having the vehicle there in front of you, on a dyno, is useless...

[RedJewel2SS]

there's more than one way to skin a cat

[06MonteSS]

EXACTLY!!! ^ ^ ^ ^ ^

I'm done....

[DSteck]

The black and white of it is that raping the injector flow rate table is not the proper way to adjust things. You'll still be reporting inaccurate cylinder airmass and airflow readings which will affect MAF/VE bias, timing maps, and more. The effect will trickle down into other areas. As far as a problem? Drivability that isn't as good as it should be, exacerbated by mods like a cam. You can end up forcing trims to be positive some places and negative elsewhere, which can impact fueling at WOT when starting at partial throttle at various points.

Will you notice any of this? Maybe not. Everyone's ass dyno is a different sensitivity.

[aj2ssrs]

Originally Posted by DSteck

The black and white of it is that raping the injector flow rate table is not the proper way to adjust things. You'll still be reporting inaccurate cylinder airmass and airflow readings which will affect MAF/VE bias, timing maps, and more. The effect will trickle down into other areas. As far as a problem? Drivability that isn't as good as it should be, exacerbated by mods like a cam. You can end up forcing trims to be positive some places and negative elsewhere, which can impact fueling at WOT when starting at partial throttle at various points.

Will you notice any of this? Maybe not. Everyone's ass dyno is a different sensitivity.

I agree. This is also how it was explained to me from a different source and should be avoided.

[aj2ssrs]

Originally Posted by 06MonteSS

uuugghhh...

no... not at all....

using the handheld to adjust the slope in order to get the fueling dialed in, is better than not being able to adjust your slope at all, and drive around with your fueling outta whack and not correct.

and when you only have a handheld to do it with, adjusting the slope is a work-around to get the fueling dialed in, instead of messing with the MAF/VE tables. - since you don't have those options or ability to do that with a handheld.

so, then if your car was dyno-tuned already, then why are you worried about slope adjustments again????

Maybe using the handheld to adjust slope is not better than nothing at all.

I have yet to data log since getting dyno tuned 3 months ago because there is no need to. In my original post I stated that this question was for my curiosity and to find out if there are going to be any problems popping up down the road. Others may choose to use this info and maybe not change their injector slope settings if it could possibly do harm.

Why are you done?

[06MonteSS]

Originally Posted by DSteck

The black and white of it is that raping the injector flow rate table is not the proper way to adjust things. You'll still be reporting inaccurate cylinder airmass and airflow readings which will affect MAF/VE bias, timing maps, and more. The effect will trickle down into other areas. As far as a problem? Drivability that isn't as good as it should be, exacerbated by mods like a cam. You can end up forcing trims to be positive some places and negative elsewhere, which can impact fueling at WOT when starting at partial throttle at various points.

Will you notice any of this? Maybe not. Everyone's ass dyno is a different sensitivity.

again... throwing a cam into the mix... need to get on a dyno...

and I don't know what injector "slope" you adjust and have all those issues, but the only one that I adjust is the "injector flow rate vs kpa", and don't have any issues whatsoever...

maybe you're taking the talk about "slope" literally and are talking about the parameter for Injector Slope fuel flow rate modifier, or the slope iat modifier... but, that's not what I'm talking about...

and as far as driveability?? again, the changes I make, the vehicles (cars/trucks) run smoother and more consistent than they ever did... first words out of people is how amazed they are that their vehicle is running so much smoother, all the way through - and about the response it has now, etc etc etc... but, whatever... I'm not going to get in to a pissing contest here... heh.

Originally Posted by aj2ssrs

I have yet to data log since getting dyno tuned 3 months ago because there is no need to.

how do you know there's no need to?? do you really actually know what your readings are at now, 3 months later?