I have been seeing this more and more and starting to get a little tired of it even though it does seem to help supply me with business as every vehicle I get that has been getting remote tuned or tuned by other tuners in general has had this table zeroed out... THIS IS THE WRONG WAY TO DO IT and has the ability to cause engine damage for a couple of reasons... I honestly don't think tuners know what this table defaults to or does with just simple hot restarts... DO NOT ZERO THIS OUT!!!
During a (HOT NORMAL RESTART) - Injector tip temp will usually default to 70 degrees Celsius, so lets think about this - you have the table set to zero when it should have something in there - owner goes to show off his FI 800 RWHP Camaro that's pushing 18psi - only now his fueling can be up to 10% lean because everyone seems to forget the other side of this coin and that's all of the other temperatures that are "calculated" within the ECM's logic - SO dudes running 10% lean now pushing 18psi on a 10:1 compression motor that was tuned to the lean side for those wonderful "power numbers" - how do you think it's going to turn out?
During a (HOT RE-FLASH) that we tuners have coined "rich after flash" - ALL calculated temperatures default to 100 degrees Celsius - that's all calculated items like IVT and Injector Tip Temp just for example - Just another reason why zeroing out Injector Tip Temp and making fueling corrections is worthless - it's referencing more tables than just injector tip temp for these "offset" fueling adjustments, so how is zeroing out one table and making corrections going to fix everything...
Now - I was personally taught by Jslic or Scott who originally discovered all of this for us on how to correctly calibrate it, but after struggling with it for a while I made my own changes or way of correcting the data and went from there... I'm not posting any of Scott's formulas, but there are better ways like his of getting this dialed in - if your one of the smart ones out there perhaps you can come up with a better way for everyone...
The way I do it requires a lot of idle time and a few hot restarts while sitting there waiting... I have gone to using fuel trims only for this - allows me to dial in fuel trim switching points to the desired air fuel "stoic" setting... In other words it allows me to shift the "0" or stoic set point for the fuel trims to a 14.7ish afr...
So now were taking IVT, O2 switch points and injector tip temp into account - what about cams, injection timing, airflow, engine compartment temps and so on and so on? I'll keep this as simple as I can, but to sum things up everything changes this table, so to make things consistent and to keep things more in line with temperature swings this is how I do it...
First off - dial in your injection timing as this changes fuel atomization and burn efficiency... After this kill long term fuel trims and change the IVT table to something really close to 1's in the map cells where your engine normally idles - your doing this to help yourself out and keep temperature swings fueling more in line... Picture posted below to illustrate...
Attachment 73066
At the same time your doing that your going to put it into MAF only or SD only if it's a SD tune... Your also going to close the hood so the intake is sucking in air like it normally will everyday of the week - make sure you do that part... ALSO at this time multiply your injector tip temp table by the size increase of your current injectors - in other words if you increased them 50% - take 50% out of the injector tip temp table - this will help things go quicker...
With the engine idling at an elevated 1200 rpms your going to log injector tip temp just like it is in the tune - once the temp comes all the way down to as low as it's going to go - usually 50 to 60 degrees Celsius - this will be where you will make corrections to fueling for here on out... We're running the engine at 1200 rpms for a couple of reasons - First off a lot of engines have lopey cams - lopey cams have overlap at idle which will skew things - Secondly you don't want the injector tip temp fueling corrections staying in each cell for a really long period of time - they shift from one extreme to the next if they do - elevated rpms helps the "self calculations" come back into line much quicker than they normally would...
After you get the MAF dialed into a +/- 1 or 2 percent you can start making corrections to injector tip temp... A .000078s or a .0078ms correction can make a 5% difference in fueling - starting to see why this is so important??????????
It's also wise to have it a little richer on a hot restart - I personally target something from 2 to 5 % richer from the 70 degrees Celsius cells to the 55 degrees Celsius cells where the engine normally operates... Of course this will be dependent on injector sizes and engine setups plus you can't dial things in any better than a .0078ms setting due to the ECM's coding...
Before and Afters shown below...
Attachment 73070Attachment 73071Attachment 73072
Sorry for the long post, but hopefully it'll help some people out - if weather, temperature, traffic, hot lapping or anything like that is changing your fueling and you have different injectors or anything changing airflow through the motor now - you might want to look into this... Again there are better ways of doing it - this way just works for me, but it does take a while - possibly a couple hours just in idle time :/
Originally Posted by GHuggins
Reply With Quote