[zyNoT]

Im working on a 2250 ISB thats been deleted by a reputable tuner but this truck is experiencing heavier than usual fuel consumption.

I noticed a couple of things - first thing - The turbo is closing to 94% at idle (stock setting) and since its deleted - i dont see why that needs to happen. I watched final fueling and adjusted VGA position while the truck was at idle and noticed by opening the turbo from 94% to 50%, it dropped from 11.5 mg/stroke to 9.5 mg/ stroke. with the amount of idling this truck does - theres no reason to make boost at idle and use the extra fuel so I went searching for the table that controls it but had no luck finding it. 

the tables that control the upper and lower VGT limits had no effect on this so there must be something else - hopefully someone can chime in on what needs to be adjusted to stop the turbo from making boost at idle.

Second thing - I know engineers develop these engines to have the best mix of power / economy within the target guidelines of NOx production but since this engine is deleted and were not worried about NOx production, I was considering making small adjustments to the main SOI increment to slightly advance the injection timing and see what kind of mileage gains / losses come from it. 

My question there is; has anyone jumped into this?

high turbo positions ...

Start by determining what engine mode (warmup, city, highway, scr warmup, regen, high altitude, thermal management, etc.) it is in when making so much boost and when going down roads. Engine likely stuck in one of the SCR or other exhaust warming (choke the turbo at high position to make heat) mode permanently because some1 disable scr or dpf system and ecu cant see SCR temps properly any more.

you can't find the mechanism or map that controls it because you can't even identify what engine mode it is running in, nor what is being applied/requested by the ecu. Your poking around in the dark with huge blindfolds on. Not trying to be meanie or discourage, I used to be same way long time ago but know better now. I though I knew a lot about engine but now I look back and realize it was difference between not knowing how to even spell my own name, to being able to write entire college level book. I had a good teacher who helps most anyone for free that is willing to take time to learn this stuff the hard way like it should be. Problem is that most ppl are not willing to follow that rabbit hole to its end so that they can do things the right way.

soi...

you have way too narrow of mindset there and your statement  "...within the target guidelines of NOx production..." is thinking like a flat earther.

Do you even know what engine running modes to adjust and by how much? Do you know how much EGR gas was being used to delay injection timing? do you know what map is low altitude mode? high altitude? highway run mode? warmup mode? regen mode? - what maps are proper to adjust and if they need advancing because of low egr use,.. or need actually need retarding because you took egr gas away? or by how much?


 -- do you know what is the combustion chamber design? CDI?, PCCI?, HCCI? what modes and where inside the SOI maps it transitions from say PCCI early to PCCI Late?

-- Do you know what the injection spray angles are, and where the SOI setting is that will start to get fuel outside of piston bowl?



-- do u know what compression ratio engine has and how much the compression ratio will sensitize the injection timing spread? At low altitude? at high altitude? in what engine mode?



my point is this...

No, I am not saying all this to dazzle someone with BS or to discourage them. Only trying to help others realize it IS more complicated by large amount if you want to get even remotely close to doing things right way, or even what direction to properly adjust things without a bunch of nonsense backward guessing.



yeah, common rail engines are some seriously complicated bastar#ds these days. lawn-mower thinking of injection timing and stuff like that is no more and long gone in todays engines. You are thinking this thing is simple engine with retarded timing to make less NOX like something made 20 years ago. This thinking is very far out of date for these new diesels. Detonation rate, fuel volatility, internal friction control, piston side-wall deflection and everything else is controlled inside the computer now. Most of these common rail engine, the SOI is NOT retarded at all, but far advanced already for most of its run modes. To say they retarded timing to make less NOx is like saying earth is flat any more, because engine makers stopped doing that long time ago due to new combustion chamber and egr designs. SOI in the engine mappings on normal highway run modes is  any more almost always advanced far forward and the egr gas is used to pull it back into normal spec. Take away the egr gas and factory soi is already too far advanced and causes harm to engine all on its own. It will make too much internal friction and have too high detonation rates. - Some dummy 20 years out of date thinking tuner goes about advancing timing even more based on bad assumptions will always make it even worse. - Sure sign of of bad delete in the making.

Before you pass off everyhting just mentioned as "it ain't that complex", just want to make a tweak or 2...

that ECU does not make Magic corrections to fuel, timing, boost, and all the rest in any of its operating modes that would  normally require egr gas. Thats exactly why you can't understand why its going to 95% on the turbo  at idle,.. because the thing is seriously confused and out of proper engine mode control and everything else I said above... so ... yeah,.. IT IS THAT COMPLEX and until a person realizes all of it, starts to understand it,.. and starts to take off their own blindfold on such simple ways of thinking,.. the only result will be more bad piled onto already unstable bad conditions the engine is running in. This unstable garbage is what makes for high oil temps, high internal engine friction, repeating turbo failures, cracked pistons, blown head gaskets, dropped liners, mystery quirks because ecu is going into run modes it can no longer satisfy and the soup of unstable hack-job tuning is the result. All while the guy who made such tunes argues because he is too simple-minded in his thinking and fails to see the reality that he's got a damn big set of blindfolds on, has no clue whatsoever what he's looking at, starring down 10,000+ settings in one of these new ecu's,... lying to himself, convinced that the earth is still flat and he can just add some bit of injection timing, or fueling, or boost or some other stuff to make it run better,... worsening problems it is going to already have because no one re-programmed ecu for proper non-emissions combustion or even re-tasking the ecu into its proper run modes again after removing the egr gas and exhaust systems that were keeping everything in check.


yeah,.. its like that ... for real,... and why so many engine and trubo problems happen when some1  simple out of date thinking blocks egr gas and disables some sensors + emissions manager or 2 in ecu.

my suggestion ... take the long road. Stop focusing on how do disable junk just enough to barely get away with. It only causes engine harm and grief for the guy who owns it when it blows the liners or head, or pops a turbo. - Those kind of people are a dime a dozen already and hang out on every one of these engine tuning forums as the so-called "Experts" and personally I find it disgusting.

The final answer is "yes" there are people who have figured this stuff out in all its detail and glory. -- the right way... it takes time and dedication towards wanting to learn it. - Thankfully though, one of the people who does understand all of this stff in every detail also helped myself and a few others get to where we are at now. He helps people for free as long as they are willing to listen, discuss, and learn it the hard way without being closed-minded. The guy who does the "egr tune-up" series on youtube + his own forum comes to mind when it comes to the ISX/red engine world and I used to think the guy was full of it too,.. but I have since learned otherwise.

I could not agree more with this long but detailed statement. I look back at when I first started before I really understood how these engines do what they do and it really is like learning another language. It's like looking at things you wrote in high school vs now. I'm lucky enough to have people who support me and have the ability to learn things quickly and testing definitely goes a long way. If you have your own truck you can test much more throughly with more time to spend monitoring what the engine is doing as someone else drives it down the highway. You can look at what modes it is switching to, look at timing, look what the IFC is commanding, etc. It REALLY REALLY helps. It is good to start with a baseline of people who are willing to help you get to this point. It really is very overwhelming at first, almost like you don't know where to start. Start with removing emissions equipment from the vehicle by disconnecting any emissions-related sensor. Then find each emissions manager, each sensor resource location, each bitmask, etc and make the changes needed. Check vectoring and make sure the engine is going into the right modes and at the right times when needed. You may want to lock it into CHI-4, or maybe still have a high altitude mode with different mapping, it's all wide open and leads to really making a nice running engine. As Marajin has said, and I cannot stress it enough, you really have to spend the time to get it right, don't half-ass it.