Going rich then lean when shifting

[dleach1407]

go cut your manifold volume in half should enrich her nicely on tip in

with or without the +10% tip transient fuel?

[decipha]

you have to get manifold volume dialed in first

[dleach1407]

Dropped it from 6 to 3, seems better but its also raining so I couldnt really get into boost. I did a few high rpm shifts and I only saw it dip once but it never dipped into the 20s. I saw 18s once but most times its in the 15s when i shift. Drivability is definitely improving so i feel im finally making progress on this. I might try moving it just a little more but I think its just about there now. I may try it at 2 or 2.5. Its going rich on tipout when shifting, would I adjust decel time constant for that once I am sure the manifold volume is correct?

[decipha]

that or the bottom of the transient table

[dleach1407]

Which transient table are you referring to?

[decipha]

theres only one

fn1321 ottomh

[dleach1407]

Have you thought about doing a transient fuel write up? I dont understand what im changing or how each setting interacts with the other settings at this point with any of the transient settings. If there was a description or explination of what each transient setting did, I feel like I would be able to dial this in based on what they do. .

[dleach1407]

Im sorry to be posting all these questions, I wanted to try and define the settings I believe could be part of the solution. Ive been researching each of these trying to get an idea how they interact with each other and this is what I have gathered. Hopefully the info I have is accurate.

Air_man_vol -> How quickly the accel enrichment (pumpshot) is added? What dictates the amount of pumpshot, is this fixed or based on a FN1321 or 1052?

Equilibrium Intake Surface Fuel (FN1321) -> Transient fuel table (what is the unit of measurement or table reference LB/M of fuel?) I believe this table is used to determine the amount of tip in fuel added based on load and temp and then the time constants dictate how long that amount is added/removed?

Manifold fill VE correction (FN1052) -> No idea what this is used for

MTEISF (Tip In Multiplier) -> No idea what this is used for other than it being a multiplier, my thoughts are if fn1321 is maxed out, you would increase this so fn1321 can be reduced.

Accel time constant (FN1322AL) -> How long the accel transient fuel is active (adds fuel based on fn1321?). I believe this is used to compensate for the difference between the accel enrichment and the remaining fuel needed to maintain stoich. I believe you increase this to add some fuel after the accel enrichment runs outs to maintain fuel film equilibrium. Is that accurate?

Decel time constant (FN1322DL) -> How long the decel transient fuel is active (removes fuel based on fn1321?) I believe this works exactly the opposite of Accel time constant and would be used to remove fuel to maintain fuel film equilibrium while rpms come down.

Please feel free to correct my info and add any other transient fuel settings I missed.

[dleach1407]

Anyone?

[decipha]

I started writing a transient write up many moons ago but it confused more people than it helped since transients are controlled differently on different strats

But there is 3 primary methods, the older accel enrich for the fox, basic load and time on the sn95 and then xtau used on the newer ecus from early 2000 to current 2021.

press f10 or hover the mouse over a parameter to see the comments. If there are none lmk and ill update it

dialing in transients requires trial and error. You have to get the base fuel dialed in first then you first adjust the manifold volume to get the tip in fuel as consistently unchanged as possible. You should be able to get it 95% of the way dialed in with manifold volume alone. Keep in mind manifold volume also largely affect the tip out fuel as well which is not a concern at first. You reduce the manifold volume to enrich the fuel on tip in and increase it to lean it out on tip in.

units for the transient tables doesnt matter. Your trying to compensate the percentage the fuel fluctuates from load to load by applying that percentage correction to the target cell.

fn1052 manifold volume temp modifier is just that. It multipliea the manifold volume scalar for different act and ect temps. You use it to correct tip in fueling when cold.

Best bet is to look at your wideband fluctuation from load to load (cell to cell) and adjust it to minimize the fluctuation.

Another thing unrelated but appears as transient fueling problems is injector lag. Knock off china made injectors are notorious for having slow pintle control and when going from a low on time to a high on time they tend to hang up and stay shut a few cycles before opening what they are commanded to. It can be easily spotted by the AFR going in to the 1.15+ lambda range for a 3 seconds or more when a large transient happens and then it smooths out.

Transients are usually only in that 250 msec time after a load change.