No Device: Does the MAP deceleration curve tell you anything
The Dyno RoomA special room dedicated for Dyno tuning products, troubleshooting and results. All Gearheads and Dyno Operators are welcome here as well as the guys that are new to tuning. Please see the special rules for this section before posting.
This is what happens when you take some of your CDE entries too far and seems to be accompanied by a tell tale sign in the VE table itself. In this case the 1825 and 2250 CDE entries are wrong.
I keep remembering that Steve said that EGR didn't affect MAP readings so will qualify this with, maybe this is a PV foible as with the MAP value at idle discussion a couple of years back.
Anyways, having gone back through my CDE tuning data I can sort of see when things started to go wrong, and the deceleration curve prior to that was more of a smooth curve.
This is what happens when you take some of your CDE entries too far and seems to be accompanied by a tell tale sign in the VE table itself. In this case the 1825 and 2250 CDE entries are wrong.
I keep remembering that Steve said that EGR didn't affect MAP readings so will qualify this with, maybe this is a PV foible as with the MAP value at idle discussion a couple of years back.
Anyways, having gone back through my CDE tuning data I can sort of see when things started to go wrong, and the deceleration curve prior to that was more of a smooth curve.
You need to be careful as the fuel gets turned off in decel at times. So you need to separate decel fuel and decel fuel cutoff points apart or you will begin chasing your tail.
Let me a few more days to find the time to finish working on my CDE tune and I will show you the before and after Decel MAP curve. There is definitly an impact.
Since you can move your VE higher or lower with the CDE, the MAP has to change since the INJ PW remain the same (once tuned).
Let me a few more days to find the time to finish working on my CDE tune and I will show you the before and after Decel MAP curve. There is definitly an impact.
Since you can move your VE higher or lower with the CDE, the MAP has to change since the INJ PW remain the same (once tuned).
You can raise the VE by lowering the CDE table and you can lower VE by raising CDE table. I agree and can follow up to this point. Both of these tables are used to come up with how long to hold injector open. The CDE table just covers more area with a "cell" that makes the number a constant for several of the VE table cells. Why are we making it more complicated than it is by adding MAP into it?
The curve doesn't tell me anything. A bike on a dyno will show you one curve. Might be a bit different on a low inertia dyno. Same as you will different curves in different gears. Also depending on weight of bike and the grade of road. Which way you are traveling. Loaded up bike with mama on the back, to running empty to the store for cigs. You know. All the same things that affect MAP at 15% throttle/ 2500 rpm's.
Edited because the red print is backwards. Brain fart, it happens. Thanks for pointing it out.
...although if you remove the deceleration data that has no fuel ...you are not left with much data at all to form any curve/line/square whatever ...comes back to the basic question, does whatever it looks like mean anything?? or are we barking up the wrong tree??
Deceleration and no fuel is possibly where the old guidance of setting the PV autotune to ignore data with MAP less than 30 or so comes from ...because the PV autotune process is not AI enough to ignore data where there was no fuel??
No fuel is going to make the O2 sensors report blocklocks in regard to the "autotune" trying to calculate a VE
...although if you remove the deceleration data that has no fuel ...you are not left with much data at all to form any curve/line/square whatever ...comes back to the basic question, does whatever it looks like mean anything?? or are we barking up the wrong tree??
Deceleration and no fuel is possibly where the old guidance of setting the PV autotune to ignore data with MAP less than 30 or so comes from ...because the PV autotune process is not AI enough to ignore data where there was no fuel??
No fuel is going to make the O2 sensors report blocklocks in regard to the "autotune" trying to calculate a VE
So let's take this a little further. It takes time for the fuel to reach the engine once it has been turned off and the manifold and heads dry out. Once this happens some of the fuel that would normally go into the engine is then soaked up into the porous material because it's dry. There is a term to this state and it's called "wall wetting" and it has to be accounted for. So the fuel turns on, wall wetting happens and what do you think the O2 are going to report? How do you know when to ignore and when not too, as you can have the conditions both occur at the same MAP reading?
not quite sure that I agree that metal is porous but I get what you mean
What you describe essentially becomes something of a delay factor...?
stop fuel - the airflow absorbs what is on the "wet walls" - O2's tail off to lean
start fuel - and some is lost as the walls wet up again - O2's are initially lean
Is this effect significant on these engines with the injectors hitting the back of the inlet valve?
...at least significant enough that we should know and not chase our tails, I presume
ADD: we're back to you really need a dyno to get good steady state data, huh
04-07-2017, 05:24 AM
Does the MAP deceleration curve tell you anything
