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Author Topic: True ME7.5 Speed Density  (Read 74747 times)
BlackT
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« Reply #60 on: April 10, 2022, 01:49:18 AM »

Thank you very much, will do that  Wink
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kacperoooni
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« Reply #61 on: April 10, 2022, 10:38:19 AM »

I backed to the speed density issue. I found out that map sensor signal isnt too slow. The VE model via KFURL was wrong. I corrected it at it worked really well, at least when the temperature outside was steady. It seems that me7 (hfm one) lacks of rl_w IAT correction when we inject ps_w direcly from map sensor. It result in rl_w to rl_sol overshoot when its hotter and undershoot when its colder. Ofc this map can be implemented without a problem but at this moment forcing maf me7 to speed density makes no sense.
« Last Edit: April 10, 2022, 10:41:28 AM by kacperoooni » Logged
nyet
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« Reply #62 on: April 10, 2022, 12:21:45 PM »

There is no speed density in ME7. Only alpha-n, end of story. Unless you are saying you implemented your own in ASM, including temp correction. You can also fiddle with the IAT parts of the ps/rl rl/ps paths. There are a few already there all in maps, but you'd have to modify the who ftbr stuff probably.
« Last Edit: April 10, 2022, 12:23:32 PM by nyet » Logged

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kacperoooni
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« Reply #63 on: April 10, 2022, 02:12:15 PM »

There is no speed density in ME7. Only alpha-n, end of story. Unless you are saying you implemented your own in ASM, including temp correction. You can also fiddle with the IAT parts of the ps/rl rl/ps paths. There are a few already there all in maps, but you'd have to modify the who ftbr stuff probably.

Read my older posts please. I've already implemented reading ps_w from second map sensor in intake manifold. Rewrote part of BGRSM. Basically, he problem is that ps->rl conversion is made only using pirg_w, fpbrkds_w and fupsrl_w. There is IAT correction, so if you tune KFURL to rl meet your rlsol it its OK until conditions changes (IAT for example). I think that's because MAF sensor is including IAT factor itself.  Prj didnt say a thing about it so I dont know if I do something wrong or what.
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nyet
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« Reply #64 on: April 10, 2022, 02:27:34 PM »

Understood. The stock ps/rl rl/ps conversion does, in fact, have IAT correction built in. Even though the MAF has IAT correction baked in, rlsol converts to pssol with IAT correction in ftbr, so inverse (ps to rl) should do the same, with "real" ps going into ps_w.

If it isn't, take a closer look at ftbr/fwft - there is a single fixed scaling in ASM (along with KFFWTBR and FWFTBRTA) which you can fiddle with.
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nyet
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« Reply #65 on: April 10, 2022, 02:52:18 PM »

Also maybe i have this wrong, but instead of feeding real a ps into ps_w, shouldn't you run real ps through vpsspls correction, then the ps->rl path via fupsrl to get a rl you can feed into rl_w directly? Unless i'm misunderstanding how people typically do speed density in ME7 (i've never done it personally, just have some ideas on the theory).
Sorry if i'm late to the party i confess i haven't fully been following the thread.
« Last Edit: April 10, 2022, 02:54:42 PM by nyet » Logged

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kacperoooni
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« Reply #66 on: April 10, 2022, 03:18:07 PM »

Also maybe i have this wrong, but instead of feeding real a ps into ps_w, shouldn't you run real ps through vpsspls correction, then the ps->rl path via fupsrl to get a rl you can feed into rl_w directly? Unless i'm misunderstanding how people typically do speed density in ME7 (i've never done it personally, just have some ideas on the theory).
Sorry if i'm late to the party i confess i haven't fully been following the thread.

In OEM Speed-density ME7 (2.5 NA) its directly written into psdss_w (which is written directly to ps_w). I have to investigate more how temp correction is done in that ECU. Thanks for the tip with ftbr. I see that in BGTEMPK there is a switch speeddensity/hfm for correction using KFFWTBR or KFWTBR. In hfm ECU (1.8t) its axis is rl, for dss ECU its axis is ps. I think thats the reason I lack temp correction

@edit ftsr is used only when coverting rl->ps. That is the second reason I Think

« Last Edit: April 10, 2022, 03:42:37 PM by kacperoooni » Logged
nyet
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« Reply #67 on: April 10, 2022, 03:43:21 PM »

In OEM Speed-density ME7 (2.5 NA) its directly written into psdss_w (which is written directly to ps_w)

ah and rl then comes from ps_w instead of MAF/RPM, and then used for fueling? Or is rl never used for fueling decisions in speed density? Makes no sense to me.

in any case, if ps_w is used to determine fueling, ps_w itself should not be temp corrected, something else needs to temp correct it to get an accurate air mass out of it, whether in speed density or not.
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kacperoooni
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« Reply #68 on: April 10, 2022, 04:04:58 PM »

ah and rl then comes from ps_w instead of MAF/RPM, and then used for fueling? Or is rl never used for fueling decisions in speed density? Makes no sense to me.

in any case, if ps_w is used to determine fueling, ps_w itself should not be temp corrected, something else needs to temp correct it to get an accurate air mass out of it, whether in speed density or not.

I didn't dive that deep into it. I think that rl is used for fueling in 2.5.

The problem I refer is that when IAT is 7 celcius ps_w on idle is 300mbar, when IAT is 40 celcius ps_w on idle is 400mbar. When I make rl meet rlsol using kfurl on 300mbar idle, rl is higher than in reality when its 400mbar   As the result idle start oscillating and stft goes -%. I don't know whether it is also connected to tmot or not.

If I don't find answer I will just add another map with factor for rl_w based on IAT/tmot and nmot
« Last Edit: April 10, 2022, 04:10:41 PM by kacperoooni » Logged
prj
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« Reply #69 on: April 11, 2022, 04:08:39 AM »

There is already temperature correction according to ideal gas law.
Your problem is that your IAT sensor gets heatsoaked and reports wrong value on idle... Standard charge temp issue.
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BlackT
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« Reply #70 on: April 11, 2022, 05:26:10 AM »

Try to turn you TB for 90° IAT will be less heatsoaked
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kacperoooni
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« Reply #71 on: April 11, 2022, 06:58:58 AM »

There is already temperature correction according to ideal gas law.
Your problem is that your IAT sensor gets heatsoaked and reports wrong value on idle... Standard charge temp issue.

Heatsoak on stock plastic-covered iat sensor?
Is there a way to software deal with it?


@edit prj can be right because I've just checked WOT runs logs and parameters are ok
« Last Edit: April 11, 2022, 07:08:55 AM by kacperoooni » Logged
Blazius
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« Reply #72 on: April 11, 2022, 09:01:06 AM »

There is a Ford sensor that read 200-3000mbar btw with vacuum pipe connection, perfect for this conversion. Its what I have and doing stuff with.
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kacperoooni
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« Reply #73 on: April 11, 2022, 09:44:30 AM »

There is a Ford sensor that read 200-3000mbar btw with vacuum pipe connection, perfect for this conversion. Its what I have and doing stuff with.

Map sensor is not a problem. I have tries couple of vag sensors and all od them are fast enough. Main problem is iat heatsoaking on idle. I wonder how its done on mafless files with alpha-n. On the worst case ill make switch to make idle work alpha n and the rest on map
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prj
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« Reply #74 on: April 11, 2022, 10:12:21 AM »

Map sensor is not a problem. I have tries couple of vag sensors and all od them are fast enough. Main problem is iat heatsoaking on idle. I wonder how its done on mafless files with alpha-n. On the worst case ill make switch to make idle work alpha n and the rest on map
Exactly the same problem on alpha/n.
Been a while since I looked at ME7, I don't remember anymore how the charge temp modelling worked or how advanced it was.

You either model the charge temp or hope that closed loop takes care of it.
And btw no IAT correction map is going to solve your idle issues.
The simplest charge temp model is a map where IAT and Coolant temp comes in and charge temp comes out. This charge temp is then additionally blended via flow and timers.

The core issue is that there is not enough flow over the IAT sensor where it gets any reasonable reading. It starts reading the temperature of the pipe where it's in (so heat in engine bay) because not enough air flows over it to get a good reading.

But tbh the majority of this issue can be solved in a primitive way by messing a little with TVUB - setting it a little too high and injector size (or rather FKKVS factor) a bit lower.
Then when it gets heat soaked on idle, because of the slightly wrong TVUB it will not go that lean ...

Sorry, not going to dig in FR for charge temp modelling.
« Last Edit: April 11, 2022, 10:17:57 AM by prj » Logged

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