DIY tuning

Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
Yeah N55 can't really go below around 1500psi rail pressure without breaking up so just a LPFP upgrade doesn't even really help. I'm pretty sure I could limit boost to around 17 and taper to 12, get AFR a bit leaner, and increase rail pressure request to run E40 reliably but I'd rather run 19 or 20 tapering to around 15 on E30. E40 is only one point higher octane than E30 when mixing with E54 rather than E85.
 

Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
The way I have been working on my Fuel Scalar table is as follows;
- Start with a base value for the fuel I'm running
- Get logs with as many different RPM/Load points as possible
- Look at STFT for those RPM/Load points and adjust as necessary

The problem is it seems the car goes open loop during periods of fast transition. So rather than pouring through logs to look at each data point and compare the actual AFR to the target AFR for that particular RPM/Load point I made a lookup table to do it for me (attached). Copy a log to the 'Log' tab with the same channels as shown (up to 1000 rows unless you edit the 'Main' tab), copy your AFR target table to the 'Fuel Target' tab (both axes need to be descending), and then you can filter the results in the 'Main' tab to your hearts content.

Maybe this approach isn't valid for some reason and if you think it isn't I'd like to hear why but I guess we will see in the logs. I should have my Innovate installed soon as well which should have a greater log resolution.


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Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
Does anyone know what the actual behavior is for Tastverhältnis ab dem das Schubumluftventil öffnet
TVLDUVOS / WGDC to open Diverter Valve? This is 70% in the stock bin, does this mean it will open when WGDC is >= 70% regardless of throttle position?
 

LamboLover

Corporal
Apr 6, 2017
237
Translated German from Bosch:

"The condition that the diverter valve opens is derived from the drive duty cycle above a threshold.
These quantities are usually calculated by the function LDUVST. This is not available in the project, since the duty cycle to
Control of the diverter valve is calculated in a BMW function."
 
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LamboLover

Corporal
Apr 6, 2017
237
From a VAG: "The function %LDUVST determines the operating points for opening the dump valve in case of surge. Opening the dump valve aims a fast reduction of the critical compression ratio in order to avoid surging."
 

LamboLover

Corporal
Apr 6, 2017
237
"Duty cycle recirculation valve" is the value that TVLDUVOS is compared to. I think this may be a duty cycle for the recirc valve not the wastegate unless anyone can confirm it is necessary to raise TVLDUVOS to stop the recirculating valve opening whilst at full throttle.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
950
New York
in reference to tuning. I've seen many people forget this car has a MAF. and most don't even bother calibrating it for whatever aftermarket intakes they have. MAF functionally calculates airflow so if the calibration is off. It will do funky stuff to fueling in different situations.



Does anyone know what the actual behavior is for Tastverhältnis ab dem das Schubumluftventil öffnet
TVLDUVOS / WGDC to open Diverter Valve? This is 70% in the stock bin, does this mean it will open when WGDC is >= 70% regardless of throttle position?
"Duty cycle recirculation valve" is the value that TVLDUVOS is compared to. I think this may be a duty cycle for the recirc valve not the wastegate unless anyone can confirm it is necessary to raise TVLDUVOS to stop the recirculating valve opening whilst at full throttle.

that 1D table is specifically for the BPV/Diverter valve. Which is why I labelled it as such. Has nothing to do with the wastegate or a certain point or duty cycle the wastegate reaches. Originally when I started testing that table I though it was for the amount the BPV opens when activated to relieve Boost pressure possibly to help transient boost response. But I have not seen any change in the opening characteristic of it after making drastic changes.

Thus far, I have not seen a situation for which that table becomes called upon to use. but this was months ago when I first defined it. I may do some more tests on it. But for now, there is no reason to change it. If I find a situation where its used, i'll be sure to let people know.
 

LamboLover

Corporal
Apr 6, 2017
237
It is the minimum duty cycle to the diverter valve for the diverter valve to be considered open enough to diagnose its failure from MAF pulses. It is not used for anything else and has no direct link with wastegate duty cycle. Suggest "Minimum diverter valve duty cycle to diagnose diverter valve". If 100% duty cycle is never used, raising to 100% might have a use in tuning for exotic turbo/bypass valve setups that surge a bit on lifting in which case this part of the diagnosis would be disabled. Alternatively, the vehicle voltage threshold for diverter valve diagnosis UBRUVO could be raised to a higher voltage than could be reached.
 

Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
Thanks for the info. I had raised it based on the label thinking it was opening at WGDC above the value set but didn't see any difference in logs.

Justin, regarding your MAF comment, have you seen a need to adjust MAF values on stock intakes?

Thanks.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
950
New York
Thanks for the info. I had raised it based on the label thinking it was opening at WGDC above the value set but didn't see any difference in logs.

Justin, regarding your MAF comment, have you seen a need to adjust MAF values on stock intakes?

Thanks.

Stock intake, no. As long as there is no leak after the MAF. it shouldn't need any adjustments
 

Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
Thanks. I have my e30 tune dialed in fairly well I think. Going to switch from commanded WG back to the stock boost control now.
 

Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
I turned Commanded WG back on. I just don't understand what needs to be done with the PId system. WGDC occsilates like crazy and I'm not sure where to begin. I'll do some more research and try again.

There's not much more I think I can get out of it though without a bigger Ic and a bigger turbo.
 
Last edited:

Sbrach

Corporal
Platinum Vendor
Oct 2, 2017
224
I've never used JB4 but one thing that I always hear from JB4 users who switch to MHD is that they had less boost taper on JB4 and could carry 17psi to redline. I never understood this because on my custom tune I only manage at most 14psi with WGDC at 100% from 5k up. One thought I just had though is that JB4 controls the boost solenoid directly. I wonder if whatever the DME calls 100% WGDC isn't enough to fully close the WG. Would be nice if someone with access to a car with JB4 and without could scope both of them but I figure that is unlikely. I think I'll tee my vac line and see how much vac im pulling on the actuator at 100% WGDC and then post on N54tech to see if a JB4 user wants to do the same.

Thoughts?

Regardless, I do realize that the turbo is out of its efficiency range and probably won't make much more power at higher boost psi at redline but it would be nice to explain the discrepancy especially for people coming over from JB4 to MHD.
 
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Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
950
New York
I've never used JB4 but one thing that I always hear from JB4 users who switch to MHD is that they had less boost taper on JB4 and could carry 17psi to redline. I never understood this because on my custom tune I only manage at most 14psi with WGDC at 100% from 5k up. One thought I just had though is that JB4 controls the boost solenoid directly. I wonder if whatever the DME calls 100% WGDC isn't enough to fully close the WG. Would be nice if someone with access to a car with JB4 and without could scope both of them but I figure that is unlikely. I think I'll tee my vac line and see how much vac im pulling on the actuator at 100% WGDC and then post on N54tech to see if a JB4 user wants to do the same.

Thoughts?

Regardless, I do realize that the turbo is out of its efficiency range and probably won't make much more power at higher boost psi at redline but it would be nice to explain the discrepancy especially for people coming over from JB4 to MHD.

I'd like to see a log of a JB4 stock turbo car making 17psi at recline on PWG. Every log I've ever seen. 13-14psi with 100% wgdc on JB4 over 6k rpms.

I've posted logs and customers of mine have as well flash only stock turbo over 6k rpms making 15-17psi on PWG. It's all in the tune.

And from everyone's responses to those logs. No one even knew the stock turbo could make that much boost up. Its doesnt increase HP that much. But it carries torque out further in the RPMs.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
950
New York
And I'm not sure what you are insinuating by saying the JB4 has direct control over the solenoid.

The DME has full control over every aspect of Boost control. Far more control than a JB4.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
950
New York
However, dealing with PWGs if pre-load is not set right or the solenoid is leaking vacuum. It will effect Max possible boost since the gate can be pushed open by exhaust flow partially
 

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