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Author Topic: Problem with external GearCut device on ME7.5 racecar  (Read 7202 times)
curamrdan
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« on: April 27, 2021, 11:39:43 AM »

Hi, experiencing problem on racecar 1.8t with sequential gearbox, using external box, which cuts power for ignition coils. Issue is, after shifts, ecu goes to some limp mode and WGDC are zero for some limited time - say 10-20sec (boost request is still there, no DTC).
Have you any tips for me?
« Last Edit: April 27, 2021, 01:01:41 PM by curamrdan » Logged
cessnas
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« Reply #1 on: April 27, 2021, 01:44:21 PM »

Probarbly the only way to stop this happening is to numb knock recgonition(See the S4Wiki). This is a really bad idea though since the knock sensor will not do anything even when not shifting, so it can cause serious engine damadge.
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nyet
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« Reply #2 on: April 27, 2021, 02:24:17 PM »

The only "safe" way to do this is somehow signal the ECU to turn off knock recognition during the cut (similar to what some LC/NLS ASM hack functions do), which likely would requiring wiring an input pin and a good amount of ASM.

I would not recommend numbing KR unless this car is always running race gas or E85
« Last Edit: April 27, 2021, 02:26:17 PM by nyet » Logged

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curamrdan
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« Reply #3 on: April 27, 2021, 03:02:19 PM »

There is zero KR during shift cut(maybe already in limp at that moment?). It happends also when i shifting with clutch(=closed throttle, but box still cutting coil power source)
Tried to find any "endstuf" diagnostic codeword for ignition coils, but found nothing in ME7.5(wideband). Will try to rise DZUEET counters, but its just shot in the dark.
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nyet
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« Reply #4 on: April 27, 2021, 03:32:18 PM »

Ah. Then it is not KR related. Probably ignition DTC related.
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justinvw2646
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« Reply #5 on: April 27, 2021, 03:33:34 PM »

Will your box allow removal of ground instead of B+? Might be worth a try to see if it makes any difference.
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BlackT
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« Reply #6 on: April 27, 2021, 08:05:01 PM »

Log would be nice.
Did you change ESKONF?
CL codeword?
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curamrdan
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« Reply #7 on: April 28, 2021, 01:28:59 AM »

Box is simple, just cutting wire feeded into it and potentiometer for time adjustment.
In eskonf means zeroing or 11  ZUEs?  I did not touch it yet, but good idea.
CL codeword, do not know what it is...?

Log is here, first pulls and last pulls are with box disconnected, middle  signle shift is with box connected and only situation when problem happends. All is normal shifting, not flat/wot shift.
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prj
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« Reply #8 on: April 28, 2021, 03:07:40 AM »

Restore all fault classes to stock and the ECU will most of the time literally tell you what the problem is.

Another thing which will cause a load cut is if the ECU sees lean mixture during WOT.
Which it will see, because you're cutting spark, so a ton of oxygen hits the sensor.

And then we get back to the same point.
If you had the skills to solve this, you would not be even using an external box, because the ECU can do this much better based on an input.
Either way what you are trying to do most likely will require code mods to the firmware.
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d3irb
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« Reply #9 on: April 28, 2021, 09:38:40 AM »

Hi, experiencing problem on racecar 1.8t with sequential gearbox, using external box, which cuts power for ignition coils. Issue is, after shifts, ecu goes to some limp mode and WGDC are zero for some limited time - say 10-20sec (boost request is still there, no DTC).
Have you any tips for me?

Strongly recommend you get rid of any external box and look at NLS patches. You basically want to trigger NLS on an external input that happens not to be the clutch pedal (load cell or whatever you're using for sequential shift detection).

The only way you will fix this issue effectively is by editing the software. Editing the calibration is not going to fix this for you without breaking something else. So, you might as well use the existing patches to the software that accomplish what you want.
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curamrdan
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« Reply #10 on: April 28, 2021, 10:13:19 AM »

Tested eskonf coding, and some different settings, none of them had an effect.
When i shift in WOT, seems immediately as cut happends, throttle is closing and then goes back, it looks like normal shifting on log, but it was not.
Tried classic NLS patch some time ago(before car owner installed cutbox), and it was not worked as expected...like it was not cutting fast enought. Its is hewland gearbox with SQS sequential shifter, design of cut switch is not perfect, just my opinion.

So im giving up. 
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curamrdan
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« Reply #11 on: April 28, 2021, 10:22:08 AM »

If i decide to give a NSL patch another shot. How to overcome 2 things?:

1. car has no speed sensor , when i set speed treshold to zero, i will not work if i remmeber correctly.
2. gear cut switch is just momentary ,it will not cover whole time of shifting process like on clutch pedal.
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_nameless
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« Reply #12 on: April 28, 2021, 12:41:07 PM »

If i decide to give a NSL patch another shot. How to overcome 2 things?:

1. car has no speed sensor , when i set speed treshold to zero, i will not work if i remmeber correctly.
2. gear cut switch is just momentary ,it will not cover whole time of shifting process like on clutch pedal.


I have a solution if needed pm me
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BlackT
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« Reply #13 on: April 28, 2021, 12:49:05 PM »

1.You can make NLS routine without speed signal
2. NLS patch work cut ignition for 200 mS, most  drivers can't shift in this range, but still make to shift on WOT, engine does not produce powerr so fast
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prj
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« Reply #14 on: April 28, 2021, 04:37:38 PM »

The NLS patch on here is stupid, designed only to make flames out of the exhaust.
You need a cut based on strain gauge and not one which has timers and what not, but which completely cuts everything out until the shift is complete.
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