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[Link G4 Plug-In] Cut on MAP limit

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Hello all,

I'm currently observing a strange thing on a Link G4 plug in : I put a MAP limit at 15kPa higher than my boost target.

On WOT engine regularly cut on MAP limit but on my log (max rate 40Hz) the MAP is at the target and don't go over the limit...

So I suppose the MAP signal going quickly over the limit (real or electrical problem ?) but I can't see it on the log. At this moment ignition timing match the value of a higher MAP value...

Did somebody ever face to this ?

I will add a log as soon as I can.



I would check what you have set in the main fuel setup and how you have spaned the Y-axis in your fuel and ignition table. What fuel model do you using? Traditional or modelled fuel?

Are you sure that you are hitting the MAP limit and not a GP limit?

+1 for checking your y-axis. MAP vs MGP can cause some confusion.

There is a control range for the MAP limit function in the Link ECU. By default this is 10 kPa which means that the ECU will start boost cutting 10 kPa before the value in your boost limit table. You can adjust this by setting Advanced Mode to ON. This has caught me out on a few occasions and is my best guess as to what is wrong.

Boost control is in MAP and boost limit also so no confusion on this point.

Thanks Andre I checked my data, the cut is always when MAP reach 10 kPa below the limit. There is no information about default setting in the Link help...

I will try the Advanced Mode soon ;)

It's a setting Link changed a few years back. The same thing actually happens with the engine rpm limit too. By default the rpm soft cut begins 200 rpm below the set point in your table. It's just a case of the control range for both of these limits occurring before the actual set point rather than after as we would normally expect. The key from Link's perspective is that using this technique the boost will never exceed the MAP limit you've set as this is where the hard cut occurs.

Yes I saw it for RPM, so I set both MAP & RPM limit in Advanced Mode, it works well ;)

I also took the opportunity to calibrate a smoother RPM limit.

Thank you.

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