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Author Topic: 24V VR6 stock inlet cam adjustment map looks wierd  (Read 2584 times)
larppaxyz
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« on: April 24, 2020, 04:04:25 AM »

Can someone explain why masterminds at the Car Factory mapped intake camshaft to work like this? I verified this from two stock ECUs. These engines have variable inlet cam, exhaust cam with two positions and variable intake manifold (SU, two positions, switchover around >4000).

What i have seen in on internet, usually these maps are very linear.

EDIT : OK, i think my map is mirrored. Noticed right after posting this and cant remove. (no its not)

However, there still is huge spike down there. Second picture added.

« Last Edit: April 24, 2020, 05:28:25 AM by larppaxyz » Logged
larppaxyz
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« Reply #1 on: April 25, 2020, 12:13:04 AM »

Few definitions i had, all marked these maps to be 16x18. That is how WinOLS detects them by default, maybe that is why and nobody checked.

Map size seems to vary between different ECU's greatly and same map is used in many different ways (for example Audi 1.8T VTT).

Now knowing that and looking at those pictures i added, it seems that there are actually 8 rows in this map...
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nyet
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« Reply #2 on: April 25, 2020, 12:17:47 AM »

I agree. I would not make any assumptions about the accuracy of your map definition (or any one else's for that matter, including the tuners)

Three lessons:

1) never use anyone else's file as a reference unless you can confirm every single change made.
2) if you can confirm every single change made, why are you relying on someone else's tune?
3) the only way to be sure of your map definition is disassembly (yes, there are a ton of broken a2l/damos files out there, do not trust them)
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larppaxyz
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« Reply #3 on: April 27, 2020, 01:21:59 AM »

In my picture, map is defined correctly after all. X and Y axis are defined right above actual timing map, and size matches.

This is how they made it for late 24V VR6 engines. It looks like they optimized it for torque below 70% load and under 3600RPM and variable intake manifold gives it a little twist there. Above that, it's more about power (not torque).

To get going http://www.volkspage.net/technik/ssp/ssp/SSP_246.pdf is very good starting point explaining how VVT works with VR6 engines.

My goal was to make sure that there are no excessive overlapping at high load and high rev areas and there doesn't really seem to be, it's pretty good setup even for low boost. It did a quick test run to test my modifications actually change how timing, by making intake valves open (and close) much later and that had huge negative effect to perfomance. Stock map goes very late near RPM limiter, that must have something to do with engine protection, with my limited experience and googling, it cant be for max power.

Anyway, learning curve here is huge.

Btw. in my case exhaust cam is actually adjustable and not just two positions. Exhaust cam map is pretty much like those with two position cam, but more linear and it's also used when cruising.



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