Tips for mapping hybrid turbo

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Tips for mapping hybrid turbo

Postby sergiu_w32 » Fri Mar 31, 2017 10:50 am

Hello,
I need some tips/help in order to correctly map my hybrid turbo.

My setup is:
BMW 320d E46 2002 (150hp stock)
+ EGR off (only software)
+ Big FMIC
+ Straight pipe exhaust (decat)
+ Hybrid turbo GTX1756

I've been running this setup (except the hybrid turbo for a few years without any problem), and now I decided upgrade to a hybrid turbo.
I'm trying to adjust the VNT maps, and I have a weird issue. The car pulls pretty well after writing the file, but the day after it does not
pull anymore in first gears, the turbo kicks in late @3500 rpm, and it does not kick in all the time in first gears (perhaps there are some adaptations) ..

My ECU is EDC16C31 (SW 361858), and there are 2 sets of VNT maps (4 maps):
- 1 (F7F44) -> VGT lift Map
- 2 (F8478) -> Base Control value
- 3 (F86BC) -> Base Control value
- 4 (F8900) -> VGT lift Map

And there seems to be a limiter/max value map after the requested boost maps (but I did not change this one):
- (FA3DC) -> VGT max value

Are there any other maps that I should consider ? Limiters for N75 / VNT that I am missing ?
I am attaching the orig ECU file for reference.
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Re: Tips for mapping hybrid turbo

Postby sergiu_w32 » Fri Mar 31, 2017 1:53 pm

This is the best version I've managed to do so far (playing with the N75 values); Log done in gear 2,3 and 4:
- 2.9 bar requested max in the maps
- ~ 90 - 95 mg of fuel injected per stroke
- lambda 1.173 (AFR 17)
- 1800 bar Rail Pressure


The problems with it :
- overboost when turbo kicks in @3000 -3500 rpm
- in gear 1 and 2 turbo kicks in even late
- after one or 2 day (perhaps after adaptations), turbo does not kicks in even late in first and second gears @3500 - 4000 rpm
and sometimes it does not pull at all in first 2 gears
- in gear 3 there is lag between 2000 and 3000 rpm (after adaptations)
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Re: Tips for mapping hybrid turbo

Postby sergiu_w32 » Fri Mar 31, 2017 3:05 pm

Forgot to mention the legend of the log graph:
- dark green -. Engine Speed (rpm)
- pink -> actual boost
- light blue -> requested boost

Is it the PID Control that I'm messing with ? What else could it be ?

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Re: Tips for mapping hybrid turbo

Postby sergiu_w32 » Tue Apr 04, 2017 12:45 pm

Got it sorted, with help from a more experienced person (many thanks to Martin for making things easy/clear)

For those having similar issues, I'll write a summary of the solution:
- Generally a hybrid turbo should work fine with no modifications to the turbo vanes position (VGT),
but the boost request/set point maps should be adjusted to match with the actual boost generated by the new turbo,
since the air flow is now different (less boost is required to generate the same air flow)
- This often means lowering boost with a hybrid

So as plan, I've followed the next steps:
- Lower boost request maps, by matching them with actual boost (after road logging),
so that the engine is happy with them (PID control intervention is reduced to minimum)
- Adjust Lambda / Smoke maps to mirror the new boost request
- Slightly adjust the turbo vanes (VGT) maps, ONLY if you can't get boost under control

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Re: Tips for mapping hybrid turbo

Postby sergiu_w32 » Wed Apr 05, 2017 1:35 pm

Here is a graph in gear 4 from 1950 to 4000 rpm:
- boost 2.85 bar
- IQ 94 - 98 mg

Legend:
- dark green -. Engine Speed (rpm)
- pink -> actual boost
- light blue -> requested boost
- red / green -> IQ
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Re: Tips for mapping hybrid turbo

Postby martinlink » Thu Apr 20, 2017 10:54 pm

I'm having similar issues with my refurbished turbo on exactly the same car (also sw 361858, same mods apart from hybrid).
The turbo's vane gap is set pretty tight so it starts to boost as early as possible. This is probably making the PID pretty active and I've tried messing with the PID maps but they have little effect...

I might have to try the same solution (reducing requested boost) to calm down the PID controller.
Maybe you have some input on my topic as well? Any ideas? :angel:

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