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Title: Boost control m3.8 Post by: kacperoooni on January 14, 2020, 11:38:56 AM Hi,
Been reading about m3.8 used in older 1.8t engines for example. I'm trying to figure out how boost control in this thing works. Many people is just saying about KFLDS and factor 10.24 for pressure for stage 1 files. Some time ago I've found another map which is called LDSMXN and its 2d map similliar to LDRXN. The LDSMXN map has max values about 6.5ms which is about 0.3/0.4bar pressure. Last 3 rows in KFLDS are above values in LDSMXN and with 10.24 factor are about 0.5-0.6 bar which is correct stock pressure for this engine. So what is LDSMXN used for? Title: Re: Boost control m3.8 Post by: prj on January 14, 2020, 03:07:52 PM There is no factor for pressure, who came up with that bullshit?
M3.8 has no concept of pressure whatsoever, everything is done based on MAF. Title: Re: Boost control m3.8 Post by: kacperoooni on January 14, 2020, 03:33:50 PM There is no factor for pressure, who came up with that bullshit? Yes, it's simplification. The last row i about 7.5 ms load and its what ecu demand. So what is LDSMXN for? M3.8 has no concept of pressure whatsoever, everything is done based on MAF. I have another question too. How motronic is still able to control pressure if maf is damaged and measures less airflow than it should(but enough not to put ecu in limp mode)? In group 025 I can see requested load, corrected and actual load. When it measures less airflow than it should ofc actual load will be lower, but why the PID doesnt try to reach specified load? Where this correction comes from? Title: Re: Boost control m3.8 Post by: prj on January 15, 2020, 02:05:08 AM The PID will always try to reach the specified load.
If your WGDC is maxed then of course it's done. Also, the target is the corrected load. KFLDS is target, LDSMXN an additional max limiter. On a stock car, it's better to fit a 4 bar FPR otherwise you will run out of injectors before you run out of turbo. |