Target Boost and Gear Determination Thresholds
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This is a discussion on Target Boost and Gear Determination Thresholds within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; First off if you haven't read my other post i'm working on a 2002 WRX engine and ECU that's been ...

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    Target Boost and Gear Determination Thresholds

    First off if you haven't read my other post i'm working on a 2002 WRX engine and ECU that's been put into a '59 Porsche Replica NOW another couple of questions

    1: Since i didn't see it in the ROM i downloaded off the ECU, but heard Subarus limit boost in 1st and 2nd gears isa that true for the 2002 WRX? (ECU is set up as a Manual trans ecu right now too)

    2: Gear Determination Threshold, the engine is now bolted to a 4 speed tranmission, how can one alter this section for for a four speed?

    thank you once again for any help
    Kevin

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    Registered User Heide264's Avatar
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    I'm not so sure about the finer details of the older ECUs. The newer drive by wire cars do 'limit boost' per gear, but it is done via target boost reduction and wastegate limitations by capping requested torque.

    I'd recommend checking out the RomRaider forum if you haven't yet. They'll be a bit more versed in stuff like that. We do have a few members here that may have some advice for you though.

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    Moderator Donkey's Avatar
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    The 16 bit ECU's do not limit boost persay,but they are tuned for 5th gear. Most people tune for 3rd gear boost when they remap the ECU.
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    I am register on the romraider site but I honestly don't even have a clue as to where to post this type of question. Also I couldn't get their software to work either. Sadly I don't have the time to play with it

    Also it's nice it doesn't limit boost per gear. Now I guess the gear determination part isn't that necessary either

    Thank you all again.

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    Registered User Alexmartynyuk's Avatar
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    Quote Originally Posted by 91 XR7 View Post
    First off if you haven't read my other post i'm working on a 2002 WRX engine and ECU that's been put into a '59 Porsche Replica NOW another couple of questions

    1: Since i didn't see it in the ROM i downloaded off the ECU, but heard Subarus limit boost in 1st and 2nd gears isa that true for the 2002 WRX? (ECU is set up as a Manual trans ecu right now too)

    2: Gear Determination Threshold, the engine is now bolted to a 4 speed tranmission, how can one alter this section for for a four speed?

    thank you once again for any help
    Kevin
    the 2002 ecu doesn't have that function, I don't know why someone would want to limit boost in first and second on a wrx because we don't have traction issues. Those tables are meant to help have a flat boost peak in all gears but you could alter it to limit boost but not on an 02 ecu. I'm assuming you are trying to limit boost because of traction issues since this is not in a wrx?

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    Subaru Newb MainFrame's Avatar
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    Quote Originally Posted by Alexmartynyuk View Post
    I don't know why someone would want to limit boost in first and second on a wrx because we don't have traction issues.

    Because we don't have traction issues, so you see people breaking transmissions left and right?



    Even though the ROM doesn't have per gear boost thresholds (or whatever you want to call it), boost is still load dependent, so you will still see lower boost in lower gears because they don't load up the engine as much.

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    Quote Originally Posted by Alexmartynyuk View Post
    I'm assuming you are trying to limit boost because of traction issues since this is not in a wrx?
    Quote Originally Posted by MainFrame View Post
    Because we don't have traction issues, so you see people breaking transmissions left and right?
    boost is still load dependent, so you will still see lower boost in lower gears because they don't load up the engine as much.
    Traction doesn't seem to be an issue, Rear engine Rear Drive and semi sticky tires and a engine that seems to come alive at @ 4,000 rpms, So basically it wasn't really to limit the boost persay, other then maybe in just first gear, but rid of the limiting

    the tranny is only a 4 speed, 3.78 1st, 2.06 2nd, 1.26 3rd, 0.93 4th with a final drive of 3.44. So i think gear ratios are close to the first 4 gears in WRX except for a longer final drive (good for loading the engine and getting the turbo to spool, might be why the car is more fun on the freeway?)

    thanks

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    Subaru Newb MainFrame's Avatar
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    Ditching all the drive-train loss associated with AWD will also make it more fun on the freeway.

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    Registered User Alexmartynyuk's Avatar
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    if you are looking to get the same boost in all gears there is another way to do it with an 02 ecu, I use a hybrid boost control method, I use a grimmpseed 3 port ebcs and a hallman pro rx mbc in parallel. All I can say is that I get 21psi in ALL gears, if that is what you are trying to achieve then pm me and ill tell you more.

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