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1G FIAV bypass

Posted by Adrian97, Jul 9, 2019

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  1. Adrian97

    Adrian97 Proven Member

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    Göteborg, Europe
    Hello
    I want to BYPASS my FIAV, no Block Off. I have a 90 TB, I know that i can close FIAV using free mod like here . So if i want to BYPASS my fiav I have to do it like on video ? I have to use a bypass plate also ?
     
  2. Cherry

    Cherry Proven Member

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    Hull, Georgia
    What do you mean by bypass? As far as I know there is no bypass, you either leave it be and it works like it should unless it goes bad, or you close it like in the video or block it off with a blockoff plate.

    Is there a reason why you want to close it off?
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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  3. Vegas smith

    Vegas smith Proven Member

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    Houston, Texas
    You either use a bypass plate or you close fiav by screwing it in all the way. Unhook the coolant lines in both cases.
     

    Street Build 3K  10

    1993 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  4. Adrian97

    Adrian97 Proven Member

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    Göteborg, Europe
    so close FIAV like on the video = block off ? I can do it like on video or buy a block off plate and install it ?
    when i want to just by pass FIAV , I do not have to close it ? just buy By pass plate ? I want to use IAC so i dont want to BLOCK OFF FIAV
     
  5. donniekak

    donniekak DSM Wiseman

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    Surprise, Arizona
    If you screw the fiav in all the was the iac still works.
     

    Street Build 3K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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  6. TeamFury

    TeamFury Proven Member

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    Raeford, North Carolina
    Just be sure to spray some pb blaster/wd-40 when you screw it in. Almost the ones I did had a lot of crap built up.
     

    Drag Race Build 4K  1

    1991 Mitsubishi Eclipse GSX
    9.98 @ 138 · 1G DSM
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  7. Cherry

    Cherry Proven Member

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    Hull, Georgia
    I dont know why people call them bypass plates when its a block off plate. There are 2 things in the housing and it would seem the 90 is easier according to this thread https://www.dsmtuners.com/threads/free-fiav-block.391977/. The "bypass" plate blocks off the FIAV while the block off plate is technically a FIAV housing block off plate.

    Technically you arent bypassing anything unless people think that air going through the ICS is a bypass for the FIAV somehow. Though even the bypass plate says that it blocks off the FIAV.

    Thats why I asked what was meant by bypass since the only thing you can do is block off that air channel. It can be confusing when someone is using bypass to actually mean bypass and another person is using bypass to mean block off which just isnt correct.
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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  8. Adrian97

    Adrian97 Proven Member

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    OK I understand, I need BLOCK OFF plate only when I want tottaly block the FIAV. I will only " BYPASS " FIAV so i does not need any plate. RIGHT ?
    Just screw it in and unhook the coolant lines ?
     
  9. Cherry

    Cherry Proven Member

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    It looks like you cant even get a plate for the 90 throttle body since it is a solid piece design where the throttle body and FIAV housing is one piece. You basically remove 5 screws total, 2 are holding on a sensor connector and 3 more screws for the adjustment cover. Turn the adjustment clockwise until it no longer turns and then put the adjustment cover back on, the sensor connector mount and reinstall your throttle body.

    The guide I linked shows pictures and walks you through it.

    Is there any reason why you want to close it off?
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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  10. Adrian97

    Adrian97 Proven Member

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    Thanks :)
    Not yet , but who knows...

    I dont understand why they sold these plates when you can do it without these
     
  11. Cherry

    Cherry Proven Member

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    The plates are for the later versions so you dont have to pop out the freeze plug to gain access to the adjustment. The FIAV housing is separate from the throttle body for I think 91-94 at the very least since I dont know much about the 2g engine. You basically take off the housing by removing 5 screws and put the plate in between the throttle body and FIAV housing. It either blocks off the entire thing or just the FIAV air channel.

    For a daily driver blocking off either the FIAV or ICS absolutely sucks in terms of convenience since you have to be there to warm the car up and it sucks even more in the winter. I had the whole thing blocked off and it just sucks. Ive been spending time and money fixing my idle issue so i dont have to mess around if i want to go anywhere. I have a motorcycle though so theres that.
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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  12. Adrian97

    Adrian97 Proven Member

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    you blocked completely FIAV or only FIAV air channel ?
    I thought that blocking only air channel " bypass" so that ISC is still work, its harmless.
     
  13. Cherry

    Cherry Proven Member

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    I blocked off the entire thing. Blocking off the FIAV air passage is harmless other than you become the FIAV until the car warms up.

    I just had a lot of idle issues so to be able to use it I blocked off the entire thing, now that its warm out I can work on my car and ride my motorcycle until things are sorted. And its getting expensive.
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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  14. Dsm panda

    Dsm panda Proven Member

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    If you block it you may have issues idling while cold i had to hold the throttle open to keep running. just buy the bypass plate. There are two plates block off and bypass. The bypass plates have a opening to allow the isc to work on regulating air flow and will only block the part that is with coolant and the wax ball. I swapped my block off one for a bypass and it made a world of difference you dont want to block the isc off or it wont idle as smooth at low rpm I had to adjust my biss to let me idle at 1k with block off with the bypass I idle at 750.
     

    959  2

    1991 Eagle Talon TSi
    327 whp · 307 lb/ft · 1G DSM

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    1990 Plymouth Laser RS Turbo
    fwd · manual · 1G DSM
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  15. Cherry

    Cherry Proven Member

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    Yes, if you block the FIAV passage you have to become the new FIAV on cold starts. And the 90 tb from what it looks like cannot get the plates since it' a single unit.

    I really don' like the term bypass because you aren't bypassing the FIAV but actually blocking it off while keeping the ICS.
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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  16. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    I screwed mine all the way in and adjusted the "Coolant Offset" in Link and my car starts and runs like I never closed it off.
     

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    1967 Chevrolet Camaro RS
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  17. Vegas smith

    Vegas smith Proven Member

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    How did you determine the bets way to adjust that setting?
     

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  18. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    I just had to sit in the car with the computer and play with the settings, so that when it was cold, it would run richer. It has been a while since I had to do that, but I always just sit in the car and let her tell me if she likes my changes or not. I wish I could be more informative, but I don't have a log to look at to see my settings at the moment.
     

    277  17

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

    Street Build 394  4

    1998 Eagle Talon TSi
    fwd · manual · 2G DSM

    Street Build 3K  21

    1992 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

    Street Build 5K  11  25

    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM

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    1990 Eagle Talon TSi AWD
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    Vegas smith likes this.
  19. Cherry

    Cherry Proven Member

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    It sounds like the same thing people do with the RB26. Though their system is a little more complex. You remove the throttle bodies and the FIAV system put on a new intake manifold and throttle body and the computer takes care of cold starts.

    You just have to have the stuff and knowledge to do it.
     

    Street Build 181  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
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