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Fiav

Posted by kingcobb, Apr 20, 2007
Newbie Forum - Beginner DSM modification questions and discussions. Common, repetitive, and general discussions will get dumped here from other tech forums. Unless you're a Probationary member you shouldn't post threads here.

  1. kingcobb

    kingcobb Probationary Member

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    Can someone show me with pics what i've got to block off to get ride of the idle problem please? And maybe show me the difference between the FIAV and ISC...i'm kinda confused now about the two...Thanks LOL
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  2. olmytsi

    olmytsi Proven Member

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    What problem do you have? Idle surge? If so, theres a checklist of things to check before deciding to get rid of the fiav. There´s alot of info on the forums about that already, just type in fiav, isc, or idle in the search button and you´ll be surprised how many threads pop up.
    #2
  3. staticbrainwash

    staticbrainwash Awaiting Email Verification

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    Vfaq is your best friend for this. Look under "intake" there's two big lists of things for you to check before you resign yourself to blocking the fiav.

    If you do end up wanting to block still, jmfab makes a blockoff plate for the fiav.
    #3
  4. Tsi_User

    Tsi_User Proven Member

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    I put up a link in another threat but I'm lazy LOL, it's about half way down

    http://www.dsmtuners.com/forums/showthread.php?t=259194
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  5. brute

    brute Proven Member

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    The FIAV and ISC are both located on the bottom of the throttle body. Here is what the lower portion looks like when removed:

    [​IMG]

    The two middle holes are for coolant to flow through for the FIAV. The lower left hole is also for the FIAV. The top long hole and the bottom right hole are for the ISC. You can block of everything (not recommended) or just block off the FIAV. I wanted to keep my ISC, so instead of just a plate, I machined some holes for air so the ISC would still function. Here's the plate I made:

    [​IMG]

    [​IMG]
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  6. kingcobb

    kingcobb Probationary Member

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    Ok, great thanks alot for the photo's, they really helped. And yea, i've got the idle problem right now, and i wanted to block off the FIAV...so i'll be doing that, but i'm still confused as to what the ISC and FIAV do. And also, Derek (Brute) you said it's not good to block off your FIAV i'm guessing because you do want it to be cooled off on hot summer days, so then why did you block off yours? like whats the big difference really? is it that bad or...? Thanks for your help!

    Chris
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  7. EclipseTrbo420A

    EclipseTrbo420A Proven Member

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    I blocked mine... YOu will notice when you turn the car in it doest idle as HIGH to warm up sits at like 1000 and drops to 700 nicely. I kept my ISC like the plate above and that controls the idle good enough

    THe FIAV has wax inside...when its cold the wax is hard and lets more air through hence higher idle ( to warm up quicker ) on cold starts. Then when the coolant running through the TB and the engine temps get higher, the wax melts and stops air from going through, thus allowing the car to idle lower at normal operating temp ( 700-900 ). Make sence?
    #7
  8. kingcobb

    kingcobb Probationary Member

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    Yep! makes sense now i think, so then the FIAV is the whole piece that sits on the bottom of the throttle body, and the ISC does the actual controlling of the idle speed...When you block off the FIAV, and keeping the ISC, what are you then doing? And if you get ride of the it all together what would happen? What does FIAV stand for btw..?

    Sorry for all the Questions, but i do appreciate the answers!

    Chris
    #8
  9. EclipseTrbo420A

    EclipseTrbo420A Proven Member

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    fial= Fast Idle Air Valve When you block the fiav and keep the ISC you will eliminate a huge passage for air to get through and make your idle really high ALL THE TIME as if it were only when it was warming up See what I mean? I good FIAV us supposed to slowly close and lower the idle to 700 when untill it is fully warmed up. A bad one will just stay open and keep the idle at 1500 or higher and just hold there. So when removing the FIAV and keeping the ISC you are just making the BISS control the idle speed and the ISC regulates it during different tasks like AIR, heat. different driving conditions, stuff like that.

    If you blocked them both, that makes Just the BISS controll idle, and that makes it tricky which is why I opted to go with the ISC as well.

    Hope that helped
    #9
  10. brute

    brute Proven Member

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    Sorry for the late response, I lost this thread. I said blocking everything (ISC and FIAV) was bad. The plates that block everything look like mine minus the holes; they are simply a plate of aluminum. I blocked my FIAV but kept my ISC (hence the holes in mine). Sorry if I confused you.
    #10
  11. NOMIEZVR4

    NOMIEZVR4 Proven Member

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    Hey guys not trying to bring this back but i had a quick question.
    I just want to do the RTV fix for the fiav..Do i put the RTV in the hole which i circled in the picture?

    I plan on keeping my coolant lines going to the TB but want to fix my high idle.

    Thanks for my help

    [​IMG]
    #11
  12. brownfinger

    brownfinger Proven Member

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    Don't do that! Either get the FIAV block-off which retains the ISC, or figure out what's really wrong with your car and fix it. This filling the FIAV with RTV is Kookie-talk! You're scaring me. You probably need a 40cent o-ring on the BISS screw, a $5 TB gasket and a basic tune-up. I'm not trying to be a dick, it just sounds like you're about to make yourself a bigger problem than you know, and it's probably easier to fix it right than you think.
    #12
  13. NOMIEZVR4

    NOMIEZVR4 Proven Member

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    Brownfinger thanks for your input
    I have read in many forums that people have used RTV where the wax is instead of getting a block off plate
    and YES i know that is my issue
    I have already done a BOOST leak test and know for sure that my tb or biss screw o-ring aren't the problems. My ISC is working within specs, i know this because i tested it.

    anyone else?
    #13
  14. PIMking

    PIMking Proven Member

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    Just block it off.

    you will be happier in the long run. Sure it has a hard time holding idle when its cold out but nothing your right foot cant fix. Just make sure your TPS is right unlike mine because it's a PITA while you barley push on the throttle and it jumps high then stalls because you let off the throttle...
    #14
  15. Captainredeyez

    Captainredeyez Proven Member

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    I've been reading this thread and others as well. Maybe I still don't understand or get the picture with blocking off just the FIAV. What would be the benefits to blocking this off.

    Thanks, James
    #15
  16. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    I've been having a problem with my car revving on cold starts but only when it cold outside. Once it warms up it runs and idles fine. I'm going to try the bypass plate. If that doesn't work then I will block it off all together. The sell both bypass and blockoff plates here: Level Zero Motorsports
    #16
  17. dsmfa9nutter

    dsmfa9nutter Proven Member

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    Reving when cold sounds like an isc issue.


    For the last time, THERE IS NO WAX PELLET, THAT IS A MYTH, IT IS A TEMPERATURE SENSITIVE SPRING.
    #17
  18. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    This is my line of thought, it may be wrong but it makes sense to me.

    If it only revs when its cold, and the fiav causes it to idle differently when cold (in order to warm up the engine), then if I bypass the fiav it should idle as if it were warm all the time and therefore not rev when it is cold.

    If the bypass doesn't work then I will get the blockoff plate and be done with the isc too. I've already removed my ac so I don't really need the isc to compensate for accessories.

    I ordered the bypass from level zero, it was $10 shipped. I should have it installed sometime next week, I'll update everyone on the results then.
    #18
  19. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    It worked! I installed the bypass plate yesterday, and this morning when I started it, no engine rev! It idles a little low at first, around 500, but then comes up to normal speed once it warms up. I'm happy!
    #19
  20. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    OK with the bypass the one problem was fixed, no more rev while warming up. But as I stated, now it idles very low when it is cold, around 500. If I drive it before it warms up it idles too low and shuts off. Once it warms up, it idles around 1,000 with no problems.

    Does this sound like a bad isc? Should I block it off completely?
    #20
  21. GaryS

    GaryS Probationary Member

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    I am not an expert, but I am learning.

    I am going through the same things with my car. I suspect both of our cars have bad FIAV's. Replace the TB and see. This is what I plan to do. I also have a bad isc and I am replacing that first, but I suspect my fiav.

    But you should try a few other things, I think. Pinch off the brake booster line to see if idle returns to normal. Also pinch the pcv line, and all the little lines on the tb. Remove the idle switch and remove the throttle cable to make sure the throttle plate closes. If you start it with the idle switch off or disconnected and a bad fiav, I think it will run fast but have no surge.

    Let's not forget a possibly defective egr valve. I think this can cause this as well. I'll replace my isc. If it still surges, I'll check the egr valve, if it still surges, I'll replace the tb.

    I understand the fiav has no wax in it, of course, but how exactly does it work? I wish I looked closer when I had mine off. By the way, if yours is like mine, I recommend against taking it apart as my little gasket did not want to fit back where it belonged. I had to freeze it and hold the gasket in place by dripping water on it and freezing it in place, then quickly assembling it.
    #21
  22. GaryS

    GaryS Probationary Member

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    I am getting closer!

    I got my new ISC and the coil read high at about 40 ohms, but I think that's just fine. I removed the old isc and started the car with nothing in there. It ran like crap, of course, but I stuck my finger in the hole to make sure there was no air passing. The car slowly warmed up and began to surge. I turned the car off. I installed the new isc and plugged it in. I removed the snorkel going into the tb. I took some duct tape and blocked the 2 ports on the tb. I laid the tape so the snorkel holds the tape down when I tighten it. I tightened the snokel bolts. I started the car, and it would barely run until I opened my BISS. Now it idles great!

    This tells me it's the FIAV! I called the yard and got their machine, so I am waiting for the call back.

    I'll let you know how it goes.

    Gary
    #22
  23. GaryS

    GaryS Probationary Member

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    I got the throttle body from the salvage yard for 17$ and put it on. Idle surge is gone.

    The term idle surge is misleading. It should be "fast idle". The only reason it surges is because the idle switch tells the ecu that the car should be at 750 rpm's and it turns off the fuel, then restarts below 750.
    #23
  24. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    I'm glad you got yours fixed. Its always a joy when you get something working right on your dsm. :thumb:
    #24
  25. 91Bomb

    91Bomb Proven Member

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    Little confused here too.

    If I buy a fiav block-off plate ISC still controls idle under varying circumstances but that high 1500 rpm idle at cold start-up will be no more since fiav controls that? So if I block fiav what will my rpm's be on a cold day at start-up? Much lower than 1500?

    Since my fiav is currently good and I'm rebuilding my TB should I just get a gasket and continuing using faiv or get a block-off plate?
    #25

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