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Thread: FMIC and stalling

  1. #1
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    FMIC and stalling

    So i set up my front mount intercooler...i forgot the exact dimensions but its big...4 " width and i massaged the inside of the bumper/frame rails with a bfh. With the stock ic no stalling on decceleration. With the new ic it'll stall out on off ramps or sudden redlights..i set up capped off piece of scrap pipe with a gauge and a valve to inflate the system and blocked off the return pipe. it'll hold 18 psi compressed air indefinitely...more than i would ever make...wide band is always hanging around 14.7 at idle wirh either intercooler..sounds like a boost leak but why is it holding pressure?...feels weak sauce with fmic..runs perfect with stock but falls on its face...94 ported with 10% is gonna make heat.

  2. #2
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    Quote Originally Posted by figulaz View Post
    So i set up my front mount intercooler...i forgot the exact dimensions but its big...4 " width and i massaged the inside of the bumper/frame rails with a bfh. With the stock ic no stalling on decceleration. With the new ic it'll stall out on off ramps or sudden redlights..i set up capped off piece of scrap pipe with a gauge and a valve to inflate the system and blocked off the return pipe. it'll hold 18 psi compressed air indefinitely...more than i would ever make...wide band is always hanging around 14.7 at idle wirh either intercooler..sounds like a boost leak but why is it holding pressure?...feels weak sauce with fmic..runs perfect with stock but falls on its face...94 ported with 10% is gonna make heat.
    As you mentioned you might have a vac leak. You can do a smoke test to see where the leak is at. maybe at the intercooler or another connection.
    1994 Supercoupe 5spd Custom, first to buy a 2.1L Big Bore Kenne Bell Twin Screw for an SC
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    1990 35th 5spd 2011 Carlisle 1st place class winner. 12.9@108MPH 1.9
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  3. #3
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    Quote Originally Posted by ricardoa1 View Post
    As you mentioned you might have a vac leak. You can do a smoke test to see where the leak is at. maybe at the intercooler or another connection.
    I read this and thought.....naaah! Can't be. I puffed cigar smoke into vac lines til i was blue..the only place smoke came out was the TB blade/spring thing area which is standard. the system tolds pressurewhen capped off and the stock gauge holds pretty steady at 20 right?? stock boost gauges be lyin' mighty vac reads about 16. I'm gonna shop a proper smoke machine..no more cigars or wasting time trying to bs rig something or building a diy smoke machine. Thanks man. I'll report back when i get this figured out.

  4. #4
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    Quote Originally Posted by figulaz View Post
    I'm gonna shop a proper smoke machine
    I've heard some people rent a fog machine from their local Party City and use it as a 'smoke' source...

  5. #5
    Join Date
    Jan 2008
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    71
    make sure your SC bypass valve is working right.

    with the tubing length required for a FMIC plus the volume of the big'un you put in there you now have an enormous throttled volume.

    on aftermarket supercharged miata's they will actually put a throttle body on the inlet to the SC AND at the intake manifold so that it idles/cruises like stock.
    they play with the linkage between the two TB's so that the one on the intake goes WOT whenever the "primary" throttle pre-sc even cracks open.

  6. #6
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    smoke tester

    I picked one of these up off Fee-bay last year.

    Item # 282390578650.

    Smoke-Tec. Guy out of his garage probably, Harbor freight quality ammo box and hardware. It was less than the $100 listed now. Only used it once so far, but there are a few thing I might redo if I start using it more often. Doesn't produce smoke quite as white/heavy as I hoped, but works. Using cheapest baby oil at Wal-Mart. Was suggested to go to hobby shop and pick up model train smoke oil, guy said it fills up the room when running more than 1 train (not the guy selling them). Seems like it's gonna burn thru wicks fast. All and all, I could probably built a better home made garage unit, but would have spent at least as much, and WAY too much time.

    Adam

  7. #7
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    https://rover.ebay.com/rover/0/0/0?m...2F282687342717
    .
    This what i ordered. It was a little more than the paint cans and ammo boxes. It"s probably the same 2 or 3 guys that have the whole market. I saw 1 for $350 with a built in compressor that was cool..then they jump to $700+. It's probably a glow plug and $40 of harbor freight and home depot stuff but with the regulator, wiring, alligator clips, drilling tapping and adaptors and going back and forth to the shed and home depot and beer....fuggitaboutit.
    i found/repaired a small vac leak but it still shows about 16in Hg.. i again plugged return and pumped compressed air into the inlet and held 20 psi. As far as i can tell the bypass is working. I've seen bigger bypass setups on here but those are usually for like serious twin screw setups. I pulled off the SC to check tightness of return plenum and intake bolts...all good. Bypass hose good. Vac hoses on inlet check out..return plenum large vac line,boost gauge line and fuel reg line all check out. The only dubious thing on my Set up is the 75mm TB. Professional products that seems leaky but that shouldn't impact vacuum. I'll put it back together and see what the smoke machine says.
    Last edited by figulaz; 02-01-2018 at 03:31 AM. Reason: Spelling

  8. #8
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    Not sure exactly what portion of the system you're not checking, but I'd check the couplers that you are un-doing for the pressure test really good. Also, how do you feel the couplers are "fitting"? It's possible to have a vacuum leak where there is no boost leak and vice-versa.
    Matt Haub
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  9. #9
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    Quote Originally Posted by DrFishbone View Post
    Not sure exactly what portion of the system you're not checking, but I'd check the couplers that you are un-doing for the pressure test really good. Also, how do you feel the couplers are "fitting"? It's possible to have a vacuum leak where there is no boost leak and vice-versa.
    Good point! I have a 90 degree coupler and I don't like the way it puckers under vac. I need to take some time and make a few ricer pie cuts and make it right, the couplers fit snug. as far as what im testing i disconnect the tube to the top hat and put the capped scrap piece with the valve and gauge. for the return I use a stock ic tube with the bottom coupling sawzalled off to fit 75mm coupler (here is were i have the 90 degree coupler) i sliced a spare silicone coupler the long way to make a flat piece. i unbolt the return plenum portion of the ic tube and sandwich the flattened coupler between the ic tube and return plenum and sinch it back up. it makes a perfect seal

  10. #10
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    Update

    So i replace the 90 silicone couple with a scrap pc of pipe with a 90 bend and welded 2 inches on and it fits perfect. Still no joy. I hook up the smoke machine and proceed to fumigated my house from the drive way...the unit i bought works really well but bc it's a super coupe it was no match. I put comptessed air into the system and heard it bleed down from behind the intake plenum..after pulling and visual inspection
    Nothing. Pressurized on the bench from the tophat ..built a steel plate and rtv'd at the throttle..sprayed with soapy water .found a tiny pinhole where i ported the smiley a little agressive. I chip of the paint away and its about a 3mm hole...im spot welding with spoolgun and grinding it back. Hopefully this does it.

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