IAC restrictor plate installed!

Discussion in '1994 - 1995 Specific Tech' started by R.J., Dec 31, 2005.


  1. Guero

    Guero Active Member

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    Plates

    nevermaind
  2. R.J.

    R.J. Member

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    Sorry I don't have any left. There are people selling them on ebay for like $15. Just do a search for "restrictor plate". It is totally worth the money.
  3. Starman

    Starman New Member

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    I slotted the top of the stop screw with a dremel and small cut off wheel so I can use a small standard screwdriver to adjust it.

    As far as these restrictor plates....they appear to help, but doesn't the recessed allen head set screw right in front of the IAC on the throttle body do the same thing?? That screw is V shaped and blocks the passage when closed
  4. R.J.

    R.J. Member

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    You can not get the same idle quaility and range of adjustment with only the screw. Basically if you set your idle right now then installed the plate, your idle would change and you would have to readjust the screw. This means the screw would be in a diff spot to get the same idle speed with less hanging idle and better between shift performance.
  5. Swarzkopf

    Swarzkopf Member

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    A little late on this...but mine is installed and works GREAT! Much better idle quality, no more hanging, and perhaps it's me but the car feels more responsive.

    Two thumbs up on this one.
  6. R.J.

    R.J. Member

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    I think the throttle responce between shifts is the best thing about these plates. It took the plate and a set screw adjustment to fix my idle. I am glad you like the results and it worked that well for you.
  7. SFStang

    SFStang New Member

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    iac restrictor plate


    HI RJ,

    Do you have any more plates made? I'm having the same idle surge and would like have one of these installed. If not where can I buy one. Thanks in advance.

    -Lester,
  8. 1slow95

    1slow95 Founding Member

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  9. 18mustangs

    18mustangs New Member

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    I just installed this plate on Sunday with my Fox TB conversion and it works great! There is noticeable throttle response improvement, noticeable SOTP improvement. The car also has better manners at low throttle than it did before. However I didn't have a hanging idle before, and still really don't but it does hang longer than it did without the plate, but that could be because I had to set my base idle a bit higher than without it. Overall, it was a great mod and I'm very happy with it.
  10. R.J.

    R.J. Member

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    The plate was designed originally for the Mach 1 and it's hanging idle problem. The best thing that I gained from it was the throttle responce. More so throttle responce between shifts!! My exhaust sound changed and my idle got a little better. Over all on Stangnet, I think one person got zero results from installing the plate. Now that I did my H/C/I and SCT tune, the plate is not needed for throttle responce. The chip takes care of that very well.
  11. 18mustangs

    18mustangs New Member

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    RJ, first thanks for a quality product, it was very well made. I also noticed a slight change in my exhaust note but thought I might be imagining it. My idle isn't hanging with the plate noticeably anymore, perhaps my car's learned the idle. I too noticed the improved response between shifts in addition to the low throttle responsiveness.

    Bottom line, the car is even more fun to drive.
    Tim
  12. 1slow95

    1slow95 Founding Member

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    I had my idle set waaaay off when I had my car tuned, and it started surging a month or so later. I reset the idle and it idled at 1200 and hung around 1800 forever, so I sent the chip back to my tuner and had him make some adjustments. It idles great now, but it still hangs around 1500. For $14 this plate is worth a shot before I take the car back for a re-tune.
  13. R.J.

    R.J. Member

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    Have you tried setting your idle with the procedure below:

    Begin with a cold vehicle. The idea here is to get the car to a firm cold idle with enough air bleed capacity left in the idle circuit for IAC adjustment.

    The idle stop should be set first. Back out the idle stop screw, away from the bell crank arm, until about 1/2 turn past the point where it no longer makes contact (blade fully closed). Using a 0.010" feeler gauge, tighten until gauge just drags between screw and bell crank arm. Remove feeler gauge. Tighten screw exactly 1 1/2 turns. If the screw is very loose, put a drop of loc-tite or silicone on it, so it doesn't work out of adjustment.

    Now remove the connector to the Idle Air Controller (IAC) just on the other side of the throttle body. Start the car and allow vehicle to warm for 2 minutes. Give a small "blip" to let it settle. If it is having a hard time staying running you may have to get an assistant until you can get to the front of the car. Now open or close the air bleed screw (CCW opens) next to the IAC until the car idles at 575 to 600 rpm. For guys with aftermarket cams and an EEC tuner, you might want to idle a bit more briskly, say 650 to 675.

    Obviously, this rpm range is by what the car and driver wants...IE, no set idle speed, whatever works for YOU.

    Turn off the car. Now count the number of turns clockwise to close on the idle air bleed screw. If it falls between 1/2 and 2, it's okay, now reverse it out the same number of turns. Log the number somewhere in case you need it for the future. Reconnect the IAC. You are done.

    If the air bleed screw is above 2 turns, it's a good idea to tighten the idle stop screw another 1/2 turn, and then repeat the idle setting. If it is below 1/2 turn, then loosen the idle stop screw by 1/4 to 1/2 a turn, and repeat the idle setting. Be sure to put another drop of silicone RTV on the stop screw if it was disturbed. Reconnect the IAC. You are done.

    Just this procedure can fix all your idle problems but this with a plate is perfect. I used the plate before my H/C/I and tune. After the tune all I use is this procedure. Just watch your TPS voltage as you make adjustments.
  14. 1slow95

    1slow95 Founding Member

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    I followed those directions the best I could since I have a fox tb. One thing I forgot to do was check the TPS voltage, so that could be a problem(probably not tho). It runs great on the stock tune, so I know the idle is set right.

    I had Brian burn the chip and mail it to me before I took the car to him for a dyno tune. When I installed it, my idle went from around 800 to 1300, so I turned the throttle stop screw until it idled right, which just happened to be with the throttle all the way closed. I forgot about that when the car was tuned, so it was never fixed. I also set the TPS after that to .91V, so it could be over 1V now that the idle is set right.
  15. R.J.

    R.J. Member

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    My chip is a custom tune so I can't really compare it to yours but I learned something about chips and idle rpms when I had mine done. My tuner turned my idle screw all the way down and used the chip to make the car idle at what ever he wants. If you have a pre burned SCT chip, were you asked what idle rpm you were looking for? Maybe your chip is set for one rpm and the iac is fighting it. My car uses the gap at the throttle plate (set screw) and the computer (chip) to idle.
    Try getting maybe 1.5-2.0 turns past .010 gap on the set screw and .9 TPS voltage then turn your idle screw all the way down.
  16. 1slow95

    1slow95 Founding Member

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    I think I've got you pretty confused :) I have a custom tune, but I bought the chip with a tune before I had it on the dyno. This first tune threw my idle off, and I forgot to do anything about it when I had the car dyno tuned.

    I think the computer was set to control the idle like you said. I don't really like that because my throttle sticks when it's closed all the way, plus the car would surge and die when it was hot. I mailed my chip out and had it reburned, then my idle was great but it would hang at 1600+.

    I bid on that plate on ebay, but it's up over $20 now so I said ef that and made my own plate tonight. I just drove it down the street and back and I can tell it's muuuch better now. It's still hanging, but it's down to around 1200 rpm.

    Im assuming the small hole in the plate goes on the side towards the air intake, not the side going into the engine?
  17. R.J.

    R.J. Member

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    I am glad it is working for you, how is your throttle responce between shifts?
  18. 1slow95

    1slow95 Founding Member

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    Throttle response was good before I installed the restrictor plate, it may be a little better now but I havn't really noticed.

    Since I've drove the car some more I think the computer learned about the plate because my hanging idle is back up to 1500 rpms most of the time. I guess I'll just have to live with it like this until I can make it back to columbus for a re-tune. At least it's a little bit better. :)

    I also have not reset the computer since I installed the plate, so I may give that a try sometime soon.
  19. R.J.

    R.J. Member

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    There is a learning curve for the computer. I installed a plate on a friends 04 Mach 1 and it would not idle good at all untill we unhooked the battery for a while.
  20. Road_Runna

    Road_Runna Member

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    Any new replies? It's been 8 months.

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