Need to adjust Idle on FRPP 70mm T/B!!! (ASAP)

Discussion in 'SN95 4.6L Mustang Tech' started by BlackenedSVT, Mar 11, 2006.


  1. Mike97gt

    Mike97gt it doe snot Mod Dude Founding Member

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    Yeah I saw that drilling on the TPS and somebody wanted him to drill a hole in the TB :nonono:

    the IAC could be stuck partially open, that would cause the overspeed error. thats why I am telling him to tap it witha hammer that might unstick it.

    I now think his problem could be IAC related.
  2. BlackenedSVT

    BlackenedSVT Active Member

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    Ok so i brought my car into my tech school today to examine it. To make a long story short here is what happened:

    - I pull in and the Service Engine/MIL is on. I run it through a more advanced scanner than the old snapon one i have at my work, and it gives me 2 codes:
    CODE 1 : P1000 - OBD II Monitor Test/Drive Cycle Not Complete
    CODE 2: P1506 - IAC Overspeed Error

    So clearly there is to much air through the IAC or something there abouts, which is causing the high idle. Next we....

    - Spray some PB blaster/carb cleaner over vacuum lines, intake/TB connections to the manifold, over gaskets, etc....there was NO vacuum suckage....

    - Then a few of us take turns trying to put our hand over the T/B (MAF disconnected) with the car running, to see if the car will die. When we found a kid with a big enough hand, and could position it under/over my strut tower brace, he was able to kill the engine. So that lead us to believe there was no vacuum leak.

    - Ok so we take the ENTIRE T/B and plenum off, and put the stock one back on...this is stricly to see if the problem was with the ported plenum, T/B or the IAC.... with the stock plenum and t/b back ON, the car runs nice and smooth again at 900rpm idle w/ no hanging RPM. this is how my car is now, running fine with the stock plenum and t/b on

    - Upon further inspection of the PORTED plenum and FRPP 70mm T/B my instructor and I notice the problem!!!! The FRPP 70mm T/B has a small 1/4 (about) size hole right through the t/b blade. The same hole that guy on page 3 of this thread told me to put in the blade, and the same hole that you guys said not to put in the blade!!! It looks factory though, like the FRPP t/b was supposed to have that hole there or something. ANOTHER problem was that we could get our fingertips to just grap the top of the t/b blade with the t/b in the fully closed position. We could just knick it...something we could not do on the stock one.

    In conclusion, i would have to assume that this 1/4 hole through the throttle body blade is the problem with the high idle, becasue now the IAC AND the hole are putting air through the intake....


    SVT TECH unfortunately things were hecktic today, and i was not able to get you the fuel trims with the ported intake on, but here is some other random info i pulled with the 70mm t/b and ported intake on the car, with the engine on and the scanner hooked up:
    - Idle Air Control: 32.8% (idleing, engine on)
    - IAT: 2.81v
    - Baro Pressure 15.00 psi
    I'm sure none of the above really is important, except for maybe the IAC showing 32% at idle.

    I WILL BE POSTING PICS SOON OF THE PORTED PLENUM AND 70mm T/B NOW THAT IT IS OFF THE CAR. MAYBE YOU CAN HELP ME NOW. :)
  3. Mike97gt

    Mike97gt it doe snot Mod Dude Founding Member

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    OK that hole would cause the idle to hang high like that. of course the computer can not control idle with the hole there.

    patch up the hole with somthing that will not fly off and enter your engine and see if the hanging idle is fixed with the ported TB/PLENUM
  4. BlackenedSVT

    BlackenedSVT Active Member

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    HERE ARE SOME PICS FOR YOU GUYS (TO GO WITH MY PREVIOUS POST):



    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
    Here you can see the air gaps around the T/B Blade. They aren't terribly big, but there...I have them illuminated with a light behind the blade, so thats why they look wider than they probably are...



    What did you guys think of my porting job?? :)
  5. BlackenedSVT

    BlackenedSVT Active Member

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    Any recommendations on what i should use to patch that up??? JB weld maybe? :shrug: I'm not quite sure what to use.... hmm....
  6. jstreet0204

    jstreet0204 Active Member

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    First are your sure the hole was as big a 1/4. I have the same frpp 70mm throttle body. I went out and check mine, and it does have a SMALL hole in the blade. Less than an 1/8th inch. I've attached a photo, you can see it right where a the smudge is.

    Second, are you changing you IAC valve between the two plenums, or did it come with one on it. If it did, the one on it is probably bad.

    Edit : I see you posted your own pics while I was checking mine. That hole is normal.

    [​IMG]
  7. Mike97gt

    Mike97gt it doe snot Mod Dude Founding Member

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    Those gaps look pretty big to me. I think that T/B is junk.
  8. BlackenedSVT

    BlackenedSVT Active Member

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    No im not sure of the EXACT size of the hole in the t/b blade.

    No didn't change the IAC valve, its the same valve that is on the car, just plugging in and unplugging as i need to, to change t/bs....




    SVT TECH I know this is kind of a "no no", but if those gaps are excessive...can i just back off the t/b set screw? My tech school instructor recommended that i take that T/B set/positioning screw completely out, and replacing it with a screw that has a hex or allen key end, so i can adjust it as need be.

    What do you think of that idea? If i adjust it, i can have it closed all the way, and then plug up that hole in the blade. :shrug:
  9. jstreet0204

    jstreet0204 Active Member

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    For reference, it looks like mine closes all the way. The previous owner may have adjusted yours out some which is what I was getting at in my original post. If that stop is not letting it close all the way, that is likely why your tps voltage was high to begin with. I edited the post you quoted after I saw your pics. That hole is factory.
  10. BlackenedSVT

    BlackenedSVT Active Member

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    TPS voltage is .98v at idle.....even with those gaps
  11. jstreet0204

    jstreet0204 Active Member

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    Yeah, but that is after you messed with it quite a bit, wasn't it?
  12. Mike97gt

    Mike97gt it doe snot Mod Dude Founding Member

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    one problem I see is the hole and gaps combined. it looks to me like you tried to port the T/B and the problem with that is so much material was removed now the T/B blades have gaps. now you have 2 options

    1. plug the hole even with it being factory, the purpose of the hole is to allow a little bit of air to enter the manifold with the blade closed. this allows for smoother c/t to p/t or wot operation. all throttle bodies have a hole like that.

    BUT with the amount of material you removed you increased the amount of air that is entering the intake with the throttle blade closed. that will cause the idle to stick high. and if you close the hole that will leave just the gaps to allow air in and see if the idle is better then.

    2. toss the T/B and get a new one.

    also we need to know if you have two different IAC's
  13. Shiroelex

    Shiroelex There's nothing worse than aut Founding Member

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    First page, man!
  14. Mike97gt

    Mike97gt it doe snot Mod Dude Founding Member

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    congrats!!! I think you were right
  15. BlackenedSVT

    BlackenedSVT Active Member

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    I never ported the T/B. I did not touch the throttle body at all, i mearly put it on the plenum with a custom gasket i made for it. The T/B was given to me by someone else. He bought the t/b and had La Rocca's Performance here in south jersey install it.

    I can't toss the t/b and get a new one because i have no money, i'd prefer and WILL find a way to make this one work.... In your #1 Suggestion, are you suggesting i LEAVE the t/b set-screw alone, and just plug the hole in the blade? So this way there is still air going over the gaps in the blade...

    ...because i think i should mess with the set-screw to close the blad fully, THEN plug the hole in the blade, so everything fits tight again. My stock 65mm t/b does not have a hole through the t/b blade.
  16. Mike97gt

    Mike97gt it doe snot Mod Dude Founding Member

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    try pluging the hole and see if it runs better. it probally will.
  17. Dan02gt

    Dan02gt Member

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    I've seen alot of stock, un-modified TBs with that hole. Your throttle stop screw has deffinetly been moved turn it back in so that the blade closes all the way but not so much as that the throttle sticks. After this is done you will need to readjust your TPS.

    Your engine will run if you cover the TB, the IAC will keep it supplied with air.
  18. BlackenedSVT

    BlackenedSVT Active Member

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    Ok well im going to work at my shop today, i'll be bringint the ported plenum and installing it .....again (after i plug up the hole and adjust the set-screw). I will be getting back to you guys later.
  19. Shiroelex

    Shiroelex There's nothing worse than aut Founding Member

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    Don't do both! It'll probably stall then. Just adjust the set screw while the TB is in your hands, to where the blades just seal the hole up. I'd do that first, since that's how it's supposed to be. If it still idles high after that, hen look into sealing the hole, which did actually look a tad big to me.
  20. BlackenedSVT

    BlackenedSVT Active Member

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    Ok well i already did both. I just "JB Welded" the small whole in the t/b blade, and i adjusted the set-screw so the T/B was fully closed and almost sticking, then backed it off a little. It is very easy to adjust if i need to later.

    Sooo I will be letting the JB weld dry overnight, and then i will install the ported plenum...again....

    Should the car stall, i can easily take off the JB weld AND/OR back the set-screw off. I just hope i can get this thing on and running smooth tomorrow, because if i can't, it woudl leave me to believe something ELSE was the problem.....All signs point to this T/B though

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