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Thread: Throttle body butterfly valve plate is stuck in closed position

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    Throttle body butterfly valve plate is stuck in closed position

    I removed my throttle body to port match it to the rubber insulator and the intake manifold. I sprayed carb cleaner and some break cleaner into the throttle body to wash out the sanding residue.
    After doing this, the butterfly valve is stuck closed!
    I took it to an automotive machine shop and they could not figure out why it's not opening.

    Does anyone know what could be causing the butterfly valve to be stuck shut and what I can do to get it working?
    Is it possible that the cruise control motor assembly is the problem?

    Any help is greatly appreciated.
    Last edited by stevenlee; 11-15-2009 at 01:38.

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    Charter Champion Larry Bastanza's Avatar
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    Re: Throttle body butterfly valve plate is stuck in closed position

    Hi Steven,

    I forgot, is you car a TBW throttle?

    Sounds like it is, and the throttle motor has some issue. The thing I am trying to understand is what changed. I assume it was working when it was removed, no??

    Regards,
    LarryB

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Larry, my car is a '94 with a throttle cable. It was working smoothly until I sprayed the carb and break cleaner to remove the sanding debris that accumulated on the inside and outside of the throttle body assembly. I am also suspecting a throttle motor, if there is one for cruise control or the throttle position sensor. The valve is frozen solid, with no movement at all.

    P.S. I removed the intake manifold so that I could remove the alternator bracket and re-tap it for larger motor mount bolts as you previously suggested. That worked out fine.

    While I had the intake manifold off, I decided to do some mods to reduce the plenum volume (for faster spooling of the turbos) so I remove the VVIS plate that had already been gutted. I also removed the center rib in the intake manifold and polished the entire intake manifold and match ported the intake to the rubber throttle body insulator to improve the air flow. I also decided to remove the EGR components and trying to figure what all can be removed. (I have not been able to find the EGR section in the manual.)

    Now I'm wondering if I should have my throttle body enlarged (big bore- 5mm larger) and match the bore of the intake manifold and the rubber insulator to the larger TB while I have everything off. My TB has a welded intake flange that measures 75mm for the Wiggens clamp that connects it to the charge pipe that comes from the intercooler. The stock throttle body has a 65mm bore.
    Do you know if a larger bore throttle body would produce any gains...and if it would have and detrimental effects, i.e. fuel economy or more difficult throttle modulation?

    Thanks a million for your help!



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    Last edited by stevenlee; 11-15-2009 at 10:55.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Brian,
    There is no movement at all. I just revised my previous response to Larry and provided additional details.

    Thanks for your interest!

    Steve

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    Re: Throttle body butterfly valve plate is stuck in closed position

    I would say the brake clean or carb cleaner reacted with the shaft and the body frezzing the shaft in place. You may what to try a little pb blaster in the shaft where it goes into the body and see if it can loosen it up.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Brian,
    Thanks for the recommendation.
    I took the throttle body to an automotive machine shop to see if they could figure out a mechanical reason for the problem. They put some kind of "light oil" and it did not free up the valve. I don't have any PB Blaster but I will try liquid wrench on the shaft.
    I am wondering if the throttle position sensor could be frozen.... or maybe it's the motor that closes the throttle when cruise control is activated.
    I don't want to unnecessarily remove any of those components because I'm concerned that they may not be calibrated the same after they are replaced.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    That motor is not for the cruise control. It is for the TCS. Try removing the motor and see if it frees up the throttle plate. I got rid of that motor and just made a cover plate.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Fastrax, Thanks for the info.

    I read a Dal motorsport article that said the motor is for cruise control. Are you sure the motor in my first post photo is for the TCS?

    If it's for the TCS, I would like to remove it and put in storage along with the TCS brain/box. I guess that would save some weight and make things a little less complicated.

    Can anyone confirm that the motor is for the TCS and can be removed without any affect on a non-TCS controlled car?
    Last edited by stevenlee; 11-15-2009 at 16:39.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    I applied some penetrating oil and after allowing it 3 hours to penetrate, the valve is still frozen.
    I then temporarily removed the stepping motor and the valve is still stuck.
    Perhaps it's the throttle position sensor that is seized. I'll let the penetrant soak overnight and hope for the best.

    I am wondering if the stepping motor controls the throttle valve for both cruise control and traction control. I don't need it for traction control but would like to keep the cruise control function.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Thats some nice port work.
    NSX, making drivers smile since 1991.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    David,

    Thanks for the compliment. In my former life I spent over 30 years polishing gold. In fact, my first job title (not counting picking pineapples at age 15) was called "Filer" at age 16. I literally hand filed and deburred casting imperfections off gold castings for 40 hours per week. Doing the aluminum intake manifold was fun because it is so big compared to gold work.

    Update..... I removed the cruise control motor and the valve is still stuck. I applied more penetrating oil and waited a day and it's still frozen.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    This is a total WAG, because I don't know the specific construction of the valves, motors, etc involved. But, is it possible that the brake cleaner or carb cleaner melted a plastic/nylon/etc bushing? That bushing could then re-harden in place and freeze a shaft. So, if you spray one of those original cleaners back in there, then it might soften the bushing again for a short period of time. As I said, its a WAG, and probably a desperate solution..

    I was on vacation in Maui last week, but left my laptop at home and so didn't check-in on Prime. I don't know which island you are on, but if it's Maui, I could have at least stopped by and bought you a beer to lessen the pain.
    Frank
    '96 NSX-T, red/tan
    '01 SLK 320
    '84 Z51 'Vette

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Frank,
    I am thinking the same thing. Thanks for the psychic beer. I'm on Oahu.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    cruise is controlled by a solenoid separate and attatched to the gas pedal IIRC. it has nothing to do with this.

    have you tried force? this happened to me the other day from sandblasting and i had to use a mallet and pop it loose.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    I tried tapping on the valve with a 12 mm wrench but didn't get it to break loose. I sent it out to a shop to be dismantled and cleaned.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    I think when you welded the Wiggins clamp on maybe you've warped the Throttle body or melted the bushes.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    The Wiggins clamp flange was welded 5 years ago and it only got stuck recently after I sprayed carb and brake cleaner on the throttle body to wash out sanding debris. But, thanks for your thoughts.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Quote Originally Posted by stevenlee View Post
    Fastrax, Thanks for the info.

    I read a Dal motorsport article that said the motor is for cruise control. Are you sure the motor in my first post photo is for the TCS?

    If it's for the TCS, I would like to remove it and put in storage along with the TCS brain/box. I guess that would save some weight and make things a little less complicated.

    Can anyone confirm that the motor is for the TCS and can be removed without any affect on a non-TCS controlled car?
    Have you fixed this?

    I 2nd FastraxTurbo's advice. Per pg. 19-78 of the service manual, it looks like the TCS throttle actuator could be interfering somehow.

    Since I don't have TCS/ABS anymore I was planning on removing it soon myself.

    Dave

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    Re: Throttle body butterfly valve plate is stuck in closed position

    Mac Attack,

    I removed the TCS motor and the butterfly was still frozen shut. I sent the throttle body out for repair.

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    Re: Throttle body butterfly valve plate is stuck in closed position

    stevenlee,

    I meant removing the whole right side of the TB. The internal gears may be bound somehow, but it seems somewhat unlikely.

    Please let us know what was causing it to freeze!

    It looks like DAL permanently removed the right side of the TB and made a jumper from the accelerator pedal opening sensor to the throttle valve opening sensor since they're the same output (pgs 19-114 through 19-116).

    Dave
    Last edited by Mac Attack; 11-27-2009 at 09:28.

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