mack123

iTrader: (4)

hey all, I recently bought an 88 turbo. I was a N/A owner for like 15 years.

I noticed on my N/A throttle body the 2 front throttle plates are alwys open,at rest. this is right.

YEt my turbo throttle body has the 2 bottom front butterflies closed at rest,along with the single butterfly on top closed too. {back 2 plates are closed too.}

Is this right? or are the bottom 2 plates supposed to be open? maybe someone before me was messing with it.

also, So with the opening clearance,fast idle clearance test, are they talking about the back 2 plates or the front ones, measured when they start to open ?
thanks all
mack

J-Rat

iTrader: (2)

At rest, the 2 throttle plates on your N/A should have been closed too. Its called the double throttle system. It directs air through the one runner at low revs/vacuum in order to increase air speed down the runners at low revs.

HAILERS

Errr, ahhhh, on a non turbo, the outboard set of plates should be wide open once the water temp has gotten up to temp and the car is idling/running.

On a non turbo the outboard set of plates should be spring loaded to the wide open position. When a non turbo car is cold and the water is not up to temperature, the outboard set of plates will be held closed by vacuum from the double throttle diaphram......but will go wide open once the water thermo device closes and cuts off the vacuum to the double throttle diaphram.

On a tuirbo, and thats what your really interested in right now, the outboard set of plates are held closed with a spring all the time, UNTIL the throttle is stepped on and then thru the linkage there, they will be pulled wide open, UNLESS the water is still cold where upon the double throttle diaphram will hold them closed until the water gets up to temp.

Take a close look at the front of the turbo throttle body and observe the black cam that rides against a damper with a plunger. This plungers tit wears out and caused the outboard set of plates to stick closed on occasion. That results in grumpy boost. Sometimes they will open and the car will boost just fine....other times they will stick closed due to the worn dampers tit, and the car will half *** boost.

I have a car that has the symptoms of the above paragraph. I disabled the thin spring with a rod going thru it and zip tied the number 2 throttle plates to the open position and have had zip problems since. It's my version of the throttle body mod....expcept it takes but fifteen minutes to do vs the god awful mess the other mod makes. Plus...its reversible and the car can be restored to the original config.

Note: The outboard set of plates are called the number two secondary throttle plates. I just thought saying the outboard set made more sense in describing them. Bottom line MACK123 is that your throttle body sounds as normal as can be.

OH! By the way, it sounds like your non turbo car had a broken double throttle diaphram which resulted in the outboard set never closing and being open all the time. Personally I have never seen a working double throttle diaphram on a non turbo car. I never could find a working one in a junk yard to replace mine....but I do know how they work and why mine were always wide open (busted diaphram).