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Difference between TBs?


88StarionESI-R
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I was wondering if the TBs are interchangeable between different years of Starions?  I found a 86 or 87 flatbody in the junkyard.  The TB looks like my 88, but I can't be sure if there are any differences that I couldn't tell.  Also, is the head same as an 88?  I was thinking I can rip all the internals from the head and use them to rebuild onto a new non-jet valved head.

 

-88StarionESI-R

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The later throttle body units are pretty similar.  Those from 84-86 cars with the firewall mounted pressure sender have an extra port in them; this port is drilled and plugged in the 87-later t-bodies.  83s are a totally different animal however.  As far as I know, you can use an early model t-body on an 87-later car by just plugging this extra port (it's near the "row of three").  You'll need an 87-later style ISC/MPS package though.

 

The 87-later ISC/MPS is one assembly... that bracket screwed to the firewall side of the throttle body.  If it has an MPS (Motor Position Sensor) there will be a round cylinder shaped protrusion on the top of the bracket - about 5/8s of an inch in diameter, almost half an inch tall.  There will also be two connectors coming from the assembly: the one going into the assembly near the motor and a second one going past the motor - these are the MPS wires.

 

Mitsu used the same basic ISC/MPS package on a few other cars, with different mounting brackets.  You can get them from older Galants and Mitsu-engined Hyudais too - just swap the brackets.  Generally those cars have compatible TPS units as well.

 

mike c.

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mike,

  Thanks for the reply.  That was very informative.  So, 87-89 TBs are all interchangeable.  To use 83-86 TBs in 87-89 cars just plug the extra port and use a ISC/MPS from 87-89 TBs.

 

Is the ISC/MPS assembly the one in picture 5 here? (TBHEX05)

http://www.starquestgarage.com/howto/tbhex/tbhex.html

It'sthe round cylinder looking thing that's laying horizontally under the yellow "D" "D"?

 

Can you point out where the extra port be in the 6 pictures?

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TBHEX05 shows the 87-later style ISC/MPS assembly... actually all of those pictures show the later style.  The MPS is under the round bump near the two black wire clamp things...  in TBHEX05, find the uppermost "D" - right above the left hand wire clamp... the MPS is underneath the round bump that's at 4 o'clock from that "D" letter... and it has a "C" next to it as well:

"D"

  MPSbump

                 "C"

clamp  clamp

 

I'm not sure what "round cylinder looking thing" you meant since several things can fit that description.  The MPS is under the wart/dome/bump in the ISC/MPS mounting bracket assembly - the MPS dome points straight up when the throttle body is on the car.  The early cars (pre-87) don't have this bump.  Okay, I just re-read your message... I think by "round cylinder looking thing" you're referring to the black thing to the left of the "D"'s, right - with a goldish/yellowish metal strap on it?  That's the ISC motor itself - just a small DC motor.  

 

The 83 throttle bodies, I think, have a slightly different bolt pattern where they attach to the intake manifold.  They also have a slightly larger throttle plate I believe.  At least that's what I remember hearing; I've never examined one myself.  Plus, the injectors on the 83 setup are trapped inside the assembly and mount quite differently.  84-88 t-bodies can be used on the 87-later cars (a later t-body on an earlier car would be missing the port for the pressure sender).  In picture TBHEX02 you can see 3 vac ports in a row at the bottom/center of the photo.  If you look closely just above the right-most port you'll see a small goldish spot... that's the port that is drilled & then plugged on the later t-bodies; on the earlier cars there is a vac port here.  You'll also see a "rib" molded into the case with what looks like a hole drilled through it (going left to right in the photo); this isn't a vac port - I have no idea what it is.  A leftover from some other possible use of this t-body most likely.  The goldish spot is below (and slightly to the right) of this drilled thing.  You just cap the gold port to use one of these early t-bodies on an 87-later car.  And swap the 87-later ISC/MPS assembly onto the t-body of course.

 

mike c.

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Once again, thanks for the very informative post.  The details are incredible.  :)  I was able to find the MPS from your description. It's shown here:

http://www.tristarion.com/htmlman/fuel-sys...-system-73.html

number 21, pointing to 7 o'clock.  and I see the ISC motor that I was describing.  It looks like the TB I found at the junk yard is an 87.  It has 3 ports and the plugged 4th.  I'll go back and pick it up.

Lots of info in here.  Perhaps this can make it into the Faqs.

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