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Will EJ22 idle w/o throttle position sensor ....


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14 replies to this topic

#1 ballitch

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Posted 04 February 2005 - 06:35 PM

As the title says, a little background info first. the 1991 legacy harness i got has a different throttle pos. sensor than the 1996 motor i got for my EJ22 conversion, question is will the motor idle with wiring all hooked up and grounded and all that jaz. the wire colors are totally different and my damn chiltons manual doesnt have s**t on the wiring in detail like i need it. im thinking if i hook all but the throttle pos. sensor up, if it WILL idle then i can just experiment with wire combinations until i get the right one, problem is the 1996 throttle pos. sensor has 3 wires, the 1991 harness has 4. Just need to make the computer happy and get that B**CH on the road!!!! any input is appreciated.




~Josh~

#2 garner

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Posted 04 February 2005 - 07:38 PM

It should idle with out it. Computer will throw codes etc but it aught to run.

The 3 wire sensor is basically a switch (idle, not idle, and WOT)

The 4 wire is a reostat type thing that provides a more accurate idea of where the throttle is.

Wiring the 3 wire TPS to a 4 wire harness won't really work to well (I had this set up on my Brat) You will eventually need to get the proper 4 wire TPS

even though it's for impreza and much newer, this online pdf manual may help

http://ken-gilbert.c...eza_manuals.htm

GETERDONE!

garner

#3 Legacy777

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Posted 04 February 2005 - 08:32 PM

Actually the 4-wire tps has the idle switch built into the sensor.

The 3-wire sensor does not have the idle switch built into the sensor.

You should try and find a 4-wire tps.

Here's a pic of the 4-wire tps. You can see the idle switch point

http://www.main.expe...hiltons/TPS.jpg

#4 ballitch

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Posted 05 February 2005 - 02:16 PM

i have the 4 wire tps, only problem is i have a throttle body for a 3 wire tps. if anyone could help tell me how to wire the 3 wire throttle body into a 4 wire tps it would be cool, or if somone needed a 3 wire throttle body and has a 4 wire tps throttle body, or if someone could tell me how to "adapt" the 4 wire tps onto a 3 wire tps throttle body.



guys...............guuuyyyyssss............................................................guys.............................






~Josh~

#5 Legacy777

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Posted 05 February 2005 - 08:36 PM

Does the 4-wire tps not fit on the 3-wire throttle shaft?

I'm not sure where the idle switch on the three wire throttle bodies are, or if there is one. If there is one, you'd just wire it to pin 1 meant for the 4 wire tps, and then wire the remaiming 3 wires to the 3-wire tps.

If there is no idle switch, you have to get a 4-wire throttle body.

#6 ballitch

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Posted 05 February 2005 - 09:55 PM

ya the 4 wire tps has the hole in it for the shaft of the thr. body, just a hole though, the 3 wire one has like a flat piece with 2 little finger-like things that move the tps, not even close to being switch-able. if i had a digi and knew how to post pics i would sho ya..........im just going to have to find a 4 wire thr. body or something i guess. anyone got one that they dont need, trade me for mine? cmon you know you want to.






~Josh~

#7 rallyruss

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Posted 07 February 2005 - 01:04 PM

three wire systems no longer used the idle switch in the ECMs programing. it checked TPS signal voltage on start up and used that as its base line to determine closed throttle. if you had the urge to put your foot on the throttle then it knows to use the last good reading.

now the four wire system uses the same type of potentiometer for the TPS but also has a closed throttle switch built into the sensor as well. that is the 4th wire.

now if you are using a 91 harness I would assume that you also are using a 91 ecm.
if so you can adapt the TPS singal from the 96 sensor to the 91 harness/ecm but you cannot give it the proper closed throttle signal without adding a microswitch mounted to close when the throttle closes.

so to adress the original issue. will it idle without the proper closed throttle signal. yes I think it would most of the time. It may have a unstable idle and possibly have problems with cold starting.

I looked up a little info for you.
on the 91 harness for the TPS.
pin1 Brown (closed throttle switch)
pin2 black (ground?)
pin3 red (referance voltage?)
pin4 white (TPS signal wire)

question marks - untill I look at a better reference I am not positive.

on the 96 the diagram is horribly un detailed all I can say for sure is that pin 3 is the TPS signal wire.
if you intend to try and run the 96 sensor on the 91 I can get some more detailed info as to what to splice where. let me know if you need it.
good luck.

#8 garner

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Posted 07 February 2005 - 01:12 PM

I looked up a little info for you.
on the 91 harness for the TPS.
pin1 Brown (closed throttle switch)
pin2 black (ground?)
pin3 red (referance voltage?)
pin4 white (TPS signal wire)



I think you're right on Russ. These are the wire colors I have on my 88 spider intake harness and they seem to line up with the pins in the TPS itself.

Ballitch, you need to get a hold of a FSM for the harness you're using to try to make it work. Like I said, when I was running a 3 wire sensor and a 4 wire harness, it was not happy, try to source the proper TPS and you'll be good to go.

garner

#9 ballitch

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Posted 08 February 2005 - 03:13 AM

awesome rally, thanks for the help sure-nuf when oyu need some info, contact the board. problem is i have both thr. position sensors, only catch is the 91 harness uses a 4 wire sensor which i have, i also have a 3 wire sensor, and a 3 wire throttle body, but no 4 wire throttle body, i know that all the material i look at is inconclusive, except for your info rally. i will try to wire it up soon after a little more R&D.......if oyu have anything you can add to this, anyone, please do so, even if you think im stupid for not checking this earlier on, shoulda seen something like this coming. anywho, thanks guys.



~Josh~

#10 ballitch

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Posted 08 February 2005 - 03:17 AM

oh, and yes im using 91 ecm. just had to switch engine harnesses on the intake to match, thought 96 plugs would match up, yeah right, what a W.A.G that was.



~Josh~

#11 rallyruss

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Posted 08 February 2005 - 01:58 PM

ok if you are going to do it please rember that it may not idle well with a missing closed position switch. I would consider wiring in a good micro switch. or find that other throttle body.
Good luck

#12 ballitch

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Posted 08 February 2005 - 04:12 PM

and by micro switch you mean toggle switch? the 3 wire tps has a wire for closed, full, and idle.....or is it closed, full, and reference? i guess i could always try to gerry-rig something up to where the 3 wire thr. body is moving the 4 wire tps.............i dont know ill try it and find out i guess, hope i dont fry anything.




~Josh~

#13 rallyruss

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Posted 08 February 2005 - 04:29 PM

and by micro switch you mean toggle switch? the 3 wire tps has a wire for closed, full, and idle.....or is it closed, full, and reference? i guess i could always try to gerry-rig something up to where the 3 wire thr. body is moving the 4 wire tps.............i dont know ill try it and find out i guess, hope i dont fry anything.




~Josh~


the three wire is the same as the 4 just without pin 1 (the throttle switch). dont guess at it. it sounds as though you need to look up how the TPS works then you will understand how it needs to work better.

#14 ballitch

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Posted 08 February 2005 - 04:37 PM

aight, cool. that makes a things a little bit easier. thanks rallyruss.




~Josh~

#15 ballitch

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Posted 08 February 2005 - 11:42 PM

oyu have to love PAP man, i looked in there, low and behold there was one 4 wire throttle body left and i un bolted it and all that happy stuff, ran home, unbolted my 3 wire thr. body and went back to PAP and swaped them, but i left the tps mounting screws in the old throttle body, the new 4 wire didnt have a tps on it, dagnabit. all good, thanks for the help everyone, very much appreciated.




~Josh~




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