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BOOM (mystery sensor?)


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11 replies to this topic

#1 baccaruda

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Posted 04 October 2003 - 09:42 PM

well, it looks like i'm swapping tyrel's XT engine into my wagon RIGHT NOW. My wagon snapped a timing belt (strange, one of the things I WASN'T worried about dying) and with the bad cylinder, oil pump, and waterpump, it's easy to see why i'm doing the swap instead of changing a timing belt.

The funnest part of all this will be changing the wiring harness, of course.
The throttlebody on both cars has a brass hexagonal sensor; small with one wire on the GL10 and larger with two wires on the XT. Should I get an adapter to use my car's smaller sensor or choose a wire to use off of the 2 wire sensor? maybe ground the other one?

Chris, how's it going with that flipped TPS trick? I'm looking at doing the same thing real quick here :P ..
Would disconnecting one of the 4 wires out of the XT TPS make your car able to read it as the GL TPS?

thanks...

#2 baccaruda

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Posted 05 October 2003 - 10:15 AM

boink

#3 ezapar

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Posted 05 October 2003 - 10:43 AM

Tex said he'd be East of the mountains this weekend. Probably not near his computer.

#4 Skip

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Posted 05 October 2003 - 02:09 PM

Andy, on the mechanical end, make sure you snag the dogbone (pitching stopper) from the XT.

on the electrical, I have been trying to help Tex with his conversion.
You do not say what year, fuel system (flapper door or Hot wire MAF) and if the XT donor is a turbo.

The TPS is a different and may not (as in Tex's case) swap.
If you have a multimeter, you can check the GL's TPS and if the XT's is the same FI system rewire to match.
There may be a separate plug for the idle switch which is incoporated in the TPS.
I am not aware of the brass "sensor" you sure it's not a aux air solenoid for when the AC is in op? I know of no "sensor" in this area aside from the TPS

#5 baccaruda

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Posted 05 October 2003 - 10:46 PM

hi skip... the part i'm trying to figure out now is what to do about this sensor that i've circled in the attached picture. it has some sort of vacuum function to it. my car's is smaller and has one wire out; the engine i'm putting IN the car is larger and has two wires out of it, one goes directly to ground. I'm not sure which sensor to use or what to do with it. i'm not even sure what the sensor is.

since the two-wires setup just sends the other wire to ground should i just splice the two together into one wire to send out?




i've got the throttle body sensor taken care of. they both do the same thing but they move different directions. so i've "trimmed" my TPS a little to allow stock mounting and i'll switch the two outer wires with each other to handle the differing direction problem.

luckily i had a few extra TPSes and mystery sensors to dissect.

Attached Files



#6 Subarutex

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Posted 06 October 2003 - 02:15 AM

Andy, could you get me some pictures of your TPS's, and what you did to try and make it work?

I have some sad news on my TPS battle. I thought it was working, but my TPS is crazy. The readings are all over the place (that i'm getting from my throttle % gauge on my S-AFC) This is making my car run a little leaner than usual. I'm 1200 miles through my 1500 mile journey. TPS hasn't been working right the whole time. No damage yet. Just have to watch the A/F on boost, cause its running way lean. However, i'm now getting incredible gas mileage. I'm fairly certian this is the cause of my lurching/lugging/surging however you want to describe it.

Now, I need to deduce if its the TPS, or my wiring. The TPS end of my harness has been hacked up, and so has the leads on my TPS. Its hardwired now (no connectors). So I may be in need of another harness, aswell as another TPS. I'll keep you posted as to what happens when I get home. (i'm in Pullman now, leave tomorrow eveningish)

#7 Skip

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Posted 06 October 2003 - 04:57 AM

Andy, the devise you picture is what I said it was.
It is the fast idle solenoid and not a sensor.
It increses the idle when the AC is on to compensate for the compressor drag. Wire it with which every wireing harness you are using or, if you are not using AC -fe getaboutit.
One wire to ground the other gets battery voltage when the AC is in op. (Sorry for the corn fussion, maybe you thought I ment aux air valve (AAV). The devise you are talking about is better called "fast idle solenoid".)

As for the TPS, as I mentioned they are different for vane style MAF's and hot wire. No mention of the system.
Must match the system to the TPS and the idle switch.
HTH

#8 baccaruda

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Posted 06 October 2003 - 05:11 AM

Hi Chris.. how did you get yours wired in? You drilled a hole in it and put it on backwards and left your wires alone? and your car is supposed to have the three wire setup, right? maybe it's not adjusted quite right? I can't say how mine works yet as I've not even taken the old engine out of the car yet.. but since the 3 wire turns backwards compared to how the 4 wire turns, i figured i'd let it turn backwards and switch the two wires that the middle one makes contact with in different throttle positions.

Skip.. thanks for cluing me in on that. My car's FIS has one wire and is smaller; the XT engine's FIS has two wires, one to ground, and is bigger.. meaning that the smaller one is too short to fill the XT's FIS socket deeply enough and it's too small to even screw in. that's the problem.. I think I need to come up with a way to make the larger 2-wire FIS send the right stuff to my car.. any ideas?

#9 Subarutex

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Posted 06 October 2003 - 01:33 PM

Andy:

My car was equipped with the 3 prong TPS. (main black connector on the black box) This turns out to be actually the idle switch connection. The TPS connection is a seperate 3 prong cylinderical white/yellow connector.

First I had tried to wire a 4 prong (black connector on black box) NA TPS to my harness. Cut the connectors off the harness, wired the 4 prong plug on. Using educated guesses (from the FSM) to wire it. This didn't work. I was getting 100% throttle when the gas pedal wasn't even pressed. So enough gas for 100% throttle, but only idle air flow. Was passing a lot of smoke through, and the turbo started to steam. I think it was gas vaporizing as it hit the hot turbo.

Second and current solution was to rewire my old TPS. I was able to wire up the 3 prong black connector no problem (found off another harness i had laying about) for the idle switch. However, i had thrown away the old cylinderical connector, so I just ended up cutting it, and using butt splices and some wire to connect up the TPS. I just matched color to color.

Prior to all of this, i had removed the cover, and drilled a hole directly above the hole in the sensor so that I could mount it flipped over. I found some longer screws (had to cut them down to size actually) that fit, and used those to secure it.

At first it seemed to work, but honestly i was still having too much fun actually driving my car, than paying 100% attention to all my gauges. Since I got it running, its always done the jolting thing.

An example of my bad TPS: Driving through idaho, going 65, not in boost. A/F ratio about 13.5-13.7. Throttle reads 60%, i'm giving it probally about quarter pedal though, just to cruise.

I go to pass someone. Kick it up to 12 pounds of boost, WOT...pedal on the floor. A/F goes through the roof....14.5-14.9 No good for a boost situation. Throttle reads 10%. I back pedal, giving up on passing this guy.

I checked the TPS parked, with Monica looking at the % readout, to see what was up. Just wiggling the throttle cable made it hit 50% throttle readings. When not touching it, it would read 20%, or 45% sometims 5% (which is where it usually read at idle before the swap)

#10 RedLance

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Posted 06 October 2003 - 01:56 PM

Andy

The little brass thing is NOT a sensor, it is an actuator.

Use the XT one, as it fits, leave the one wire connected to ground, as it was in the XT, and connect the other wire to the wire from your car.

The smaller one, from your car, just didn't have a ground wire, as it grounded through it's body.

It dosen't send to your car, your car sends to it. It's just a 12volt solenoid. When the A/C is on, your car sends 12volts to this brass thing, and it opens a valve, so your idle speed will increase, to compensate for the load that the A/C compressor adds.

If you don't have A/C, just leave it unhooked.

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#11 calebz

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Posted 06 October 2003 - 02:11 PM

Just a note on that Idle solenoid... mine acuates when I turn the heater on too.. is it supposed to do that?

#12 baccaruda

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Posted 06 October 2003 - 06:41 PM

hi guys, thanks for the info. i called subaru stuff in hayden ID and he said the same thing about the internal grounding. I also asked him about the air bypass valve normally on top of the thermostat and he said they're the same too.. looks like i'm good to go!
thanks again. *end panic*




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