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thefingD

1990 subaru legacy L... Sensor prob? wiring prob?

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Ok so currently I had to swap the engine in my subaru legacy "L". It has a 2.2 multi fuel injection engine manual transmission. Thats what it had before and thats what I replaced it with.

 

At the start the engine swap went ok for a few minor problems. Wiring harness was different etc. So i took the old parts off my other engine and it worked fine, EXCEPT!!!

 

Did fine on the streets, mostly flats, but it would lose tons of power going up hills. It felt like it wasnt getting enough fuel. So I took the injectors off the last engine, ones I knew worked and swapped them out.

also swapped out the spark plug wires. The engine doesnt shake, and sounds good at idle, so Im not thinking its a spark plug problem.

 

Car ran fine for a few miles when my temp gauge shot up and my RPM gauge was all over the board. RPMs would drop to zero and then up to 4000 and just constantly up and down. When i went to pull over it stopped idleing and just died there. It felt like the power was turning on and off and it felt like I was in the Burmuda triangle. The guages where going hay wire, and not making any sense while the car was doing a bit of jerking. And I could hear a bit of clicking in the dash, like the same sound when you twist the knob on a lamp. But just the RPMs and the Temp were malfunctioning, speed o meter and other guages not effected.

 

when i pulled over there was a little bit of smoke coming out of my engine so I think it was actually overheating not just giving a false reading. Once when a plug went bad it said I was hot all the time,

and the lights would stay on in the dash even while my key was out. Its similar to that issue but not quite. When I take my key out now, all lights turn off, and my car seems to be actually overheating.

 

Also my engine light is on constantly... no blinking.

 

My dad rebuilds cars for a living, and has a computer diagnostic machine, just the plugs dont work for my older model of car... Im thinking knocker sensor? bad fuel injectors? Do you think Im going to need to get the plug that works for my car and his diagnostic tool?

 

But it feels like an electrical issue.

 

If anyone has a clue Id really appreciate hearing what you all think. This car is my baby I want her to live.

Edited by thefingD

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Odd, almost sounds like a bad alternator to me. If it still runs at the moment, I would def check the charging voltage while the motor is running. Next, don't go blindly replacing parts until you see what your check engine light is. Don't guess and waste money, that's why the OBD system is there. Look under the dash on the drivers side, you will find two green connectors. Connect them and turn the key on. The CE light will start to flash all the trouble codes stored in the system. Long pulses are 10's, short pulses are ones. Ex- 2 long pulses and 3 short pulses would be code 23. If there is more than one code they are seperated by a long pause. Here is a list of the trouble codes for your vehicle

 

http://www.ultimatesubaru.org/forum/showthread.php?t=49918

 

Your set of codes is the very last one on that page

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How does it sound like a bad alternator?

 

Ive driven without an alternator before, I could only imagine it wouldnt matter until the battery ran out...

 

Remember overheating and mis calculating RPMs.

 

Thanks for the codes though...

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Sounds like the alternator to me also. Over-voltage and AC current most probably.

 

Did the engine actually overheat or just a high reading on the gauge?

 

GD

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There was a bit of smoke coming off the engine, so I suppose it was overheating.

 

 

Once when the wiring harness wasnt plugged in all the way the temp gauge went to the max and stayed there... but there wasnt any smoke or anything that time. So I guess its possible it wasnt really overheating, but it seemed like it.

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I dont get it though... my battery is still getting a good charge. The alternator runs to the battery and the actually power comes off the battery... so it shouldnt make effects on anything other than the charge on the battery, right?

 

Im going to do the self diagnostic in an hour. Hopefully I get a helpful reading from that.

Edited by thefingD

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You have a very simple, and incorrect, mental image of how electrons work. Trust me when I say a bad alternator can and will make your whole electrical system freak out. Get it tested.

 

GD

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For the sake of curring my basic and incorrect understanding, why would it effect it?

 

 

Ive made wind generators out of subaru alternators, and its not much different. Alternator goes to a charge regulator which then goes to a battery which goes to a converter which hooks into a fuse box.

 

Enlightenment would be greatly appreciated :)

Edited by thefingD

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I plugged the two green wires together under the dash. There was no LED to be seen, and the check engine light dimmed but wasnt blinking at all.

 

Oddly enough the fans on the radiator were turning on and off every second. I let it do it for about 30 seconds, with no change in tempo or dynamics.

 

If its the Alternator couldnt I just unplug it, and it shouldnt have any problems until the battery loses a charge?

Edited by thefingD

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Alternators can fail in both ways. They can fail to charge, and they can overcharge. You may have experienced the fail to charge but I bet not the overcharge.

 

Its entirely possible you were overheating as well. Where did this replacement engine come from and how do you know it was good?

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An alternator produces alternating (AC) current. That is passed through a bridge rectifier and then through a voltage regulator. If either of those fail the alternator can emit AC current and/or can produce voltages higher than 14.5. Either of these will have adverse effects on various circuits in the car. Sometimes it will burn stuff out (bulbs, etc), and sometimes AC current will defeat diode protected circuits and illuminate the "christmas tree" and other odd behavior can and will occur - gauges will read incorrectly if not given the voltage and/or current type they expect.... etc.

 

You should do some searches - this is covered fairly often.

 

GD

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my dad owns a junk yard and he had a legacy that was a 91 that was hit in the back. It had only 100k on it and a perfect interior... all around the engine there were markings where the owner noted oil changes and it seemed loved. I never really started it until the swap. It drove great around town until I noticed it wasnt going up hills well. Which led to figuring it had clogged fuel injectors

 

In short I had no idea that the engine is good. I drove it for a week before I noticed it wasnt going up this crazy steep hill. After I swapped the injectors off the old engine (Old engine leaked tons of oil and its seals sucked so this engine was easier than changing the headgaskets) so I knew they worked. I drove hard for about 5 miles, I was really testing it taking up to 60 and driving 20 in third to hear if it would stall. Sounded great until about 5 miles in it was like I hit the Bermuda triangle and everything went to hell.

 

I think it has to do with the wiring harness. The new engine has a slightly different wiring harness. On the drivers side of my car behind the battery there are 3 fat (2"x1" or so) plugs. The new engines harness only had 2 there.

I swapped the harness off my old engine and it had everything I needed to complete all the connections. When I first put it in I would take out the key and all the dash lights would stay on, but dimmer. And when I turned the key it wouldnt start. I pushed on the plugs and it fixed the problems.

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As others have stated already a alternator can have excessive ripple voltage that will cause crazy things to happen with the electrical systems. The DC voltage can still appear to be fine, it is the AC voltage component that is messing with things. A simple way to prove the trouble is coming from the charging system is to disable the alternator by shutting the engine off and then remove the plug on the rear side of the alternator.That will kill the exciter and the charging action. Restart the engine and if things now return to normal by just running off the battery you know what to do to fix it.

Edited by Cougar

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Cool thanks alot you guys. Im going to go out tomorrow and totaly check on that. I really hope its the alternator cause I got like a dozen of them out in the yard... just a matter of finding a good one. lol.

 

 

:banana::banana::banana::banana::banana::banana::banana: :banana:

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Ok so I disconnected the alternator, and there was no change in the engine.

 

I plugged the two black wires together and I got these codes.

 

 

32 Oxygen Sensor or Circuit

35 Purge Control Solenoid or Circuit

41 Air/Fuel Adaptive Control

22 Knock Sensor or Circuit

24 Air Control Valve or Circuit

 

 

What do you guys think?

 

Considering I allready had a little issue with the wireing harness could all of his these things be running on one plug or something? Also the engine sat for about a year before the swap... could all of these sensors be bad?

Edited by thefingD

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Being a '90..... they have phantom code issues. Both '90 and '91 tend to do that... they will throw half a dozen codes at you and seemingly be unaffected. I have a customer with a '90 that threw 6 codes at me one day.... wouldn't clear them.... but ran perfectly fine and gets 30 mpg.

 

I would start with code 35 - since that's an easy fix and quite likely that the solenoid is bad as that happens a lot. It's under the passenger side of the intake manifold runner..... test it and if it's bad replace it or solder in a 33 Ohm, 5 watt resistor in it's place to fool the ECU. It just wants to see the resistance from the driver coil.

 

41 I have never seen before. That's a strange one.....

 

The rest are pretty common. I would test the solenoid and see if it's bad and then go from there. If it's not bad then you probably have a wireing or ground issue.

 

GD

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starting to think I miss read 41 and its actually 31 (Throttle Position Sensor or Circuit) that sounds like it would be more in the same category as the other error codes.

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Im fairly possitive now that it is the engines wireing harness. I took the car around the block a few times and when I got back I jiggled the wires and it killed the engine. When the engine was off I kept jiggling and it was turning my radiator fans on and off. Also while it was doing that it was making a loud clicking noise, which is the same I heard while it was going all hay wire.

 

If I cant find a cheap wireing harness, do you think I could get by with just splicing the wires together? Solder or butt splice?

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I would almost bet on the harness now also, since you said you were having problems with it earlier. And all of the codes being thrown are in that harness. When switching motors on a Subaru, the best thing to do is always install your old intake manifold onto the motor you are swapping in.

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Because you are retaining the same engine harness, same sensors, same IAC, TPS, etc etc, you get the idea. Make sense? Your just changing the physical engine, not any of the electronics.

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Cool. So do you think its safe to just solder or use quick connects on the wires? I dont have another wireing harness with the same plug setup.

Edited by thefingD

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Where is it that you are planning to solder? If you mean removing the main connectors that attach the engine harness to the car harness I would not do that... I would try to find the real problem and if it's actually the connector itself then source another harness. Any 90/91 non-turbo manifold harness should work.

 

Butt splices are for temporary work only in my book. They are NEVER ok for permanent wiring jobs. When I worked for a manufacturer of industrial equipment butt splices were explicitly disallowed by our wireing guidelines. If you need to joint two wires you can use many methods but a crimp-type butt splice is just asking for problems down the line. If you must use one then use the heat-shrink variety that can be sealed from the elements.

 

GD

Edited by GeneralDisorder

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Right next to the battery there are 3 main plugs that come off the wireing harness. They then direct themselves into the fuse box. 2 of the are almost square (2" x 2"1/4 or so) and the other is smaller (2" x 1"). I was going to splice through that plug.

 

It wont make things easy when I want to disconnect it because id have to remove the heat shrink and 8 little plugs... apposed to 1 large plug. But...

 

 

I was going to use something like this, and then cover each wire in heat shrink. Maybe add a dab of solder to it for extra hold and conductuity.

 

wire_connectors.jpg

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