Zootal

It was time. The door panels were falling apart, the paint badly peeling, the passenger side wheels both bent (cause my wife likes to hit curbs when turning), the rear end needed to be rebuilt, cat was shot, bad oil leak from back of engine, heavy oil burning...the list goes on and on. I was considering fixing these things, but this was the last nail in the coffin... It was a good car. Our new Subaru will probably not last as long - I wish I could get another car just like this only 20 years newer...

As I mentioned in my other thread - I finally gave up. I load tested all the power and ground wires, I tested every wire and sensor. Nothing is wrong. I finally decided the ECU was bad, the replacement was bad and my chances of getting a good one is not worth the $200 bill it would cost to try again. I retired the car. **sobs Donated it to Veteran Car Donations. Maybe someone will find some good parts in it... **sobs...

I actually went in and replaced the electrolytics. Sadly did not change anything. I checked every wire and every sensor that connects to this thing. Eventually I decided to stop throwing time and money a this car, and retired it. **sobs I've had that care for 20 years... **sobs... I still miss it. My wife has a 2016 Subaru. This old Legacy was a much better car.

FWIW, I want to thank all of you that have contributed to this thread. Your comments helped me think more clearly about this and prompted me to test a few things I would not have thought to test. This has got to be one of the best gathering points for Subaru expertise.

I actually opened it up and replaced the big electrolytic capacitors - there are four of them. Sadly, it made no difference. They were clean, dry and not bulging. I have a cap checker in a box somewhere, I might dig it out and test them just out of curiosity. Traditional wisdom says electrolytics don't last that long, but I've got 40 year old electronics with electrolytics that work just fine <shrug>.... I like the car, but where do you draw the line and stop spending money on it? Honestly, this car has cost me a small fortune in maintenance. Just about every small part that can go bad has - starter, radiator, p/s pump, it's on its third alternator, front steering rack, weird a/c problem that cost $500 to fix. The only thing that has not (yet) gone bad is the a/c compressor. OTOH, we are not in a position to replace it right now. I'm thinking of getting one more ECU just to make sure, before I make the decision to send it to the junk yard. I watched the ground and power in while it was glitching. It was as smooth as can be. My load tests to the power/ground leads showed them to be clean. And yet, turn on the key, and the injectors start chattering, fuel pump starts cycling and I'm wondering if there is a poltergeist living in it? For now, it sits in my garage while I think about it....

Just did. Jury rigged a 5 amp load (three tail light bulbs lol) and verified it draws about five amps. Tested every ground and every supply pin, and all of them are less than .1 volts from battery or ground. Well within tolerances. Dang. I think the ECU is bad. What else is left? The sensors are disconnected, and what is still connected is verified working with good wiring. I think these old ECUs just go bad eventually and I bought a bad one. I'm tempted to try yet another one, but that is a hundred dollar bill just to get one from another junkyard with no guarantee that it is good...<sigh>...

I thought of that - I once had a bad power supply blow a mother board, and I didn't realize it was the power supply until I put it into another computer - zap, two blown motherboards, but I digress... I thought I was pretty thorough when checking the connectors at the ECU, I checked voltages/grounds with it running, and then I pulled the connectors and checked continuity. Everything was as it should be. I disconnected just about everything I could, sensors, etc. Disconnected wire harness plugs leading to instruments, removed tranny control unit (cause it was in my way), unplugged everything I could. Still - turn the key on, and injectors and fuel pump cycle intermittently and after a few minutes, almost as if on a timer, the radiator fans turn on and won't turn off until you turn the key on. Oh this is even better - if I turn the key on again the fans come on immediately. The only way to get them to stop coming on is to put the ECU into test mode using the test connector, and then disconnect it. Fans shut off - until next time the seemingly randomly turn on again. I really don't know where to look next, or wtf is going on. Maybe these ECUs just do that after 25 years? 25 years for an electronic device is pretty remarkable. *Everything* I've done points to a bad ECU. It is, after all, the ECU that fires injectors, cycles the fuel pump relay, pulses the tachometer. The ECU controls all of this, and I don't see any power/ground or input problems, in fact it does this with most of the input devices/sensors disconnected. Retiring the car is approaching the top of my list - 25 years old, 230,000 + miles (or is it 280,000?). Burns oil, tranny shifts hard and whines, paint is peeling badly, visors broken, door panels peeling, seats need reupholstering. It looks like hell. Leaks oil, needs rear struts and brakes....driver side front auto seat belt doesn't work, drivers door doesn't shut right (cause it was wrecked and not fix right many years ago). It really is falling apart, and this is kinda the last nail on the coffin... Ok, sorry, I'm thinking out loud and venting....it's been a long day crawling under the dash

Well I think I'm done with this car. I traced the wiring to/from the ECU, checked voltage/ground at the pins, and there is nothing wrong. It has power, it has ground, most of the sensors are disconnected and what is connected is working fine. Everything points to a bad ECU, but I replaced the ECU and it's doing the same thing. What are the chances of the replacement ECU being bad? Even pulled the fuse block, inspected everything I could find to inspect, measured resistance from ground pins to chassis ground, checked b+ at power pins, checked the wiring for the sensors to make sure none of them had problems. There just isn't anything wrong that I can find. There is one pin labeled "Self-shutoff control". I'm not sure where it goes because I did not want to cut open the wire loom and trace it, and I don't see it in the wiring diagrams. Anyone know what that does?

Here is an update for anyone following this thread. 1) Replacing ECU did not fix problem. 2) I have discovered that just about any mild surge to the electrical system - turn signals, honking horn, etc. - causes the fuel pump to cycle and injectors to chatter, injecting fuel into a non-running engine. It frequently does it by itself, but I can easily trigger it just by turning on turn signals for a second. I can start the engine and it runs, even drive it, but it's a bit rough. I have unplugged most sensors under the hood, unplugged the fuel pump relay and put a test light across it so I can have a visual indicator of this happening. Today I'm going to drop the ECU and check all power and ground connections, and then all inputs and outputs. Why oh why did they shove it up under the dash where you can hardly get to it? I'm going to remove driver seat so I can at least lay down and get comfortable while doing this. I'm tempted to pull the instrument console just to see if it gives me better access to the wiring.

So if I unplug the alternator, the symptoms stop immediately. I can then start and run the engine and *everything* is perfectly normal (except it won't charge because the alternator is unplugged). I plug in the plug on the top of the alternator, and the computer immediately starts to cycle the fuel pump relay and the injectors. I'm going to trace the wiring from the connector to see if there is a problem there, or where it goes... Yes I tested the alternator, - auto parts store says it is good. I'm not 100% satisfied, but I need to examine wiring diagram and inspect related wiring before I'm ready to invest $$$ in an alternator that might not fix the problem. I mention this just in case this rings a bell with anyone...

Found wiring diagram for alarm - all it does is disable the starter. Pulled fuel pump relay and put test light across the pins that actuate the relay, and sure enough, it toggles on and off intermittently, ever couple of seconds. I think I'm going to end up doing this the hard way, tracing wiring into the computer and trace all the inputs and outputs. *Something* is causing the ecu to do this. It's a real bear to get up under the dash to the wiring <sigh> I think I'll pull the instrument cluster and see if that gives better access...

I think you are right about the fuel pump relay, and I think the ignition also goes through the alarm. It is supposed to shut things down if it thinks someone is trying to steal the car. I wonder if power to the computer also goes through it? I think tomorrow I'll take a closer look at the alarm box, see how they hacked it in, and see what goes through it. At least it's in the open and easy to get to, and if the power to the fuel pump relay and other things goes through it, I should be able to find it....thanks for being a sounding board, it's as good of an approach as any...

Here is another though - could the alarm controller cause this? It's not causing the relay click sound, it's actually hanging by a bunch of wires on the floor because I haven't tucked the wiring back under the dash. But could a bad alarm controller be the culprit? It's an aftermarket, forget the make. I think they are still available and don't cost that much.

Replaced computer. 1) Pulled spark plugs.One hole was flooded, I turned the engine with a wrench, and as the piston came to the top, about 4oz gasoline gushed out. Cleaned holes out, blew each one out with compressed air for good measure. Gave each one a squirt of spray lube. Disabled injectors and ignition. Cranked engine. Sounds good. Put plugs back in. 2) Start engine. Starts. Runs good. Purrs like a kitten. Idles as smooth as can be. HOWEVER.... When I turn the key on without starting the engine, there is a clicking noise from behind the instrument console. There is a relay there, and it cycles intermittently, no pattern. When it cycles, I can hear the fuel pump run for a second. Injectors click. CEL flashes. So I disconnected the fuel injectors so I could work on it without the engine filling up with gas. Interesting enough, I was able to get the CEL to flash the codes for fuel injectors disconnected. So the computer functions enough for the engine to start and run, and it detects the disconnected fuel injectors. And still, that relay behind the dash cycles on and off. The questions are - what is it, and what controls it? It's possible the relay itself is defective, or whatever drives it is defective.

The SAGA continues :-) Received ECU from junkyard today. Installed. Turn key on, did not start engine. Nice and quiet like it should be (before it would trigger the injectors and the tack would jump, with key on and engine not running). Now it sits there quietly, tach does not jump, injectors do not cycle, cel is steady. This is very promising! Tried to start engine. WHAM. Engine jumps, horrible pounding noise comes out of engine. I only cranked it for a second, it did not start. I stopped cranking immediately when I heard the noise. omg wtf now what.... So, come to find out that the ECU failure caused the injectors to cycle when the engine was not running, and this poured gasoline into the cylinders. I drained the oil pan, and I drained almost 5 1/2 quarts of fluid from it (this engine takes only 4 quarts of oil). Very strong gasoline smell in the oil. It pumped so much gas into a non-running engine, that it caused the engine to hydrolock when I turned it over, and over a quart of gasoline drained into the oilpan. I have not had time to do this, but my plan this weekend is: Pull spark plugs. Turn the engine over by hand and make sure there is no gas in the cylinders. I'm thinking bring each cylinder to the top, and stick a rag into the spark plug hole to soak up any excess gasoline. Then disable ignition and fuel injection, and crank the engine a bit to clear out remaining gasoline from cylinders. Install plugs, put clean oil in engine, replace oil filter while I'm at it, try to start engine. I just hope it didn't bend a rod or otherwise damage the engine.

I'm in Phoenix. Well, I have a Glendale mailing address because the Glendale post office services our neighborhood, but the city of Phoenix provides sewer/water/police etc. I have it torn apart right now, I unplugged a lot of stuff under the dash so I could get the ECU out. This problem started maybe a month or so ago. The first symptom was that it would stumble slightly at idle. Since this engine is extremely smooth at idle, it was rather noticeable, but not really that bad. As time went on, it slowly got worse. Then one day I noticed that with the key on but engine off, the tach would twitch, jump up to 500 rpm or so and then back to zero. It would do this every couple of seconds. Then one day I noticed that not only would the tach jump, but the injectors would rattle as if they were being fired. With the engine off. And when the engine did run, it would miss severely. Finally it got to the point where I did not trust it, so I parked it. Now, with the key on, ever few seconds or so the tach twitchs, the injectors rattle and the check engine light flashes off and on sporadically - it's not flashing a code, it's too sporadic. So I'm up to about 85% sure it's the ECU. If not, then I start tracing wiring - power, ground, crank sensor circuit. I suppose a bad/corroded connector somewhere might cause this, but I'm not looking forwards to tearing stuff apart to find it <sigh>.... If I unplug all of the sensors except the crank sensor, it still does it. If I just unplug the crank sensor, it stops. So I replaced the crank sensor, but that did not change anything. So my theory is that the amplifier/circuitry inside the ECU that picks up the crank sensor is bad and feeds spurious signals to the controller, causing it to fire the injectors and ignition. Not quite sure why/how that would cause the CEL to flash like it does

I pulled the ECU. Took apart. Nothing obvious wrong. Found a junkyard with an identical model, with same part number. $50. I'm betting at this point 50/50 or better this fixes it. If not, then I get to start checking wiring to/from ECU, but that is really really time consuming. I'd rather risk fifty bucks on an ECU before I start tearing into the wiring. it will be a week or so before I receive it, and I will come back here and post results after I get it and install it. Cross fingers for me!

Found one! Found several actually - sorry for taking up bandwidth here, it took a while before I finally found it. http://www.carpart.com. Their search actually flagged several of these. A junkyard in Winston Oregon listed on there, $70 shipping to Arizona included. Don't know how long it's been on the shelf. What is weird is the serial number ( I'm assuming it's a serial number, maybe it's a sub model number?) is 3521, and mine is 3525. If that really is a serial number, then my car and the one they have must have been right behind each other in the assembly line.... go figure....

I hope you don't mind a separate thread on this topic... 1994 Subaru Legacy Sedan. Auto transmission. 4DR. Front wheel drive. Looking for an ECM/ECU (whatever you call it). This is the engine control computer that sits under the dash on the left side, to the left of the steering column. Here are some pics: http://oi65.tinypic.com/lz6dz.jpg http://oi67.tinypic.com/102mo87.jpg http://oi68.tinypic.com/2hz0j1z.jpg The only one I've found so far comes from a 1993 Legacy. How interchangeable are these? Do I need one from the exact same year/model/etc? Or are they compatible from year to year? Anyone know of a source to find one of these? I'm still looking, but so far this specific model is rare, everything I'm finding is for a newer model or has different connector, different mounting bracket, etc.

I hear ya. I don't hire mechanics. I was one in the early 1980s (carburetor specialist and dang good at it), and while things have changed since them, they haven't changed all that much. If I can't fix this car, it goes to the scrap yard.

Interesting. I guess that is what they changed in 1995. I see a lot of references to this and that for up to 1994 model only. Is the ECU for these things, the one under the driver seat, the same for this model year (1994), or did they use different ones? I'm looking at junk yard units, and they all look the same.

1994, definitely OBD I. They changed something in 1995, not sure what, and in 1996 I think everything went to OBD II. Did Subaru go to OBD II in 1995? I have a Haynes and a Chiltons. Both more-or-less the same AFAIC. The wiring diagrams are fairly generic but for the most part close enough for what I need.

I'm looking at the manual, and all of these things - ignitor, crank sensor, fuel injectors - go directly into what it calls "MPFI control unit", 1990-1994 2.2L engine. I'm looking at a bad connection to this unit, a bad ground, something wrong with the power feed, something wrong with the wiring between the unit and the crank sensor - or the unit itself, in that order. MPFI - multi port fuel injector - is this thing a multi port system? It's the only diagram for the 1994 2.2L engine module.

So I replace the crank sensor. Sadly, nothing changes. It sits there intermittently cycling the injectors, the tach jumps, and now the check engine light flashes on and off irregularly - there is no pattern to it, it's not flashing a code, it's just flashing on and off as the injectors rattle and the tach jumps...<sigh>.... I know what the problem is not - it's not most of the sensors under the hood because I unplugged them all, and the problem persisted. When I unplug the crank sensor, it stops hence my decision to replace it. But with the new one, it still does the same thing. And I like doublechaz said, it's really unlikely it would send spurious signals and confuse the computer like this, but I had to replace it to be sure. So something else in the crank sensor circuit is confusing the computer, assuming the ecu itself is not bad. I'm beginning to wonder. My next step is find the computer, I think it's under the seat. Unplug it. Examine it. Check the wiring between the computer and the various sensors to make sure there is not a bad connection somewhere (that is gonna take a while). Then I think about replacing the ecu. As always, advice/suggestions welcome....

PS You are absolutely right. The crank sensor is indeed under the alternator. I pulled the alternator cause it takes 3 minutes to pull it and gets it out of the way. And the cam sensor is right were you said, also. My guess is that the crank sensor is sending spurious signals to ecu, which causes it to fire ignition and fuel injectors, which is what was happening, even with engine not running. I took it out, cleaned it, plugged it back in and the problem went away. I don't trust it, however, so I'm replacing it. Weird. Found one for $180, O'Riellys. I'll install it this afternoon and post results. Thanks everyone for your advice and for being a sounding board. I was a mechanic many years ago, but I retired my tools in 1984. Things have changed since then....no more carbs and points to adjust, this car doesn't even have a distributor.