Inday Posted January 7, 2005 Share Posted January 7, 2005 Hi, I got a weird problem with my Legacy 2.2 Automate (2. Gen. make '95) and no Subaru dealer has a clue so far what this might be. When the car was running for a mile or two and I stop, turn off the engine and try to start it again, it will no more start. This symptom occurs only when the machine is neither warm yet nor cold anymore. It has sparks on all 4 plugs, gas pump has pressure, the ignition works fine, still does not start anymore. Have you got any idea what is causing this behaviour? It is pretty annoying when getting stranded at a gasoline station or at a supermarket. Then I wait for 15 or 20 minutes and it starts again without a problem. If the engine is completely cold or it has already warmed up, no problem at all. No errors can be read out from the ECU afterwards. Here something about my car. It is a Subaru Legacy 2. Generation, 2.2 Automate, 120'000 km on it (about 75'000 miles), make '95, regular maintanance. Many thanks for your advices. Quote Link to comment Share on other sites More sharing options...
Nug Posted January 7, 2005 Share Posted January 7, 2005 Very rarely do I recommend this, but I would swap in another ECU. If you have spark and fuel pressure, that says that your crank and cam position sensors are fine, the ignitor is fine, coil is fine, and fuel pump relay, fuel pump is ok. Maybe, for whatever reason, the injectors are not firing. Needs to be checked with a "noid light" when it happens again. If the injectors are NOT firing, I would suspect a faulty ECU. Quote Link to comment Share on other sites More sharing options...
Inday Posted January 7, 2005 Author Share Posted January 7, 2005 I would suspect a faulty ECU.Change the ECU? But why does it not make problems when the engine is completely cold or warmed up?I rather tend to a sensor or a thermic problem in an electronic device or so. Quote Link to comment Share on other sites More sharing options...
frag Posted January 7, 2005 Share Posted January 7, 2005 I thought of a coolant temp sensor first but your symptoms are a little weird. Usually (happened to me twice with two different cars) a failing temp sensor «tells» the ECU the engine is cold when in fact it is hot and ECU sends to much gas thus flooding the engine. I would be almost certain of a coolant temp sensor if your could'nt start anytime the engine is warm or at operating temp. Butmaybe your sensor sends a wrong message only when the engine is warm and resume proper function when the engine reaches operating temp. Nevertheless, the fact that waiting for some time is sufficient to have the engine start again points to a flodded engine situation. Next time this happens, the minute you see the car is not going to start (dont wait to long) push the gas pedal to the floor and keep trying to start. This will give the engine more air and might very well ofset the excess gas. If your engine then starts, i would bet it is the coolant temp sensor. Hope that helps. Quote Link to comment Share on other sites More sharing options...
coloradosubarules Posted January 7, 2005 Share Posted January 7, 2005 I had a problem similar to this in on a previous vehicle. When the starter was first warmed up it wouldn't crank due to bad bushings. Replaced starter and problem was fixed. Notice he doesn't say that it turns over but will not fire. Maybe someone should ask before jumping to conclusions. So....Does the engine turn over (crank)???? Quote Link to comment Share on other sites More sharing options...
frag Posted January 7, 2005 Share Posted January 7, 2005 I had a problem similar to this in on a previous vehicle. When the starter was first warmed up it wouldn't crank due to bad bushings. Replaced starter and problem was fixed. Notice he doesn't say that it turns over but will not fire. Maybe someone should ask before jumping to conclusions. So....Does the engine turn over (crank)???? First poster says he has spark when his engine will not start. That's how I concluded that his engine was turning over but not catching. Sherlock Holmes Quote Link to comment Share on other sites More sharing options...
ron917 Posted January 7, 2005 Share Posted January 7, 2005 I haven't had this problem on my Subaru, but... The symptoms sound very similar to crank/cam position sensor problems I've seen on other vehicles. The CPS failure mode tends to be intermitant and temperature related, with a warm (not cold or hot) no-start. Also, in the other vehicles, the ECU did not throw a code. The only way I could prove the CPS was at fault was with an oscilloscope or voltmeter - when the car wouldn't start, there was no signal, otherwise, it was fine. I don't know about your particular Subaru ECU, but many ECUs will run the fuel pump for a time while cranking, regardless of sensor signals. So, the fact that you have fuel pressure doesn't rule out sensor issues. DO NOT pay for a new ECU without absolute proof that it is the problem. ECUs are expensive but easy to change - in other words, high profit margins for the shop. Try to find a known good one to borrow for a while. These types of problem require patience, the shop manual, and good diagnostic skills. It's a pain to find the problem, but once found it is usually a simple fix - a sensor, wire or connector is almost always the culprit. Quote Link to comment Share on other sites More sharing options...
frag Posted January 7, 2005 Share Posted January 7, 2005 If pushing the pedal to the floor does'nt start your engine, ron's analysis makes a lot of sense. Quote Link to comment Share on other sites More sharing options...
Setright Posted January 7, 2005 Share Posted January 7, 2005 Had a colleague with a similar problem on a Renault Megane. I once witnessed the no start situation, and tried opening the throttle from under the hood while he cranked it, but still didn't start. Unfortunately, the Megane owner is not technically minded and I he has no real understanding of what the dealer did to fix his car. Other than "they replaced something". I am sure it wasn't the ECU. I would start by disconnecting the crank postion sensor and cleaning the terminals. Re-install and try again. If that doesn't help, replace the crank sensor itself. It's the most likely cause. And it's easy to replace too. Quote Link to comment Share on other sites More sharing options...
Nug Posted January 7, 2005 Share Posted January 7, 2005 Sometimes, the ecu will get a crack in a board. Temperature fluctuations in the board cause it to flex, momentarily making contact. This is rare, however, if for whatever reason you had a spare lying about, you could swap it in and see what happens. Quote Link to comment Share on other sites More sharing options...
Nug Posted January 7, 2005 Share Posted January 7, 2005 OK, ok, you need to check out a lot of other stuff before you get to the ecu. But if you had spark and no injection at the same time, I'd be leary. Edit: Check the crankshaft and camshaft position sensors and their related circuitry very carefully. Also, ecu power supply. Quote Link to comment Share on other sites More sharing options...
Inday Posted January 8, 2005 Author Share Posted January 8, 2005 Thanks for all this information. Yes, I also floored it for about 30 to 40 seconds while engine is turning with starter, but still does not start. That was the first thing my dealer told me to do. When it starts after a few minutes it does not sound as if it was flooded, no strange sounds, no smoke, nothing, it just runs fine again. I like to mention that it was never at the Dealer's while this problem happened (arrived there when engine was warm, so could'nt reproduce it), so I meant there were no errors from the ECU afterwards because the ECU is resetting onces the error does not occur anymore. I really must leave it at the Dealer's once and reproduce it there while it was there over night. Maybe an error is issued when the problem can be reproduced? It is just a pain because the dealer is not just around the corner, it means go there with two cars, leave the Subaru there and pick it up again the next day with two cars again. If you do that very often it sucks. I read somewhere that I can connect two black cables under the dashboard and read out the signal by myself by counting the code - what was it? - lights or sounds. Where exactly can "I" find these two black cables and when I succeed to do so has anybody of you got an idea what that error code means then? Inday Quote Link to comment Share on other sites More sharing options...
Gnuman Posted January 8, 2005 Share Posted January 8, 2005 I read somewhere that I can connect two black cables under the dashboard and read out the signal by myself by counting the code - what was it? - lights or sounds. Where exactly can "I" find these two black cables and when I succeed to do so has anybody of you got an idea what that error code means then? Inday They are between the steering column and the console, often just under the trim that goes around the bottom of the column (sometimes just clear of it). when you connect the cables (or disconnect them if they are connected), you will get a series of long and short flashes of the Check Engine Light (CEL). The long flashes are the tens digits (count them to get the number), and the short ones are the ones digits. This will only happen, however, if there is a condition that turns on the CEL in the first place. If there is no CEL, then the Engine Control Unit is not detecting a problem, and this procedure is of little use to you. (the the best of my knoledge, doen anyone know any differently?) Quote Link to comment Share on other sites More sharing options...
89Ru Posted January 10, 2005 Share Posted January 10, 2005 '95 legacy has OBD II (verify sticker under hood). Subaru adopted the standard a year before they had to. You'll need a scan tool to read the codes. Search this board for scan tools, a variety of features (and prices!) are available. Codes are stored for 40 warmup cycles if CEL goes off so you don't need to be at the dealer when the problem occurs. Quote Link to comment Share on other sites More sharing options...
Inday Posted January 7, 2006 Author Share Posted January 7, 2006 By chance I have been at a car electrician yesterday evening when the car didn't like to start again. So the guy examined it carefully and then suspected a faulty EFI-ECU might be the cause (as @Nug correctly mentioned already last year!). The car does not inject gas while cranking. Leave it for another 20 minutes or so and it starts fine again. So my next try will be to find a used EFI-ECU since new ones are very very costly. I will keep you up to date whether it solved my problem or not. Inday Quote Link to comment Share on other sites More sharing options...
Overthehill Posted January 7, 2006 Share Posted January 7, 2006 I 'm not a mechnanic but had the same problem with my 86 944. After washing the engine compartment while it was running ( duh) the problem appeared. After running about 1 to 5 minutes the car would not start again when shut off. Cranked but no start. After having it towed ( 3 times I might add ) I finaliy figured out after 10 or 15 minutes it would start again. Needless to say since Porche could not duplicate the problem by the time they got the car they could not find it. Intermitten problems are a $%^. Anyway they eventually replaced the computer controll unit and the car never had the problem again. Cost me a bundle for my own stupidity! Hope this helps. Overthehill Hi, I got a weird problem with my Legacy 2.2 Automate (2. Gen. make '95) and no Subaru dealer has a clue so far what this might be. When the car was running for a mile or two and I stop, turn off the engine and try to start it again, it will no more start. This symptom occurs only when the machine is neither warm yet nor cold anymore. It has sparks on all 4 plugs, gas pump has pressure, the ignition works fine, still does not start anymore. Have you got any idea what is causing this behaviour? It is pretty annoying when getting stranded at a gasoline station or at a supermarket. Then I wait for 15 or 20 minutes and it starts again without a problem. If the engine is completely cold or it has already warmed up, no problem at all. No errors can be read out from the ECU afterwards. Here something about my car. It is a Subaru Legacy 2. Generation, 2.2 Automate, 120'000 km on it (about 75'000 miles), make '95, regular maintanance. Many thanks for your advices. Quote Link to comment Share on other sites More sharing options...
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