Blondie521 Posted December 28, 2007 Share Posted December 28, 2007 Ok, guys I need some information! My car is dying and ive been told that it is the ecu that is going bad. It continually wont start and i only get 180 miles to a full tank of gas. I have changed the fuel filter, spark plugs and wires, and still no performance. I need to know how to change the ecu and where it is. Everybody keeps saying under the right side of the dash but i just went and looked and there are too many wires to tell. So if you have some information to steer me in the right direction that would be great! Thanks Ahead of Time! Quote Link to comment Share on other sites More sharing options...
jon38iowa Posted December 28, 2007 Share Posted December 28, 2007 Ok, guys I need some information! My car is dying and ive been told that it is the ecu that is going bad. It continually wont start and i only get 180 miles to a full tank of gas. I have changed the fuel filter, spark plugs and wires, and still no performance. I need to know how to change the ecu and where it is. Everybody keeps saying under the right side of the dash but i just went and looked and there are too many wires to tell. So if you have some information to steer me in the right direction that would be great! Thanks Ahead of Time! What year and Model? Quote Link to comment Share on other sites More sharing options...
Blondie521 Posted December 28, 2007 Author Share Posted December 28, 2007 What year and Model? it is a 96 legacy L 2.2 liter awd Quote Link to comment Share on other sites More sharing options...
WAWalker Posted December 28, 2007 Share Posted December 28, 2007 Subaru ECU's rarely fail. What is the reasoning behind the recommendation to replace the ECU? Was anything eles checked other than tune-up items before coming to the conclusion that the ECU is bad. How many miles on the car? Is the check engine light on while driving? Define "still no performance". No better milage, or is there an actual drivability problem? Have you cauclutaed actual fuel milage, keeping track of how many gallons you put in at the pump, and mileage between tanks, averaged over 3-4 fill ups? Quote Link to comment Share on other sites More sharing options...
EVOthis Posted December 28, 2007 Share Posted December 28, 2007 the ECU is on the passanger side, under the carpet, directly below the glove box......just pull back the carpet and you will see like an access shield protecting the ECU.... Quote Link to comment Share on other sites More sharing options...
frag Posted December 28, 2007 Share Posted December 28, 2007 Ok, guys I need some information! My car is dying and ive been told that it is the ecu that is going bad. It continually wont start and i only get 180 miles to a full tank of gas. I have changed the fuel filter, spark plugs and wires, and still no performance. I need to know how to change the ecu and where it is. Everybody keeps saying under the right side of the dash but i just went and looked and there are too many wires to tell. So if you have some information to steer me in the right direction that would be great! Thanks Ahead of Time! It's not inside the dash but lower. Remove the carpet on the pass side where it goes up the fire wall. You'll probably have to remove the glove box to have complete access to it. There's a metal cover there held by screws. Remove and the ECU is underneath. Quote Link to comment Share on other sites More sharing options...
nipper Posted December 28, 2007 Share Posted December 28, 2007 Lets see what the codes are first before you start doing brain transplants. There are many other things that can be causing this. Also if it IS the ecu, you want to see whats going on before you replace it. If there is a wiring issue someplace else you will just blow the replacment. Get to a autzone or some such thing and get the codes read for free. Gas mileage can be a good old fashioned tune up, a bad o2 sensor, a bad engine temp sensor, bad thermostat just to name a few. nipper Quote Link to comment Share on other sites More sharing options...
Blondie521 Posted December 28, 2007 Author Share Posted December 28, 2007 Subaru ECU's rarely fail. What is the reasoning behind the recommendation to replace the ECU? Was anything eles checked other than tune-up items before coming to the conclusion that the ECU is bad. How many miles on the car? Is the check engine light on while driving? Define "still no performance". No better milage, or is there an actual drivability problem? Have you cauclutaed actual fuel milage, keeping track of how many gallons you put in at the pump, and mileage between tanks, averaged over 3-4 fill ups? The car has 173K miles on it, yes the check engine light comes on periodically, and stays on for a few hours to a few days, after the plugs and wires were changed the car would not start again so it was taken to someone who could put it on the computer and that is what came up for the codes, something about it was almost all the way bad. I have been having the low gas mileage problem for about six months, thats when i changed the fuel filter, didnt get any better, then it started not starting, thats when i changed the plugs and wires over this past weekend. it wouldnt start on me again today. i think it has gone into the fail safe mode cause it has no get up and go and if i do try to get over fifty its like i dont even have my foot on the gas, almost like its in neutral, i reset the tach every time i fill my tank and have not seen 200 miles or more in a full tank in a very long time. usually ranges between 180 and 187 per full tank. do you have any other suggestions about what could be wrong before i climb into this mess? I'm a girl who doesn't mind getting dirty to fix it i would just rather not fix something that may not be broken and working on electrical stuff in the car scares me any way! Thank you for taking the time to read my book lol! Quote Link to comment Share on other sites More sharing options...
nipper Posted December 28, 2007 Share Posted December 28, 2007 The car has 173K miles on it, yes the check engine light comes on periodically, and stays on for a few hours to a few days, after the plugs and wires were changed the car would not start again so it was taken to someone who could put it on the computer and that is what came up for the codes, something about it was almost all the way bad. I have been having the low gas mileage problem for about six months, thats when i changed the fuel filter, didnt get any better, then it started not starting, thats when i changed the plugs and wires over this past weekend. it wouldnt start on me again today. i think it has gone into the fail safe mode cause it has no get up and go and if i do try to get over fifty its like i dont even have my foot on the gas, almost like its in neutral, i reset the tach every time i fill my tank and have not seen 200 miles or more in a full tank in a very long time. usually ranges between 180 and 187 per full tank. do you have any other suggestions about what could be wrong before i climb into this mess? I'm a girl who doesn't mind getting dirty to fix it i would just rather not fix something that may not be broken and working on electrical stuff in the car scares me any way! Thank you for taking the time to read my book lol! Ok you have been throwing money at the car without really diagnosing the issue. I can come up with any number if items, including a coolant temp sensor that can do this. Get the codes read. Disconnect the battery for an hour, and drive the car. When the CEL comes on again, get them read again (i want to see what the differnces are) and tell us what they are. I dont think there is anything wrong with the ECU, it sounds alot like a bad temp sensor. The car cant tell that it is warmed up. nipper Quote Link to comment Share on other sites More sharing options...
WAWalker Posted December 28, 2007 Share Posted December 28, 2007 First, there is no code for a bad ECU. It can tell if when there is a malfunction with other sensors, but it can not tell you that it is bad. Take it somewere eles and get the codes pulled. Write down the code numbers. I'm thinking there is a very good possibility that you have a bad coolant temp sensor, possibly a bad knock sensor. Both will definetly affect fuel mileage to an extent. The coolant temp sensor can cause a no start. If the coolant temp sensor is showing a low coolant temp reading all the time the engine will run rich. If run rich long enough, the catyletic converter can melt, restricting exhaust flow, and cause major loss in power. But there are many things it could be, and without knowing what codes are being thrown, we are just guessing. Quote Link to comment Share on other sites More sharing options...
Skip Posted December 28, 2007 Share Posted December 28, 2007 Here is a one simple test for the Coolant Temp Sensor (CTS). Do the electric radiator fans come on as soon as you start the car? If the sensor is bad and the ECU triggers this fail safe we are starting to get somewhere. Hope this helps. The other boyz are going to poo poo this for one reason or another but it is one way to know the CTS is bad. Quote Link to comment Share on other sites More sharing options...
Blondie521 Posted December 28, 2007 Author Share Posted December 28, 2007 Ok you have been throwing money at the car without really diagnosing the issue. I can come up with any number if items, including a coolant temp sensor that can do this. Get the codes read. Disconnect the battery for an hour, and drive the car. When the CEL comes on again, get them read again (i want to see what the differnces are) and tell us what they are. I dont think there is anything wrong with the ECU, it sounds alot like a bad temp sensor. The car cant tell that it is warmed up. nipper Thank you so much for your help, i will do as you say probably tomorrow and will post the results! i look forward to getting more of your input! Thanks Again!! Blondie Quote Link to comment Share on other sites More sharing options...
WAWalker Posted December 28, 2007 Share Posted December 28, 2007 Here is a one simple test for the Coolant Temp Sensor (CTS). Do the electric radiator fans come on as soon as you start the car? If the sensor is bad and the ECU triggers this fail safe we are starting to get somewhere. Hope this helps. The other boyz are going to poo poo this for one reason or another but it is one way to know the CTS is bad. No poo poo:grin: This is a good easy test. Be sure the A/C or defrost are not on though, as the cooling fans will run KOEO (key on engine off) if either A/C or defrost are on. Even if you forget and leave the CTS unpluged, and the ECU is seeing a reading of -51 deg F, it will turn the cooling fans on. Been there done that. Quote Link to comment Share on other sites More sharing options...
Blondie521 Posted December 28, 2007 Author Share Posted December 28, 2007 No poo poo:grin: This is a good easy test. Be sure the A/C or defrost are not on though, as the cooling fans will run KOEO (key on engine off) if either A/C or defrost are on. Even if you forget and leave the CTS unpluged, and the ECU is seeing a reading of -51 deg F, it will turn the cooling fans on. Been there done that. Ok, maybe there is more to the whole thing, it does seem to act worse since i have been having to run my defrost more often, and today when it wouldnt start all i did was turn the switch to turn the headlights off before i tried starting it again and it started right up, but would the sensor your talking about give me extremely bad gas mileage as well? Quote Link to comment Share on other sites More sharing options...
WAWalker Posted December 28, 2007 Share Posted December 28, 2007 Ok, maybe there is more to the whole thing, it does seem to act worse since i have been having to run my defrost more often, I was just saying to preform the test that skip mentioned the defrost needs to be turned off. In fact on your car, if you just turn the fan switch to "0", all the heater/A/C functions will turn off. Then if you turn the key on without starting the engine, the cooling fans should not run. If they do that points to a problem with the coolant temp sensor cuircut. and today when it wouldnt start all i did was turn the switch to turn the headlights off before i tried starting it again and it started right up, but would the sensor your talking about give me extremely bad gas mileage as well? When you say it won't start, is it a crank but no start? Or is it a no crank. Yes, the coolant temp sensor can cause extremely bad gas mileage, and drivability. A cold engine needs more fuel to start and run, as engine temp increases the amount of fuel can be decreased. This is the function of the engine coolant temp sensor. To monitor engine temp, report to the ECU, so the ECU can adjust fuel injector pulse widith accordingly. (It is not the same sensor as for your temp gage). I very often see coolant temp sensors fail and give a reading of -44 deg F. In this case the ECU gives the engine way more fuel than is needed. A lot of the time this will cause a crank but no start condition due to flooding. If the temp reading from the coolant temp sensor stays fixed that low while driving, it will cause poor fuel milage, and drivability problems. Oh, and as I said earlier, can also lead to a melt down of the catylic converter. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.