nutt7 Posted July 8, 2004 Share Posted July 8, 2004 ea82t- I have a thermosensor trouble code on the ecu...sometimes, it seems like my car runs hotter and more sluggish on some days, with similar weather conditions and driving conditions. Sometimes startup idle is sluggish too. Sound like a thermosensor could cause this? What size socket do I need to get it out? Its tough to fit something over it due to the plastic connector that seems wider than the bolt head. thanks Link to comment Share on other sites More sharing options...
Dr. RX Posted July 9, 2004 Share Posted July 9, 2004 Gee, let me see, thermosensor, could that be a sensor that senses the temperature? Would the ability to sense temperature cause an engine to heat up? UUMMM, why does the sensor need to sense the temperature? Maybe to adjust the fuel injection to adjust for higher temperatures. So if it adjusts for higher temperatures, would it cause higher temperatures? I think not, maybe the sensor going bad is the result of something else causing the temperature to get too hot causing the thermosensor to fail. What do you think? Link to comment Share on other sites More sharing options...
calebz Posted July 9, 2004 Share Posted July 9, 2004 Corky, don't be an rump roast. Its fabulous that you understand the function of the ECUs Coolant temp sensor. Thats no reason to be condescending to those that don't. The Thermosensor for the ECU(I assume you are getting a code 21) Will help the computer determine how much fuel the motor needs. That will change how it the motor runs if the sensor is not functioning correctly. It could make the car run lean, which in my experience with subarus can cause the car to run a little warmer than usual. Chances are that if you are running significantly hotter than you should be, theres another culprit. I have gotten a code for the Coolant temp sensor a few times. I Have been able to remedy it every time by cleaning the contacts on the sensor and the plug.. They get kinda gross after a while. Link to comment Share on other sites More sharing options...
ByTheSea Posted July 9, 2004 Share Posted July 9, 2004 Gee, let me see, thermosensor, could that be a sensor that senses the temperature? Would the ability to sense temperature cause an engine to heat up? UUMMM, why does the sensor need to sense the temperature? Maybe to adjust the fuel injection to adjust for higher temperatures. So if it adjusts for higher temperatures, would it cause higher temperatures? I think not, maybe the sensor going bad is the result of something else causing the temperature to get too hot causing the thermosensor to fail. What do you think? If it's the same set-up(relatively) as the NA motor then doesn't the sensor tell the ecu the motors operating temp to control mixture ratios? Mine failed and was showing resistance values to the ecu that suggested the motor was encased in a block of ice when it was at full operating temp. Caused some serious mileage issues but honestly I don't know whether the super fat mixture caused the motor to run hotter. Could a failed thermosensor be caused by excess temps,,,how hot can the water in a 82T get before things go pop. Probably not much hotter than the sensors meant to run at routinely but again I'm no expert on turbo motors. Since the ecu is meant to see the correct resistance value from that sensor to determine mixture ratios it seems like a starting point would be to test the sensor and replace it if it's bad. Ignoring a known fault makes it hard to rule it out as the cause of other problems. Link to comment Share on other sites More sharing options...
nutt7 Posted July 9, 2004 Author Share Posted July 9, 2004 Thanks Corky, you have successfully made me cry. I now realize my place in this world as a mere simpleton...I was thinking along the lines of maybe the sensor was causing a lean mixture as calebz said...the car is not overheating, it runs warmer than normal on occasion, about 15deg above the usual, and this is accompanied by a noticably more sluggish engine. My question is now restated: Could a false signal from a bad thermosensor cause a lean mixture? If so, could it be lean enough to cause the engine to run noticably warmer? This is my only subaru and I have had it for 5 months so please bear with me as I try to understand it better. calebz, the connectors do look a bit nasty, what can I use to clean them? Also, what size socket do I need to remove it so I can test/clean it? I was having a hard time fiiting one on there. bythesea, thanks for your input...I will test the resistances once I remove the sensor thanks, eric Link to comment Share on other sites More sharing options...
calebz Posted July 10, 2004 Share Posted July 10, 2004 to clean it, use electrical contact cleaner.. available at the parts stor for about $3-4.. comes in a can just like carb cleaner. Don't pull it out unless its bad. I know its a pain to get to, but test it in place if you can. As far as the socket goes, the last time I had one out, the whole manifold was off and I just used a wrench.. don't rightly remember what size though. My suggestion would be to clean it, clean the plug, slap on some dielectric grease( $.99 for a packet at the parts store). reset the codes and see if theres any difference. Now to address your temp issue. My opinion is that the coolant temp sensor(ECU), while nasty and throwing a code, is probably not the issue. I would be looking at the thermoswitch for the fan.. for some reason they always seem to come on a little late for my comfort. Or possibly a sticking thermostat. If you replace the Tstat, get one from subaru. The parts store ones suck. Link to comment Share on other sites More sharing options...
Turbone Posted July 10, 2004 Share Posted July 10, 2004 Or it could be something even simpler and not related to the sensor. Have you checked the timing lately? It cant hurt to check, and these are classic symptoms. And definatly clean the terminals, it will probably get rid of the trouble code. And Corky, sometimes............ Link to comment Share on other sites More sharing options...
Cougar Posted July 10, 2004 Share Posted July 10, 2004 Here is a list of temperature vs. resistance readings for the sensor from the service manual. If you want to measure the resistance of the sensor on the wire going to the ECU the wire color is white/black, on pin 9 of the ECU connector. Here are the specs: Temp.---- Ohms deg.F 248------ 14.9-17.3 212------ 26.2-29.3 176------ 47.5-56.8 122------133.9-178.9 I suspect you have a poor connection and just cleaning things will fix this. If the sensor was bad, I don't think it would be intermitant, but it is possible. As was suggested earlier I would not remove the sensor until it is proven to be faulty. You may want to remove the connector going to the ECU if you take your reading at that point so you don't have the rest of the circuit possibly changing your reading. If you take it at the sensor then just remove the wire to it. I like the idea of taking the measurement at the ECU as it will include all the wiring to the sensor in case there is a problem there. Link to comment Share on other sites More sharing options...
nutt7 Posted July 18, 2004 Author Share Posted July 18, 2004 Cougar, I think you gave me the info for the sender not the sensor. I tested the sensor and from the crappy description my haynes gives me, it reads right on. I cleaned the terminals of the sensor and the plug with electric contact cleaner and coated them with dielectric grease. It runs much better now, hot or cold, with intermittent flaking out, (the clip for the sensor is broken, need to replace) ...thanks guys! Link to comment Share on other sites More sharing options...
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