boost Posted March 19, 2004 Share Posted March 19, 2004 Anybody know what kind of behavior a 90-94 Legacy will exhibit if it has a bad Coolant Temp Sensor? Link to comment Share on other sites More sharing options...
cookie Posted March 19, 2004 Share Posted March 19, 2004 1 It does not start when cold. 2 Is well described in the thread above. Erratic idling and running. worth your while to read the other threads on this. looks pretty easy to replace on my car. Link to comment Share on other sites More sharing options...
Tricky Posted March 19, 2004 Share Posted March 19, 2004 My car is doing the exact same thing, hard starting when its cold, and erattic idle, etc... 1992 legacy. Did this give you any codes, ? Link to comment Share on other sites More sharing options...
frag Posted March 19, 2004 Share Posted March 19, 2004 What happened in my case is (1) it would'nt start when hot (Ecu was receiving the info that the engine was cold and flooded it) (2) i also had at one point the erratic idle symptom that led to stalling and impossibility to restart. When this happens it usually possible to start the car either by waiting for the excess fuel to evaporate (at least 30 minutes) or by pushing the gas pedal to the floor while starting. This gives the engine more air and can get rid of excess fuel if the condition is not hopeless. Link to comment Share on other sites More sharing options...
Tricky Posted March 19, 2004 Share Posted March 19, 2004 sounds all too similar. However...I have replaced, several other sensors...not inccluding these and still have NO codes, but the car runs horrible....hardly back out of the garage but runs. when parked... Link to comment Share on other sites More sharing options...
boost Posted March 19, 2004 Author Share Posted March 19, 2004 Originally posted by Tricky My car is doing the exact same thing, hard starting when its cold, and erattic idle, etc... 1992 legacy. Did this give you any codes, ? Yes, the codes it spits out are: -11-Crank Angle sensor or circuit -12-Starter switch or circuit -13-Cam Position sensor or circuit -21-Coolant Temperature sensor or circuit -42-Idle swich or circuit Link to comment Share on other sites More sharing options...
mattocs Posted March 19, 2004 Share Posted March 19, 2004 Real bad gas mileage...thats what happend to me when mine went. Link to comment Share on other sites More sharing options...
boost Posted March 19, 2004 Author Share Posted March 19, 2004 Is there an easier way to test it than to put it in hot water? Link to comment Share on other sites More sharing options...
mattocs Posted March 19, 2004 Share Posted March 19, 2004 it costed me $20. I bought a new one, and installed it myself. Very easy on a 1995 Legacy. Link to comment Share on other sites More sharing options...
99obw Posted March 19, 2004 Share Posted March 19, 2004 You can get a rough idea without removing it if you can get the meter wires connected successfully. It is probably easier to just take it out. If you want to test it in the car: Let the car sit long enough to cool completely. Overnight would be best. Measure the ambient temperature. Take a resistance measurement of the sensor. Reconnect the sensor and warm the car up until the both radiator hoses are warm along their entire length. That should put your temp fairly close to the thermostat temperature. Shut it off and take another reading. From Haynes: Temp*F Ohms------------------------------------ 212 176 194 240 176 332 158 458 140 668 122 972 112 1182 104 1458 95 1800 86 2238 76 2795 68 3520 58 4450 50 5670 40 7280 32 9420 Link to comment Share on other sites More sharing options...
Legacy777 Posted March 19, 2004 Share Posted March 19, 2004 reset the ecu and then recheck codes....the likelyhood of all those things being bad is slim. Link to comment Share on other sites More sharing options...
boost Posted March 20, 2004 Author Share Posted March 20, 2004 I can unhook the battery overnight to reset the ECU right? Thanks, Shawn Link to comment Share on other sites More sharing options...
boost Posted March 20, 2004 Author Share Posted March 20, 2004 Another quick thing....The cooling fans come on immediately when the key is turned to the on position. Is this a good sign of the ECT sensor or is it the ECU going into a failure mode? Thanks in advance, Shawn Link to comment Share on other sites More sharing options...
99obw Posted March 20, 2004 Share Posted March 20, 2004 Sounds like a bad coolant temp sensor. The ECU uses the temp reading from the coolant temp sensor to determine when to turn the fan on. It sounds like the ECU thinks the engine is really warm when it is actually cold. That would explain any hard starting you may be experiencing. I would pop the connector off of the ECT with the engine cold, take a measurement, and compare it to the chart I posted. Link to comment Share on other sites More sharing options...
boost Posted March 20, 2004 Author Share Posted March 20, 2004 I didn't put the fluke meter to it yet, but I unplugged the sensor with the car running and it had no effect whatsoever. Something tells me that if the sensor was any good, it would make the car run differently if unplugged ? Shawn Link to comment Share on other sites More sharing options...
frag Posted March 20, 2004 Share Posted March 20, 2004 if the sensor was any good, it would make the car run differently if unplugged ? Good logic if you want my opinion. :wave: Link to comment Share on other sites More sharing options...
avk Posted March 20, 2004 Share Posted March 20, 2004 If the fans are on, the sensor circuit is open or shorted and most likely it's a bad sensor. Link to comment Share on other sites More sharing options...
boost Posted March 21, 2004 Author Share Posted March 21, 2004 YEP! The Coolant temp sensor was definately bad....Car fired right up after replacing it... I tested the old one for ohm's and got nothing, tested the new one and the ohm's would lower the hotter it got THANKS EVERYBODY FOR ALL YOUR AWESOME INPUT!!! Link to comment Share on other sites More sharing options...
cookie Posted March 21, 2004 Share Posted March 21, 2004 folks. Link to comment Share on other sites More sharing options...
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