Sublgcygtlmtd Posted November 27, 2017 Share Posted November 27, 2017 Hello, i was wondering if anyone might know why i drive my 2000 Legacy gt Limited for 10 - 25 minutes and when i come to a stop light the idle drops and then the car turns off. no warning lights or anything. any ideas??? Link to comment Share on other sites More sharing options...
Setnev Posted November 27, 2017 Share Posted November 27, 2017 Auto? Link to comment Share on other sites More sharing options...
Sublgcygtlmtd Posted November 28, 2017 Author Share Posted November 28, 2017 yes Link to comment Share on other sites More sharing options...
RumbleRumble Posted November 28, 2017 Share Posted November 28, 2017 fuel pump, alternator, IACV. either could be bad. Link to comment Share on other sites More sharing options...
Setnev Posted November 30, 2017 Share Posted November 30, 2017 Mine does the same thing on cold mornings (sub-40 degrees). I haven't been able to figure out the exact cause because I just figured out if I throw my transmission into neutral when it does it, it stops. When I first experienced the bucking syndrome, it was on a wet morning and I thought it was my brakes were wet and the ABS was kicking in more aggressively. I'm going to plug in my data logger now that it's starting to get back into the 30's again in the morning and see if I get some valuable readings. I'm also experiencing what feels like it bogging down in second gear or if I hit the throttle from a start with some aggression, but that happens all the time when the engine is cold. Link to comment Share on other sites More sharing options...
miniature_ninja Posted January 27, 2018 Share Posted January 27, 2018 after spending months back and forth at shops and at subaru I found out what my problem was myself Things we replaced: IAC, TPS, MAP none of those solved the issue. The problem was the idle would drop so low the car would die, sometimes the car would shudder - if I put the car from drive into nuetral the problem went away. if I touched the gas pedal to bring the idle up, the problem went away. Sometimes it would be so bad that I would have to give it a lot of gas and the car would seam like it was in "low power" mode then all the sudden take off like a bat no check engine light, smogged flawlessly, no issues other than the idle problem one day I finally just got under the car and replaced the front o2 sensor and the problem was immediately gone. when I told my local subaru specialists that had been trying to figure this problem out for months they were baffled, but tested the solution on another subaru with a similar issue and fixed that too Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted February 1, 2018 Share Posted February 1, 2018 whenever you have a car stalling when coming to a stop/ rough idle 1. check torque converter clutch operation 2. check MAP MAF Speed Density (air flow) sensor readings 3. check O2 readings Link to comment Share on other sites More sharing options...
xrayspecs Posted February 1, 2018 Share Posted February 1, 2018 have you checked to make sure the coil pack is good once the car is hot? typically a bad coil will only manifest once its hot. Link to comment Share on other sites More sharing options...
miniature_ninja Posted February 2, 2018 Share Posted February 2, 2018 whenever you have a car stalling when coming to a stop/ rough idle 1. check torque converter clutch operation 2. check MAP MAF Speed Density (air flow) sensor readings 3. check O2 readings 1: only way a regular person could do that would be voltage check - something ECU would pick up with a P0740 code. 2: car doesn't have a MAF - map won't help you 3: in my case, 02 scoped perfectly, however when replaced solved the issue. this is a very common problem on Subarus. if it were easy I think people would have done your checks by now and solved it Link to comment Share on other sites More sharing options...
Setnev Posted February 2, 2018 Share Posted February 2, 2018 after spending months back and forth at shops and at subaru I found out what my problem was myself Things we replaced: IAC, TPS, MAP none of those solved the issue. The problem was the idle would drop so low the car would die, sometimes the car would shudder - if I put the car from drive into nuetral the problem went away. if I touched the gas pedal to bring the idle up, the problem went away. Sometimes it would be so bad that I would have to give it a lot of gas and the car would seam like it was in "low power" mode then all the sudden take off like a bat no check engine light, smogged flawlessly, no issues other than the idle problem one day I finally just got under the car and replaced the front o2 sensor and the problem was immediately gone. when I told my local subaru specialists that had been trying to figure this problem out for months they were baffled, but tested the solution on another subaru with a similar issue and fixed that too I'm going to swap my front O2 sensor. Its got 158,000 miles of hard mileage on it. My symptoms are identical to what you described. Some times the car would bog so bad, other times, it takes off like a bat out of hell. I am going to order that new sensor and test this theory. Link to comment Share on other sites More sharing options...
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