G_Mossman Posted April 25, 2019 Share Posted April 25, 2019 Car: 2006 Subaru Forester Base Model AT Two days ago I drove over to my parents' and stopped in their driveway. Turned the car off to go into their house for 5 min. Then came back out to go to work. As I am driving down the road mere blocks from their driveway, my car starts to intermittently jerk. The best way to describe the feeling is like the whole drivetrain locks for a fraction of a second making everything thump loudly. Looking back my best guess is intermittent fuel starvation, but I am open to other theories. It was happening once ever min or so, not consistently or rhythmically. I turned around and went back to my parents' house. Pulled in their driveway and tried to put the car in park. I couldn't get the gear selector to go past neutral. I didn't want to force it, so I turned the car off and then it let me put the car in park. I turn the key the rest of the way and removed it. It was idling fine in the driveway while I was sorting out the gear selector issue. I put the key back in and try to turn the car over. Nothing. No click, no weak crank. The dash and radio light up and work. I pop the hood and try to sort out what I thought to be a battery problem. I check it with a meter and it is fully charged. I clean the terminals which had very minor corrosion. It would crank now, but very weakly. I then disconnect the ground to the starter and clean it. Reattach. Now the car cranks strongly again. It struggled to get to actually start. I fiddle about for another 10-15 min looking and checking all my electrical connections. I try again and it starts up. I take it for a test spin and it starts doing the jerking thing again. I pull it into the driveway and again it wont let me put it in park while it is still running. I'm late for work, so I borrow one of their cars and decide to come back after work to diagnose. I come back 7ish hours later. It cranks right up and after a short test drive it has no issues. I check the engine codes, nothing. So I drive it home with no problem. Next day, I drive to and from work, to and from dinner, no problems. I figured it was some weird issue that sorted it self out.... Today, I again stop for a few min at my parents' on the way to work. My commute from my parents' house to work in 7ish min. through a small town. When I go to drive to work the jerking issue comes back, but much less frequent. Maybe 4 total times. As I'm driving the radio starts powering on and off. Random dash lights come on and off and the dash starts to flicker. The car is still running strong, except for the random jerks. I am taking it gentle trying to limp it to work. A mile from work the dash completely turns off: no lights, no gauge readings. The car is still running fine. Then, 1/4 of a mile from work it starts sputtering and then dies. Luckily there was a driveway just before my work parking lot I made it into. It was quite disappointing that the car didn't make it to my work's parking lot, but whatever. The car again won't let me put it in park until I turn the power off with the key. I try to crank it over immediately and it won't crank at all. I wait 5-10 min and try again. It will crank but weakly. I pop the hood and check over everything. It all looks good. I take my walk of shame to work and get some stuff done for a little while. I then go back to my car with my buddy from work's car, in case it needs a jump. It has been a little over an hour. It cranks up first try, no problem. I didn't need to jump it. I drive into work and check the engine codes. Still nothing. Have you guys ever experienced anything like this. Any suggestions on where to start? Could it be alternator? Which I replaced probably 6 months ago, but that doesn't mean it hasn't failed again. Luckily it has a lifetime warranty so I might replace it just to see if it fixes it. Could it be a short to ground? Any specific parts of the system to check that would cause all these issues? Could it be the computer? Any ways to test that? I'm open to all ideas! Thanks in advance! Grant Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted April 25, 2019 Share Posted April 25, 2019 I am not qualified to explain how/why all the weird symptoms, but the alt. would be my first 'guess'. what was the source for the alt.? typical rebuilts sold at parts stores are notoriously risky. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 25, 2019 Share Posted April 25, 2019 (edited) Loose connection when hot. Check the main output lug on the alternator since that's the most recent thing you touched. Batteries can basically die and after sitting for a while will recover - often to the point of starting the engine again - once or twice anyway if it's an engine willing and able. Also alternators can fail in such a way that they work when cold but their voltage trails off to nothing after they get hot. Your problem is consistently not there when cold. You have an electrically open circuit or high resistance when hot. Be that a mechanical connection, or an electronic component that has a circuit board or IC crack that opens when hot. And yes - parts store alternators are crap. Subaru sells reman alternators that are not junk. Get it from the dealer. GD Edited April 25, 2019 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
G_Mossman Posted April 25, 2019 Author Share Posted April 25, 2019 1 hour ago, 1 Lucky Texan said: I am not qualified to explain how/why all the weird symptoms, but the alt. would be my first 'guess'. what was the source for the alt.? typical rebuilts sold at parts stores are notoriously risky. The alternator was from Advanced Auto. I've had good luck with reman alternators, but at the same time, I've never owned a car for more than two years because I'm fickle. Haha. I'm on like Subaru number 9. But I'll start there. I'll get it replaced under warranty and then look into getting a better quality one. 3 minutes ago, GeneralDisorder said: Loose connection when hot. Check the main output lug on the alternator since that's the most recent thing you touched. Batteries can basically die and after sitting for a while will recover - often to the point of starting the engine again - once or twice anyway if it's an engine willing and able. Also alternators can fail in such a way that they work when cold but their voltage trails off to nothing after they get hot. Your problem is consistently not there when cold. You have an electrically open circuit or high resistance when hot. Be that a mechanical connection, or an electronic component that has a circuit board or IC crack that opens when hot. And yes - parts store alternators are crap. Subaru sells reman alternators that are not junk. Get it from the dealer. GD I also replace the battery in the winter. The previous one was like 10 years old and finally gave out on me. It had served me well through 3 different cars. If I replace the alternator and it doesn't fix it, could it be the battery? Could it read as having a full charge and still not give enough juice to not crank over the engine? Would temperature have anything to do with the battery working inconsistently? Thanks both of you for your quick responses. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted April 25, 2019 Share Posted April 25, 2019 on an older car, I might suspect battery cables before an otherwise new-ish battery. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 25, 2019 Share Posted April 25, 2019 You need a meter with you for when the symptoms appear. Then you can determine where you have a voltage drop, etc. Don't load the parts cannon till you have a clear diagnosis of the problem. GD Quote Link to comment Share on other sites More sharing options...
FerGloyale Posted April 25, 2019 Share Posted April 25, 2019 does the car have remote start or an aftermarket alarm? Quote Link to comment Share on other sites More sharing options...
G_Mossman Posted April 25, 2019 Author Share Posted April 25, 2019 I drove it home from work which is a fairly short commute. 5-10 min. About a mile from my house it started acting up again. All the same symptoms. I have another SG Forester that I pulled the alternator and battery out of. I first started by swapping the alternator and leaving the battery. The current battery had a full charge still. But even with the alternator swapped it won't crank strong enough to start. So I also swapped the battery too. It started right up. I drove it around for like 5-10 min. Got it plenty warm. No issues. I parked it in my driveway for 10 min. And got back in and drove around again. No issues. So at this point it's either the battery or the alternator. My plan is to drive it around for the next couple of days and make sure it wasn't a fluke. If I don't have any issues. I'll A/B test the alternator and battery and see which one causes the symptoms to return and replace that piece. Luckily these are easily accessible parts on Subarus. Thanks again for your input. I'll check back in to let you know what ends up being the culprit. 1 Quote Link to comment Share on other sites More sharing options...
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