I just bought a 1997 Subaru Outback (2.5L) with 44K miles for $6200 two weeks ago. Great deal I thought... I had it checked by a mechanic, drove it for a while, and found it to be in great shape. Since I bought it, I have had to have it towed to a shop twice because it stalled after freeway driving and became undriveable. I could start it again but every time I tried to give it gas, it would sputter and die. If I let the engine get cold, everything returns to normal. The details to the best of my knowledge are below. I would greatly appreciate any help you could give me to diagnose the problem. Thanks in advance!
Incidents so far: The car drives fine around town. Everything seems to work well until I try to drive it at highway speeds for 10 minutes or so. The idle is good, acceleration is good, slight lifter noise but no knocking.
Incident 1: We had previously driven about 30 miles on the highway with no incident and had driven on short jaunts around town with no problems. I had been driving for twenty minutes or so and started down the freeway, after about 5 minutes the check engine light came on. I came to a stop and the engine started to idle roughly, like it was struggling to stay going. I tried to accelerate from stop and the engine died. After that I tried to start it 6 or 7 times. Each time the engine would start and idle okay, but as soon as i pressed the accelerator the engine would die. I tried gentle acceleration and revving it high in nuetral then popping it quickly into drive. Each time the engine died. I let the car sit for 30 minutes, started again, and got the same result.
I called a tow truck, which took about 45 minutes and towed it into the shop. By the time I got it into the shop, the car basically ran fine. The shop checked the OBDII codes and found: Knock Sensor and O2 Sensor. I also found there were recalls for alternator and throttle body issues, so I took it into the dealer. Neither one was defective (according to them.) After all this, the car ran perfectly again, with no check engine light, and I was able to drive around town for a few days without incident.
Incident 2: After a few days, I changed the air filter and filled up with premium gas. Everything was running perfectly for about 30 minutes. Once again the check engine light came on on the highway. I noticed that when I would slow down, I got the same chugging, low idle behavior. I continued to drive and hit some hilly sections of the highway. I noticed that when I tried to accelerate up the hills, I would push the peddle to the floor but the engine had very little power. After a few seconds, the engine would "catch" and normal power would resume. During this time, the check engine light would come on and off again eratically. A few miles later, I got off the highway and came to a stop. The engine chugged and died. I tried starting it a few times, but was unable to keep the engine going. White / Blue smoke was coming from the exhaust and there was a serious smell of gas.
I let the car sit for about an hour and tried it again...same behavior: chugging engine, white smoke, strong smell of gas. The check engine light was blinking as I tried to start it. I called another tow truck, which took about 2 hours to get into the shop. By the time I got there and started it again, there was still smoke coming from the exhaust and the check engine light was on, but the car had noticeably improved. By the time the shop looked at it, everything ran fine, there was no smoke, the check engine light was off, and there were no codes.
Has anyone seen behavior like this before? The mechanic told me flat out that he is totally confused by the problem and thinks it could be related to the Knock Sensor, Air Flow Meter, O2 sensor, or Coolant Sensor...I don't know even how to diagnose it, let alone fix it, because the only way to make it happen is to drive long enough away from home to the point that I have to tow it back.
I read online about a specific knock sensor problem that causes hesitation, and I think this could have something to do with it, but every piece of advice seems to be about Gary's Fix: a home built electrical work-around that de-sensitizes the knock sensor, but I can't find any info on it except for an outdated web page. Does anyone know what he did?
Please, please help me!!!
Incidentally, we were supposed to drive the car up to portland this weekend but we can't move, because we can't drive it more than a few miles.
THANKS