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Engine drops momentarily '92 Legacy AT


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About a week ago my car started doing something funny. I was driving down the road and it was like the engine cut out briefly. It has begun doing it more frequently. To me it feels like ignition is going away briefly on all cylinders. It generally does it when I am cruising. It hasn't done it under heavy power. The worst time it did it the check engine light came on momentarily.

There are two other things that I am experiencing that I will relay in case they are related.

Has real trouble starting below 32 deg. Have replaced the Coil Pack and the engine temp sensor but it didn't help. Generally warming up the engine compartment allows it to start. It acts mostly like it has no spark. Just cranks with no signs of life. Modulating the pedal a lot gets it to pop a little. (I know it is Injected) I haven't been able to identify any specific part that needs warmed in order to get it to start.

My tranny has also been acting up a little. Long gaps between shifts causing revs when I am pushing it before the torque converter grabs it. I checked the fluid and it looked okay and didn't smell burned.

 

Thanks,

Stephen

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Hi Stephen,

 

I had a similar issue with the Legacy back in late 1999, early 2000. I would be driving along and the car would lose power. If I put the transmission in neutral I could bring it back most of the time. If the rpm was low, the engine would die.

 

The problem turned out to be the MAF sensor. Did you pull the codes from the ECU to see what was stored? If not, I'd suggest doing that. Instructions on how to pull the codes are on my site.

 

http://www.surrealmirage.com/subaru/engine.html

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Okay, I got the codes and they are listed in the order that it displayed them:

 

31 Throttle Sensor

32 Oxygen Sensor

13 Cam Angle Sensor

 

"A faulty TPS can cause driveability problems such as

hesitation, stalling, an erratic idle, pinging (spark

knock), no torque converter lockup, hard starting, an

intermittent check engine light while driving, poor

fuel economy, and generally poor engine performance." (Wells Counterpoint Volume 2, Issue 1)

 

The TPS sounds like a likely candidate. Might fix my hard starting problem too as well as explaining why the Torque Converter unlocks even if it didn't really loose any speed. So, with it being the first code given does that make it the oldest or most recent code?

 

Thanks

Stephen

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I disconnected the battery for a minutes as the Haynes manual says that will clear the codes. Not sure. When I turned the key back on, the codes were still there so either it didn't clear or they are the kind of codes that it senses immediately on power up.

 

Stephen

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You can also pull fuse 14 (EGI/TCU). The battery or the fuse need to be disconnected for at least an hour.

 

Here are instructions for testing the TPS.

 

http://main.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing1.jpg

http://main.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing2.jpg

http://main.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing3.jpg

 

The third scan is really the only adjustment you can do on the TPS. Most TPS's are not dead on for the other measurements, but as long as they're close, it's ok. The third scan for setting the idle switch is what you should verify and adjust if necessary assuming the other tests are ok.

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I tested the throttle closed switch part of the TPS and it checked out. Heard from a long time used Subaru dealer/mechanic/shop owner that the Cam Angle Sensor is most likely my problem. Getting a used one this weekend. BTW if anyone needs used Subi parts in the NW, lookup Mountain Tech Subaru in Oregon City, OR. They have a warehouse of parts as they part out DOAs before sending them to the crusher. My dad's '99 Outback is getting a new hood painted to match from them after a furry four legged creature decided to act like a Deer in the headlights. Oh, yeah, it was a deer. Typical.

 

Stephen

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  • 1 year later...

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