Power Loss at low rpm...knock sensor?

[ZZZ]

1999 impreza outback sport...Check engine light is on and the code is for the knock sensor. When going up hills, or off the bat in 1st the car will stutter and/or lose power. For example a small hill in 4th gear at low rpm will make the car stutter and force me to downshift due to the lack of power. When this happens and I don't downshift the check engine light will flash until I do. I feel like this must be a telltale sign that I don't know about. Could replacing the knock sensor really solve this problem?

 

Live here in a ski town and trying to avoid getting bent over by the inflated local mechanic, any help is much appreciated.

 

thanks!!

[Fairtax4me]

The knock sensor is famous for causing all sorts of trouble on Subarus. If you have a code for it, it probably needs to be replaced. Search for Knock Sensor here on the forums for directions on how to do it. There may be a link in the "similar threads" at the bottom of the page here.

[Qman]

Knock sensors are designed to pull timing at upper rpm's to minimize detonation. Chances are slim that it will cause low rpm problems.

[Fairtax4me]

Knock sensors are designed to pull timing at upper rpm's to minimize detonation. Chances are slim that it will cause low rpm problems.

 

When working properly, absolutely. But there are plenty of threads here documenting drivability problems at all RPM due to faulty knock sensor.

[zacyork]

i have heard of people replacing the knock sensor on these years and it still going off. something about excessive vibration where it mounts. i heard there is a port just above where it is originally located that people use instead and that gets rid of the code. there is also threads out there talking about it being an ecu problem.

[Rooster2]

Suggest you go to an auto parts store, one of the chain stores like Autozone, or Advance. The counter guy will read the code with his instrument, and tell you what code is setting off your check engine light. There is no cost for this service. If it is a bad knock sensor, or something else, well then you are at the right store at the right time to buy parts to fix the problem.

 

Changing a knock sensor is relatively easy, just a little awkward to find, and get a wrench on to remove. Check the search archives on this forum to see pixs and write ups on how to do it.

[ZZZ]

Suggest you go to an auto parts store, one of the chain stores like Autozone, or Advance. The counter guy will read the code with his instrument, and tell you what code is setting off your check engine light. There is no cost for this service. If it is a bad knock sensor, or something else, well then you are at the right store at the right time to buy parts to fix the problem.

 

Changing a knock sensor is relatively easy, just a little awkward to find, and get a wrench on to remove. Check the search archives on this forum to see pixs and write ups on how to do it.

 

The check engine light reads the code for a bad knock sensor. I had trouble believing this to be the problem as was said earlier, usually high rpm is where you would notice a difference. I am going to try a new knock sensor anyways I think, just wondering if anyone had a similiar experience, or if there are any other ideas with what may be causing the loss in power. New fuel/air filter made no difference.

 

Another random question for anyone who might have a second to answer. Is it possible for the lowbeam to be out, but high beam still function on the model subie? Same bulb for both....

 

Happy to have found this forum....Is there a way to get around the 3 character search function requirement?

 

 

And yes. I promise i'll ease up the excessive questions.

Edited November 10, 2010 by ZZZ

[johnceggleston]

Another random question for anyone who might have a second to answer. Is it possible for the lowbeam to be out, but high beam still function on the model subie? Same bulb for both....

 

Happy to have found this forum....Is there a way to get around the 3 character search function requirement?

 

 

And yes. I promise i'll ease up the excessive questions.

 

yes, the low beam can go and the high beam still be good. single bulb ~5$, i think.

 

if searching EGR add a *, EGR*.

 

some one has this quote in their signature, "there is no such thing as a dumb question, but they are easier to answer."

[ZZZ]

some one has this quote in their signature, "there is no such thing as a dumb question, but they are easier to answer."

 

ha! dead on!

 

Thanks for the answers, much appreciated.

 

Another dumb question. Can't seem to find a good how too for the knock sensor. Any links?

[Olnick]

Can't seem to find a good how too for the knock sensor.

 

 

A quick search (Tah-Dah!) turned up numerous posts. Here's one that may help.

 

http://www.ultimatesubaru.org/forum/showthread.php?t=86018&highlight=knock+sensor

 

Good luck.

[ZZZ]

thanks for all the responses guys.

 

Couple other points that might help me diagnose this....

 

Engine hiccups while idling at startup.

Car almost wants to stall while letting the clutch out in first....recently replaced clutch...hesitation?

CEL light blinks when the car bucks from being in too high gear, low rpms...

 

any other thoughts?

[KZCool]

Did you ever get this figured out? I'm having kind of a similar problem with my 99 OBS AT. It seems to be common from my searches but no one finishes their forums with solutions lol