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Guest Message by DevFuse

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Knock Sensor after timing belt replacement

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6 replies to this topic

#1 Mike-in-Ohio


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Posted 03 January 2006 - 08:04 PM

I having problems with my 1999 Impressa Outback Sport 2.2l engine (104K).
i've done the following over the last week and am just about at my limit.
replaced the following:
Timing Belt
Valve cover gastkets
Plug Wires
Plugs (from Bauch to NGK)
up stream O2 sensor
Down stream sensor

now the CEL show a knock sensor error or short.
car runs well at idle, slow to accelerate, bogs down on speed. cannot get the RPM above 3200 .

so i'm thinking either i've miss a tooth on the belt, which makes no sense to me since it runs well at idle. or there is something obvious that i've missed. can anyone tell me what they think? thanks

#2 blitz



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Posted 04 January 2006 - 08:22 AM

Retrace your steps carefully.

1. At what point during your servicing did the knock sensor code appear?
2. At what point did the engine begin to idle real good, but not rev above 3200?

You gotta determine whether the above problems are related to one single mistake you made, or unrelated symptoms of two separate mistakes. Maybe one is completely unrelated to anything you've done.

Check the connection to the knock sensor, maybe you knocked it off.

I know the DOHC motors can be a chore to do a timing belt on, but the SOHC aren't too bad ...just keep the marks lined up vertically. It helps a lot if you highlight the 3 marks on the block, highlight the mark on each of 2 pulleys /1 gear, and highlight the 3 marks on the belt ...all with yellow paint.

A clogged cat can limit power and RPM the way you describe.

#3 Mike-in-Ohio


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Posted 04 January 2006 - 09:29 AM

Well this morning (before work) i've taken the cover off to verify the marks. I've turn the engine by hand about 100 times (at least it felt that way) and cannot get the marks to line up as they were when i installed the belt. it looks like the marks are all one tooth to the left. however, upon digging the old belt out, it had a different part number than the one i placed upon the vehicle. the old belt is labled: 223YU26 and the new one is labled 223YU27. no I don't know the impact, i've emailed the parts supplier (btw they've been great) and have asked them to verify the numbers.

ask to the retrace of steps. once i replaced the belt all CEL where out. therefore, i can only assume that the Knock Sen was working. i've check the connection and the wires running to the sen and they look ok.

What i'm wondering now is; if the sen is working correctly then the CEL would light if there was a problem not with the sen but with engine? make sense?

#4 frag


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Posted 04 January 2006 - 04:01 PM

The first time I replaced a timing belt was on my former Loyale.
The timing was left retarded (and was later corrected at the distributor).
The symptoms were very close to yours. The engine idled perfectly (even smoother than before) but the car had no power.
Maybe your belt is one tooth off and the ECU "thinks" it's the knock sensor's fault.
Good luck!

#5 lmdew



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Posted 04 January 2006 - 04:06 PM

The belt if off, I bet! Make sure you are using the correct timing mark on the rear of the crank pulley, not the one on the front.

The same thing happened on my brothers Legacy 2.2.

Pull it back apart and reset the timing. Good Luck! Using the factory belts with the painted timing marks makes it much easier to time correctly.

#6 Mike-in-Ohio


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Posted 04 January 2006 - 07:14 PM

good suggestions. pulled the timing belt off this morning and mated the lines on the belt with the marks. however, i did use the marks on the front of the pully (crank?) is there any other marks other than the timing belt and the piston arrow? thanks mike

#7 Mike-in-Ohio


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Posted 09 January 2006 - 10:47 AM

Well I just returned from my local Subaru Dealership's Service department. yes the Knock sesor was bad, but also the Mass Airflow sensor. Lucky for me it was an "Open recall" . So thanks to all who took the time to assist me on this problem, and for all the good suggestions.


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