Would engine run great if Timing Belt 1 tooth off?
 

Earthworm brought up a good point, both my left side O2 and Knock sensors are posting codes, could my cam on the left be 1 tooth out? and if so, would the car run as good as every?

Short answer.... no. And at 200+ miles it should be anyway if you haven't already. Seals too.

Another thing to keep in mind is the wiring for the left O2 and knock sensor are VERY close to eachother, they even share a clip and loom I think. So could be a wiring issue too.

-edit-
Actually, now that I think about it that may not be the knock sensor on that loom.... I'll have to go look sometime

There was some discussion that it would actually improve power by doing this. It was in a thread about cams, though at this point the technical details are beyond me... for now.

http://www.subaru-svx.net/forum/showthread.php?t=30498

Thx SpeedKlix, I'm not totally convinced I have a bad O2 or Knock sensor because as you describe, they are close to each other.
And Nemesis, great read on that thread on advancing the timing, and I agree, I do believe advancement of 1 tooth can improve performance, but I'm only suspecting one side, and if I think about it I would suspect a 1 tooth slip in the opposite direction, so by counts on that thread, an 8 degree retard on my left side.

So now is my delemna, since a Knock Sensor is $158CDN up here(from the dealer)
1)Can I easily test to knock sensor to ensure its toast??
2)or should I persue the verification of the timing on the left cam? Belt was changed around either 140 or 160k miles, can't remember but I do have a log of all mainitance. Thx John H.

I'm going to try and search the forum for a test proceedure, or could just do a basic resistance test and compare the 2 knock sensors?

Many times a Subaru will be one tooth off only on one cam. Makes it very difficult to diagnose as the engine doesn't run very bad, if at all noticeable. I highly doubt that a belt being off one or thirty teeth would cause a knock sensor code - read on:

The thing to think about in this situation is how does the ECU determine that either sensor (or its respective circuitry) is bad. The ECU expects to 'see' noise from the knock sensor, whether or not there is knock present. Specfic frequencies are watched for, as they have been determined by engineers to represent actual engine knock. So... if the ECU doesn't see any response or the response never varies (in a manner of speaking), or the voltage is above/below standards (such as shorted to battery voltage) it will deduce that the sensor or its circuitry is faulty.

How does it determine if an O2 sensor is bad? Several different ways - first it expects to see a voltage between 0 & 1 volt within xx amount of time after the engine has started. It also expects that voltage to begin crossing back and forth across the threshold of around .45v x times/minute within xx amount of time after the engine has started. It doesn't expect to see voltage above 1.1v.

The ECU knows the engine is running because it sees an 'appropriate' signal from the crank sensor, and may also check in with other sensors to verify, such as the cam sensor, MAF, etc.

p.s. When posting a code in a post it would be helpful to post the code description verbatim. I don't want to leave the post to go look it up, as I'm certain many others don't either. It would be nice if someone would find a way to make this a forum header/notice.

From the FSM, here are the values for checking the knock sensor: Found in the FSM Section 2-7, pg. 73-74

Checking Input signal for ECU:

...Turn ignition to "ON"
...Check voltage between ECU connector and body.

...Connector & Terminal/Specified voltage
...(B61) No.6—body/ 3–4V


Checking Knock Sensor 2
...Remove collector
...Disconnect connector from knock sensor 2
...Measure resistance between knock sensor connector and body.

...Connector & Terminal/ Specified resistance
...(E19) No.1—Body/ Approx 560KΩ


The first thing they want you to check is the input signal for the ECU.
...If it is OK, check the contact of the ECU connector terminal.
...If not OK, repair ECU connector and terminal.

If you check the input signal for the ECU and it is not OK, then check the knock sensor 2.
...If it is not OK, replace knock sensor 2.

If the knock sensor 2 is OK, repair or replace the harness connector between ECU and knock sensor 2

Maybe someone can scan these two pages and either post them or email them to you.

.

Thx Beav, you are correct:
the 1 old code and 2 new codes I'm getting are:
34: 'EGR solenoid or Circuit'. I have had the this code for over a year, and have never tried to resolve it.
28: 'Knock sensor No.2 (SVX left side)' new code
37: Oxygen sensor (No.2, left side on SVX)' new code

I tried to clear these codes from the ecu and could not, so I suspect I'm either not doing it right, or they are completely dead(shorted/open or missing)

Thx John, I'll be out there shortly to do that basic Knocker resistance test, I'll check both to see if they are the same:p
(SLAP) my girlfriend saw me type that.
" I'm testing my car, Honey, not the neighbours"

Good luck Chris. Hope you can resolve this before the meet this month. :)

Do you realize that the EGR malfunctioning not only raises the NOx emission from your car but also increases its chances for knocking? Not that repairing the EGR will cure your knock sensor code, but it can help your mileage if the knock sensor(s) are working and detect knock that results from an inop EGR. Hope that makes as much sense to you as I intended. ;)

Hi Beav, I do now realize this after your detailed description on the other thread.
The main reason for this repair work is to get my car to pass our smog test: www.aircare.ca standards.
I can either spend $600CDN at an approved aircare repair station, or make it pass, the test is $24.
here's a quick rundown of my last results:
Hydrocarbons(HC) g/km Max allowed: 0.5000, vehicle reading: 0.6922, Avg Passing reading: 0.2338, Result FAILED.
Carbon Monoxide(CO) Max: 9.3200, Vehicle: 7.7610, Avg:1.9412, result: PASS
Oxides of Nitrogen(NOx) Max: 1.2400, Veh: 1.9046, Avg: 0.9452, result: FAILED.

An SVX will still run fine with one cam off a tooth.
And not throw a code.
I have run my Claret with both cams advanced, and retarded a tooth, to see if it made it better or worse (at Bills insistance:rolleyes: )
It ran best with the stock cam timing.

Uhhh.... let me see if I can swipe - oops.. uh, borrow some charts to help diagnose engine management issues from emissions results.

BTW, cam timing may not set codes but that is just because of the various methods the ECU uses to determine malfunctions. However, the tailpipe reveals all, kinda like forensic tailpipe proctology something or other, eh? "Turn your wheels to one side and cough..."

Tom, some cam timing adjustment may be good for specific reasons. Thing to remember is that if there are forty teeth on a cam sprocket (just guessing, I'm not running out to pull a cover and count), one tooth would equal 9° at the cam or 18° at the crank - huge numbers.

Quote of the day:forensic tailpipe proctology
 

I have to just say, what an awesome quote for the day: forensic tailpipe proctology

OK, I checked the right knock sensor and the left, and they are both within spec:
Right = 552k ohms
Left = 570k ohms

So that doesn't mean that I didn't post a code 28 a wj=hile back and now the connection is ok???
Now I'm concerned that I'm reading old codes, and I've not been able to clear them.
Am I chasing ghosts?