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Little problem with my 93 this weekend.

before i get started with what happened, all should know im running revtronix. my car is fully grounded from struts to block to frame all in sequence. that and the chip have been in place for close to a year now problem free. i have other mods listed below.

i started the car up and noticed my check engine light stayed on about 10 seconds longer than usual. didnt have time to check it out so i left it as the light went out right away anyways and never came back.

started it a few times on sunday with no light coming on. just to mention, probably completely unrelated, is my gas light actually came for the first time ever as it has never worked since i have owned it.

anyways, i took the car for a drive today and it felt fine, pulled it into the garage and all of a sudden the light came on for a couple seconds and went out. time to check it out.

blacks together and i got 3 codes. 22, thirty something and fifty something. i should have wrote them down but did not because i thought they would come up with the greens hooked up to. so, greens hooked up and no codes pop up after the start, i didnt even make it out my driveway and i got the steady flash, cpu cleared.

i drove for a little bit with no codes coming in just the steady flash.
i get out and disconnect the green and black, start it up and the engine light comes on. another 22. just a 22 though.

another quick drive without the blacks or greens hooked up and it's sluggish and rpm are tough to get through the 3-4000 range. retarded timing from the knock code of course. im happy its retarding with the chip in it like mike said it would but curious as to where my problem is.
we just went through this over the past few weeks with my dads car and the rubber around the knock sensor was cracked causing his problems. easy fix.

after inspecting my 93's ks and wiring i seen nothing out of the ordinary. although, since i lent both my tool sets to my buddy, i couldnt find a long enough spare extension to actually pull it off, and now that i think about it, the knock sensor could just be cracked at the bottom side. the wire at the connector was slightly visible and had that dirty exposed wire look to it, but it was still connected firmly. so before i get digging into this i would just like some thoughts and opinions.

a question i have is ; will a knock sensor code also show up because the engine has knock, or does the code only show up if there is a problem with the sensor?

help is very appreciated

thanks
Ryan

Could be both, IMO.

Do you have the tools to read what the ECU is seeing? That will be the best way to help understand if the knock sensor is firing a lot, the ecu has retarded the timing a lot, etc.

i could pop by revtronix i guess.

What color is the connector on the knock sensor? They changed colors on the crack resistant sensor. Also - if you need to buy a new sensor, go to Autozone, they have the OEM sensor for $50. The dealership wants $88 for the same part. Same manufacturer and part #.

it look like a couple of ppl have been having the same problem.

It is possible for the sensor to be bad without it being externally obvious. The original sensor had a problem with internal cracks, and that's why they redesigned it like n2x4 says.

If the sensor has a gray connector on it, it's the original design. If it has a white connector, it's the new design.

But even if it's the new design it still looks like you should replace yours. If the wire is exposed, that's bad. It's subject to a great deal of corrosion and it's unshielded.

With a stock ECU the knock sensor trouble code is only thrown if there's an electrical problem with the knock sensor. Excessive engine knock doesn't result in a trouble code. I have no idea if Revtronix changed any of that, though, so you might ask them about it.

vrg3 wrote:I
With a stock ECU the knock sensor trouble code is only thrown if there's an electrical problem with the knock sensor.

The ECU throws a code if there's a problem, but your scantool actively registers knock if the sensor finds any, right?

Yes, that's correct.

i see, if i remember correctly, the terminal is white. about 1.5mm show of wire on the knock sensor side of of the connector.

im going to check for continuity when i get home. the car now has about 145,000 km on it. Up here in Canada, the dealer wants 165 and the parts store wants 170 with a discount for a KS

i'm thinking i'll be popping across the border in the next couple of days.

thanks for your reply's guys.

im hoping the other two codes that i didnt record are related.

update's asap

Now when the sensor goes bad what happens? does the ECU disregard all signal from it? does the sensor lie to the ecu making it think that it is perpetually knocking? does it do the opposite and not tell it anything? and why does the housing having a crack make it stop working?


Also i got a code 22 a couple weeks ago and nothing since.Does this mean that the problem was temporary or is it most likely that the thing is junk? - thats about all i need to know about knock sensors lol.

If the code is active, the ECU ignores the signal and sticks to base timing.

It sounds like Revtronix's modifications make it go into kind of a limp mode.

If the code's not active, then the ECU does tend to think there's knocking when there isn't anything actually happening.

A crack in the housing is indicative of a crack in the transducer itself. It also can cause the sensor to rattle since it's no longer mounted as securely.

If you got the code intermittently, you may have a sensor that's on its way out. If you notice any driveability problems or hesitation it may be because of that sensor.

Well once again Vrg3 and I disagree....

I have heard of people getting knock sensors codes from worn motors and/or faulty fuel, so I reckon that anything that can make the signal go out of range, or in other words, the ecu unable to correct the knocking by adjusting the timing enough to stop the knock, can set the code.

I don't know how the revtronics is set-up tjough so I'd advise you to ask them what the criteria are for that code to be set.

Apart from the wrong fuel, knock can be caused by rattling pistons, oil burning, overheating, carbon build-up/localised hotspots, over boost... anything that can cause knock.

Revtronix claims that there chip retains all of the ecu features and the car will go into limp when told so.

I popped the sensor out tonite, i noticed the connector was white. i studied it very closely to find two small hairline cracks about that ran through roughly 40% of the black plastic on top.

Now compared to my dads that we just fixed the crack was easily noticeable right through the plastic on top.

What i am thinking at the moment is my sensor is just starting to go and since the code is stored in the ecu now my timing is limp hence the lack of power and very noticable hesitation.

i am wondering if the ks is stock, it reads ; 6110 UNISIA JECS JAPAN 22060 AA031 ???

That is the part number for the new-design knock sensor.

If there are hairline cracks in the plastic on the outside, your sensor's toast. No damage is acceptable. You can't know what condition the inside of the sensor is in.

Sounds like you know what to do now!

log1call wrote:Well once again Vrg3 and I disagree....

I have heard of people getting knock sensors codes from worn motors and/or faulty fuel, so I reckon that anything that can make the signal go out of range, or in other words, the ecu unable to correct the knocking by adjusting the timing enough to stop the knock, can set the code.

I don't know how the revtronics is set-up tjough so I'd advise you to ask them what the criteria are for that code to be set.

Apart from the wrong fuel, knock can be caused by rattling pistons, oil burning, overheating, carbon build-up/localised hotspots, over boost... anything that can cause knock.

For the first generation Legacies, what you describe above as happening is very unlikely. The OBD1 diagnostics in these cars is not that smart. In an OBD2 setup, it could be very possible.

Here is a list of the ECU codes & fail-safe operation.

http://www.main.experiencetherave.com/s ... ration.pdf

The knock sensor code will be displayed when: "Abnormal voltage produced in knock sensor monitor circuit"

Based on my experience and from reading over the factory manuals, "abnormal voltage" typically means anything outside of the sensor's normal range of operation. So, just detecting large or frequent knock indications should not throw a trouble code.

thanks, nice info josh.

so since the new border laws prevent me from crossing the border, would anybody be willing to send me an oem replacement from down there as they are over $100 cheaper.?

maybe something through paypal or i could prepay it on a credit card and and maybe someone could pick it up for me???

Im in vancouver bc if anyone is interested, throw me a pm please.

In case you can't find a board member to help you out, these two eBay auction listings say they'll ship to Canada:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0355839624
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0348031225

Sheesh! If I wouldn't have needed that sensor so badly I'd have ordered it from ebay!

Let me know if you need help getting one, I don't mind assisting...

you guys are too kind.

i think i may just have the one in the first ebay link for 30. but is it oem. he says the brand is subaru. i only want oem or jecs

I'd buy it - it looks right to me.

well, i picked up a new ks from the wrecker free of charge. it seemed to be in good condition, oem part with white connector. i love the regained power.

and it may just be me, but the car seems more powerful than it was in the winter. it was getting a little doggy when the weather warmed up. i figured it was the heat but after driving it last night im thinking my timing has been slightly retarded as the ks started to go.

thanks for the help.

RJ93SS wrote: im thinking my timing has been slightly retarded

I hate retarded cars

Glad it worked out. I make it a habit to replace any knock sensors I see that are using the old connector. Can make a huge difference.