Re-wire knock sensor?

LegacyPunk · Post by **LegacyPunk** » Thu Sep 30, 2004 7:39 am

Well, A while ago after my first knock sensor crapped out, Ive noticed that my car has lost the punch that it once had, even my dad thinks so. I replaced the knock sensor, brand new from the devil, still no luck, still code 22. Anyway I figure out that its the wire that leads to the knock sensor, it was smashed between the tranny and the block and a part of the inner wire was exposed. SO....I tried to rewire it but with no luck. Anyone know how I could re-wire this thing?? its like a wire within a wire thing. I connected the inner wire to the white connector, still nothing (it was like this before and it seemed to work, the outer "metal shielding wirey stuff" wasn't connected).
Maybe I just need new plugs and plug wires who knows. Any ideas and help would be GREATLY appreciated, I just want my car to go back to its spirited old self.

vrg3 · Post by **vrg3** » Thu Sep 30, 2004 3:28 pm

It's just a shielded wire. Both the shield (the outer braid) and the signal wire (the wire in the middle) connect to the ECU. The ECU internally grounds its end of the shield.

If your wire was crushed in between the transmission and engine, maybe the signal wire is shorting to the shield somewhere (and therefore to ground) somewhere. Or even if it's not shorting to the shield it could be shorting directly to ground if it's exposed.

If you want to properly rewire the sensor, you need to get a shielded cable and run it from the ECU to the sensor, splicing it in at the ends. If you properly sheath it, shielded microphone cable should do.

LegacyPunk · Post by **LegacyPunk** » Thu Sep 30, 2004 8:08 pm

well, that sounds more complicated than I hoped. So the outer braiding isn't supposed to touch the inner wire? What If I just completley bypassed the white connectors? Just connect the shielding to the shielding and signal wire to signal wire. kind of like 2 wires where each wire connects, or does the shielding have to be like it is?

Thanks for the help, ive been tryign to track this sucker down for quite a while.

WRXdan · Post by **WRXdan** » Thu Sep 30, 2004 8:44 pm

If you let the wire shield touch the signal wire then it will ground the sensor. This will throw a 22 everytime. If you crushed the wire then it's possible that the sheild is touching the signal wire core. Cut back beyond the crush point and rewire it. My shield doesn't connect to anything on the sensor side.

vrg3 · Post by **vrg3** » Thu Sep 30, 2004 8:44 pm

What part of it sounds really complicated?

Right, the outer braiding is supposed to just surround the inner signal wire, to keep electromagnetic interference out. They're not supposed to make electrical contact.

I don't recommend you bypass the stock connector... if you do, it will be a humongous pain to replace the knock sensor.

The car's shielding only goes up to the connector. (It's a gray connector, I think -- not white. The white connector is on the sensor side if it's a redesigned sensor.) The shield before the connector is not connected to the shield after the connector, I don't think.

So disconnect the knock sensor and clip the car's harness connector an inch or two back. Splice it onto your new shielded wire, route that new wire through the firewall, and splice that wire to the ECU's connectors (after cutting them).

Right?

LegacyPunk · Post by **LegacyPunk** » Thu Sep 30, 2004 9:39 pm

Right. Now I just need to go buy a sheilded wire and hope that this is the true source of my code 22.

Sir Yach-o · Post by **Sir Yach-o** » Wed Oct 06, 2004 7:51 am

I've had the same problem for months and can't diagnose it. I'm down to thinking that my ECU went bad somehow. I haven't rewired, but I've checked anything I could continuity-wise, and resistance, and from what I can tell everything checks out. My car is stuck in timing retard mode.

Beyond frustrating.

vrg3 · Post by **vrg3** » Wed Oct 06, 2004 2:54 pm

Have you checked the wires with the engine running and warm? While shaking them vigorously? Heat and vibration can bring out the problems.

Have you've also tried replacing the sensor itself?

Sir Yach-o · Post by **Sir Yach-o** » Wed Oct 06, 2004 8:32 pm

Personally, I've tried freakin' everything aside from rewiring. I've got the day off today, so I might as well get off the computer here and try it. BTW, I've tried a total of four sensors, 2 junkyard and 2 baby's-ass new from the dealer. My issue has gotta be past the sensor at some point. I'll update.

Sir Yach-o · Post by **Sir Yach-o** » Wed Oct 06, 2004 9:50 pm

Nope, not the wiring.

vrg3 · Post by **vrg3** » Wed Oct 06, 2004 10:13 pm

How did you rewire it?

Sir Yach-o · Post by **Sir Yach-o** » Wed Oct 06, 2004 11:16 pm

I cut the sensor's connector off, then spliced the signal wire to a shielded mic cable. Then went right to the ECU through the firewall and twisted the corresponding wires to the ecu harness wires. . Tested everything to make sure the signal wasn't grounded, and went for a ride. No luck.

vrg3 · Post by **vrg3** » Wed Oct 06, 2004 11:32 pm

D'oh.

Did you try one of the other three sensors?

Sir Yach-o · Post by **Sir Yach-o** » Wed Oct 06, 2004 11:36 pm

Not with the new rewire. It's s PIA because of my intercooler. I've got faith in the sensor I've wired. The resistance checks out, and it's the second new one. Besides, unless the circuit is open or shorted, the CEL wouldn't throw, right? Like, if you've got just a bad sensor, you just notice a bit of the hesitating timing retard, it doesn't throw a CEL. Is there any harm in throwing in an ej22 NA ECU to check things? I've got one of those laying around.

vrg3 · Post by **vrg3** » Wed Oct 06, 2004 11:42 pm

You're right that an open or short circuit does cause the CEL, but that's not necessarily the only thing. I don't know about our ECUs in particular, but some Subaru ECUs test the knock sensor periodically by forcing the engine to knock and making sure the sensor picks it up... I remember a story once about someone who got a knock sensor trouble code when using race gas because of that. I have no idea what kind of Subaru it was though.

An NA ECU won't be able to start your engine unless you switch the cam and crank sensor signal wires. If you do, it'll be able to start your engine but I'd drive it as little and as gently as possible. But, yeah, if the NA ECU doesn't throw a knock sensor CEL then that's a useful piece of information and might point to a bad ECU.

Sir Yach-o · Post by **Sir Yach-o** » Thu Oct 07, 2004 1:03 am

Well, I'm not on race gas, that's for sure. I might try the NA ecu and switch the cam and crank sensors. Sounds like a lot of work though, but I might be out of options.

Sir Yach-o · Post by **Sir Yach-o** » Thu Oct 07, 2004 2:18 am

Well, I switched the cam and crank sensors, and ran the engine off of the NA ecu. The car ran like hell, and threw 2 CEL's. One was the canister purge soleniod(no suprise there) and the other was code 24, air bypass soleniod? (I'm taking them from the FSM)

But, there was no code 22.

I'm thinking bad ECU. Can't figure why, though. I'm gonna grab a friend's and drop it in. Then we'll see for sure. And then I'll be FORCED to buy a Link plus when I do my rebuild.

vrg3 · Post by **vrg3** » Thu Oct 07, 2004 11:52 am

What's the NA ECU's part number? If it starts with 22611AA56, then it's meant for a completely different kind of IAC valve and so the code is unsurprising.

Sir Yach-o · Post by **Sir Yach-o** » Fri Oct 08, 2004 1:39 am

Yeah, that's the ECU i've got. What did suprise me is that i got no code 22. The others, sure, I'm not that suprised either, but no 22. Does that mean my ECU's f'ed? I'm guessing so. I'm still gonna try my buddy's turbo ecu in there when I get the chance.

vrg3 · Post by **vrg3** » Fri Oct 08, 2004 4:20 am

Yes, it's possible that your ECU's malfunctioning. Swapping in a different turbo ECU would be a good way to make certain.

The ECU might be repairable. You might pop it open and see a burnt out trace or a spilt capacitor or something.

Sir Yach-o · Post by **Sir Yach-o** » Fri Oct 08, 2004 5:20 am

Here's hoping.

93Leg-c · Post by **93Leg-c** » Tue Jul 10, 2007 7:43 am

Resurrecting an old thread, but . . .

LegacyPunk and Sir Yach-o, did your code 22 issue ever get resolved? If so, how was it solved?

def09 · Post by **def09** » Sat Aug 04, 2007 9:53 pm

I second that! Please reply fixed or not.

asc_up · Post by **asc_up** » Fri Oct 26, 2007 7:30 pm

reply....... lol

TheDaveler · Post by **TheDaveler** » Tue Dec 04, 2007 12:06 am

How many people have actually had to re-wire from the ECU?

I have a similar problem, Code 22. I have not replaced the sensor, but after reading this thread I may not need to.

My symptoms are, every once in awhile the check engine light will turn off, but for the other 95% of the time, The light is on and my timing is retarded (Literally)

Any thoughts? (I hope its just the wire)

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Re-wire knock sensor?

Re-wire knock sensor?