Cracked knock sensor

[uberaudi]

I picked up a '91 20vt Avant and have been slowly getting it ready for daily driver status. It seems like it's a bit low on power, but don't know for sure, as this is my first one. My 20vt chipped battle wagon seems like it could entertain the 20vt, and I just can't let that happen.

It has an Intended Acceleration chip and hits a consistant 22psi on my Podi gauge. I fixed a major boost leak with the 034 breather and throttle body silicone and it seemed better but not quite there. It also has an Apikol all aluminum intercooler with Samco hoses. I changed all the vac lines with silicone as well as tested the BPV to make sure it holds vacuum. New VC and TB gasket too. I feel like the intake/vac track are good to go.

I don't have (or it's burned out) a check engine light in my cluster so I scanned the codes with the LED test light and got the 2113 code (hall sensor/cps). It starts right up everytime so I pulled the #27 fuse so erase the codes and it hasn't come back.

The car runs great, but just seems slow. But tonight while poking around I found this:


Both of my knock sensors are cracked and the sheathing on them are deteriorated as well. I'm not throwing any codes, but they look pretty bad so I'd like to replace them. I see that AutohausAZ has the blue one for 30 bucks, but where can I source the other? Are they the same one? Could this be the/one of the sources of my low power even though I'm not throwing the code for it?

I'm trying to get this pig ready for the last track day of the season (Sept 20th) so I need all the power I can get! A couple pics of the car right after suspension got installed. Still need to dial in the height.

[elaw]

GAP has green ones: http://www.germanautoparts.com/Audi/S6/EngineElectrical/314/1 PartsGeek.com does too.

As far as I know, the green one would work in both positions - the only difference is cable length, with the green being longer. You'd just have to ensure that you don't swap the wires - each sensor must be hooked to its proper connector.

[uberaudi]

Ouch, 160 for the brown knock sensor?! Does anyone know of alternatives that would work? Could knock sensors in poor condition retard timing, even though it doesn't throw a code?

[elaw]

Brown... huh? I thought 3B used blue and green just like AAN.

Go to the link I posted above... genuine Bosch for under $30. Grab two, pop 'em in there, you're done.

[uberaudi]

I hope that's the case, but GAP says otherwise for the 3b:

http://www.germanautoparts.com/Audi/200 ... ical/314/3

If I could get affirmation that the AAN ones work then I'm game for sure!

There's a 7.5" difference between the lengths..

[88a5tq]

Could knock sensors in poor condition retard timing, even though it doesn't throw a code?

This was the problem I originally saw with my old crumbly sensors when I first got the car. Imagine constant limp mode with the severe condition mine were in.

Do yourself a favor and use a proper torque wrench when installing them. Over-tightened ones, I read, will cause the same ignition retardation as well.

Wow I used the light green $9 ones on ebay for my 200

They've never "heard" a knock!
Also plugs confirm the sensors are probably right

Also, does your boost readout in the autocheck display in the instrument cluster show a boost reading. The other issue I had was my hard ecu vac line was split where it entered the firewall by the steering rack.

[uberaudi]

Interesting...I see there's an assortment on egay. Did you have any issues with the length of the two?

Unfortunately, my autocheck is entirely scrambled, but I do have an analog boost gauge installed verifying 22psi.

[uberaudi]

Is this the one you used?

http://www.ebay.com/itm/KNOCK-SENSOR-AU ... 50&vxp=mtr

[uberaudi]

Might just go with this one actually...a 20 dollar Bosch. Looks like the same plug.
http://www.ebay.com/itm/271618896101?_t ... EBIDX%3AIT

[88a5tq]

Neither was too short. It's simple enough to tuck them away behind the p/s rez cap for the one closest to the firewall. I have to say I don't recognize the box in the pics for that sensor. I'll have a quick look today as I see another at the bottom of that page for A4's but it shows a p/n on the actual sensor. I'll get back to you.

[uberaudi]

Awesome, thanks 88a5tq and elaw!

[elaw]

I hope that's the case, but GAP says otherwise for the 3b:

http://www.germanautoparts.com/Audi/200 ... ical/314/3

If I could get affirmation that the AAN ones work then I'm game for sure!

There's a 7.5" difference between the lengths..

Doh! I wasn't thinking, I was looking at the sensors for an S4, thinking it had the 3B which of course it doesn't.

Sounds like you might have to measure the wire... a few inches too short would definitely be a showstopper.

[themagellan]

Hi - Welcome, and nice avant.

I went through this same issue it ended up being a G28 sensor. I used these sensors(I think a few other users have too) and it worked great in my car.

Like others have stated, you can use the same sensor, just make sure you do them one at a time or mark(Add a ziptie) to one so you know where they're going.

Also check the vacuum line from your ECU to your engine compartment if you haven't it's a really easy fix.

If you like reading and haven't seen this, I would suggest it!

http://www.sjmautotechnik.com/trouble_s ... ouble.html

Enjoy and hope it fixes some issues.

http://www.ebay.com/itm/NEW-CRANK-POSIT ... b9&vxp=mtr

[88a5tq]

Holy crap that is a fantastic price! Of course I have a full set from an old car. But you can bet I'd buy that ebay one before the genuine one.

[Aktapod]

Just be careful installing the eBay G28 and G4 sensors! I bought a set from a link on themagellan's thread (Thank you, btw!), but the ones I got ended up being a millimeter too long and scraped the flywheel when I turned the engine over by hand. If I'd just tried to start it, I probably would've sheared off the ignition reference pin, but I shimmed it 1mm and it's been working since!

And +1 for the blue and green knock sensors! Got mine from autohausAZ ad they solved a constant limp mode at high RPM.

[uberaudi]

Great, thanks for the additional info Kevin and themagellan. Fixing a sheared timing pin doesn't sound like a fun job to tackle!

I'll see if that code is thrown again in a bit and if it is will go ahead and order up the G28 as well, thanks for the link.