97 1.9 Z3 Knock Sensor Code

[Cardriver333]

I'm getting the CEL, I read it in INPA and i translated it below (knock sensor 2). Just to make sure, that means the cylinder second from the very front of the engine is knocking right? I've already tried switching spark plug 1 with spark plug 2, swapped in a different spark plug wire i had laying around, swapped an ignition coil with an extra i had in the garage.

I drove in between doing all of these things and still got the same code just with sligh variation in the numbers, but always on knock sensor 2. Because it's always on knock sensor 2 wouldn't that mean it is an electrical issue?

When I first got it running a year ago I filled up with 87 before I knew better and added octane boost when I learned it needed more octane, then the only gas I've put in since then was 4.5 gallons of shell 91.



211 knock sensor 2 sensor signal

Error frequency: 1
Logistic counter: 40

Engine speed 2520 1/min
Load signal 2.55 ms
Engine temp 67.50 grad c
Occured before (rel. BZ) 0.20 h

Below the minimum value

emission relevant error (after debouncing mil on)

Error present at the moment

Static error

 

[Zephyr]

Hi
maybe it is just what is says, the knock sensor is bad. M43/M44 have a knock sensor (a sensor with two cables attached to the engine block) that can go bad with time.
what engine is yours? An M44 i presume. The part number is 12141247993 and is quite expensive.
Before ordering one, check with inpa your “smooth running values” menu, it will give you a reading of your four cylinders with numbers from zero up to sometimes hundreds.
on a warm engine, at idle, these values have to be as close to zero as possible and do not have differences from one another more than 1.5.
if the second cylinder (or some other cylinder) is constantly above we then can check some other things. If these values are “all over the place” then say hello to my little friends called cam sensor and idle valve.
cheers

 

[Cardriver333]

Yeah, M44. I found the sensor for $35 online so I'll replace that just to be sure. The smoothness says
1-----32
3-----129
4-----196
2-----77

 

[Zephyr]

Yeah, M44. I found the sensor for $35 online so I'll replace that just to be sure. The smoothness says
1-----32
3-----129
4-----196
2-----77

Hm… so these values are taken from a warm engine (needle to the center) and on idle at about 780/850 revs, correct?
if this is the case, and you would like to further dig further into your engine, please put your MAF readings.
I suspect you are having either a vacuum leak, or some erratic oxygen sensor issue.
I had the exact problem and almost replaced half the sensors (pcv, idv, coil, wires, cleaned injectors, etc) but finally after the advice of a certified tech, I smoke tested the engine, replaced the injector hoses that were leaking, the broken return hose from the valve cover to the air filter and finally the idle control valve and cleaned the maf.
Now my values are maxing at 0.50 (like your first cylinder) and I feel very happy about it.
it wasnt needed - the engine worked almost fine- but I did it just because…. ;-)

 

[Cardriver333]

Here are pictures of the other screen running vs not running. If the pictures are unreadable let me know and I'll type all of it out.

 

[Zephyr]

Having a value at the idle air consumption with engine off is a bit strange and that is why there is an exclamation mark there, but it seems ok with the engine running so no issue there.
your needed air is quite high, so lets wait for your sensor to arrive and read again.
i would remove and clean the idle air valve (please DO not pry it open as shown in some videos, it WILL break please please do not do it) just clean it with carb cleaner (spray and shake - repeat) and put it back using a new flange/gasket. And lets check again after the sensor arrives. Your engine is doing fine (from what these numbers say).

 

[Cardriver333]

I got everything put back together with new knock sensor and new idle control valve and im not seeing the CEL anymore so far...