Knock sensor question

Joined
6 September 2004
Messages
1,349
Location
Arundel, QLD, Australia
I am curious, do the knock sensors go bad over time?

I have just fitted an AEM & have noticed on the dataLogs during tuning that the 2nd bank(I assume rear bank) has double the voltage readings of that of the front bank. (I'm sure there's no detanation as this is at light load & cruise.)

Could this be caused by overly large valve clearances. (Haven't had a chance to check as yet) The valvetrain seems a little noisy but assumed this was normal

or could this be a LMA problem

Thanks
 
No, HP/Custom Turbo setup. 6psi

I have the same issue with my bank two knock sensor, I even replaced the knock sensor to try and find out what was going on. I never found out why the sensor was reading more noise than the bank one sensor. I had an idea that maybe it was mechanical noise from the CTSC blower it self since it is mounted directly above the knock sensors, but I guess that is not the case since you are seeing it and you have a turbo.

I am wondering if it is a ground issue. Do you have a lot of erratic readings from the coolant temp sensor as well? Mine will bounce around from 190 to 220 degrees when the engine has warmed up.

Dave
 
I have the same issue with my bank two knock sensor, I even replaced the knock sensor to try and find out what was going on. I never found out why the sensor was reading more noise than the bank one sensor. I had an idea that maybe it was mechanical noise from the CTSC blower it self since it is mounted directly above the knock sensors, but I guess that is not the case since you are seeing it and you have a turbo.

I am wondering if it is a ground issue. Do you have a lot of erratic readings from the coolant temp sensor as well? Mine will bounce around from 190 to 220 degrees when the engine has warmed up.

Dave

I haven't noticed any erratic readings but it does seem to run hot going by the AEM. Temp gauge in the dash reads normal but AEM says I'm at 100 D(c) when at operating temp. not sure what that is in (F)
 
I haven't noticed any erratic readings but it does seem to run hot going by the AEM. Temp gauge in the dash reads normal but AEM says I'm at 100 D(c) when at operating temp. not sure what that is in (F)

The sensor calibration for IAT and Coolant is definitely off. There are revised calibration tables available on AEM's forums (www.aempower.com)

Regarding the knock sensors - we have seen similar effects. The readings are very sensitive to proper grounding through out the engine. If you use a wideband controller, make sure this is properly grounded as these have a big impact on the readings from the knock and other sensors.

Cheers,
-- Chris
 
With my HP setup, we replaced the stock IAT sensor with one located in the aftercooler, as the OEM manifold location was prone to heat soak (we would notice the temps dropping while under WOT).

I recall the tuner mentioning he had to turn down the sensitivity of the knock sensor, due to vibration 'noise', he was able to manipulate the graph to show this was noise, rather than knock.
 
The sensor calibration for IAT and Coolant is definitely off. There are revised calibration tables available on AEM's forums (www.aempower.com)

Regarding the knock sensors - we have seen similar effects. The readings are very sensitive to proper grounding through out the engine. If you use a wideband controller, make sure this is properly grounded as these have a big impact on the readings from the knock and other sensors.

Cheers,
-- Chris

Thanks Chris, I'll check all the grounds, maybe I'll make a new engine ground cable directly to the Battery.

Does anyone have a copy of these revised AEM Calibrations or a link? I've been searching all over the AEM Forum & have not found them.

Thanks In Anticipation.
 
With my HP setup, we replaced the stock IAT sensor with one located in the aftercooler, as the OEM manifold location was prone to heat soak (we would notice the temps dropping while under WOT).

I recall the tuner mentioning he had to turn down the sensitivity of the knock sensor, due to vibration 'noise', he was able to manipulate the graph to show this was noise, rather than knock.

Yes, looks like I've got the same problem, engine actually gets less knock sensor volts with more revs/boost
 
I know this post is old and I don't know if it had being posted, I searched I found nothing I got this from the AEM forum.
For the coolant sensor.

Voltage....Temperature (F)
0.............261
0.16.........246
0.31.........214
0.47.........185
0.62.........165
0.78.........153
0.94.........140
1.09.........131
1.25.........122
1.4...........115
1.56.........108
1.72.........100
1.87.........93
2.03.........88
2.18.........82
2.34.........77
2.5...........72
2.65.........66
2.81.........61
2.96.........57
3.12.........52
3.28.........46
3.43.........41
3.59.........36
3.74.........30
3.9...........27
4.06.........23
4.21.........19
4.37.........16
4.52.........12
4.68..........9
4.84..........5
4.99..........3



<O:p>
For the IAT

261 261 241 230 219 210 199 189 180 169 158 149 142 135 127 122 115 109 104 97 90 82 77 70 64 57 50 43 36 28 21 16 10<O:p></O:p>

</O:p>
 
Whow, is the removal and replacement easy? I had assumed it requires some type of engine dissasembly. What are the steps?

Not entirely sure what you mean. The engine is still OEM & untouched I made a jumper harness to connect the Motec to the OEM ecu harness. I still use the OEM sensors except the Map sensor, although I could have.

I'm tuning on the dyno as we speak.
 
FYI...Apparently, the louder noise from the engine/turbo/supercharger/etc reaks havoc on your knock sensors, properly grounded or not! Talk to Mike at Autowave, as they know how to correct the issue! I did!
 
Yes Mike told me the same thing he disabled my knock control on the AEMPro.
 
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