1.8T Knock Sensor ECU – Install & Setup
5 min read
In this video we install the KSC3 standalone knock sensor ECU onto a VAG 1.8T engine
The Engine
The engine is running a K04-064 turbo running around 300bhp.
We do not have the ability to alter ignition timing during the setup process so the use of audio from the knock sensor will be essential
Why are we installing a KSC3 on this engine?
The engine is running the stock ECU which uses it’s own knock sensor.
The purpose of installing the KSC3 is to get an idea of if/when the engine is knocking and how effective the stock knock detection strategy is, how often knock is happening (if at all) and if it is occurring, how bad it is before the engine ECU steps in.
Wiring
We are powering the KSC3 from the MAF sensor power and ground. RPM signal is being taken from number 1 coil pack signal. We are not using the load input (the load input will be connected to a permanent 5v signal).
We are using the LEDs to indicate knock and we are using an extra knock sensor connected directly to a laptop to listen to engine knock and to help us set a volume threshold for the KSC3.
Audio
The first step after wiring in the KSC3 will be to get an idea of how well our knock sensor placement is performing. We are using two knock sensors sandwiched on top of each other and the best place I could find was on the intake manifold.
Assuming the signal is good, next step is to get an idea of how the engine is performing with regards to knock (Is it? If so, how often? How bad?).
Result
We found the knock sensor placement was good.
And as a side-note, that the engine can knock slightly at low RPM and higher load and that we may have a loose chain tensioner.
Generally speaking the audio signal to the headphone and KSC3 is good.
KSC3 Setup – Programming the settings to detect knock
Before we start entering our settings into the KSC3, the first step is to use its Test function to check our wiring is good.
Everything checked out and we move on.
Knock Frequency
Because we don’t have a way to adjust ignition timing on this car, I am going to use the knock frequency calculator to get the theoretical (actual knock frequency detected by KSC3 may be different) knock frequency of the engine. Instead of using the KSC3s Knock ID tool.
The bore of the 1.8T is 81mm, this gives us a theoretical knock frequency of 7072Hz. I’ll set the frequency detection window to Low Frequency 6.4KHz and High Frequency to 8KHz.
Engine Load
Load Threshold (we are not using this)
RPM
RPM signal will be set to 0.5
Baseline Engine Volume
With that done, we can do a Baseline Calibration to find out the normal volume, in our frequency window, at three RPM points.
**It’s key that the engine is not knocking at all during this process.**
We start rolling in second gear around 1500 RPM and gradually get into the throttle and press “Off” at the redline of the engine before we lift off.
On this first pull the chain tensioner noise seemed excessive, the mid RPM volume seemed high.
Second run seemed a bit more normal and the numbers were more in line with what we would expect but there is still what seems to be excessive mechanical noise.
At this point we’ll set the volume limits so they pick up this mechanical noise. The mechanical noise needs to be investigated to see if there is some sort of problem with the engine. As it stands the KSC3 is indicating this engine noise which is a good thing. The engine will be looked at to see if, what seems to be excess mechanical noise, is normal or not. When the condition of the engine is confirmed we can finalise the settings of the KSC3.
Under normal circumstances, assuming we hadn’t heard anything unusual this would be the base settings done. We could then move on to verifying the settings by driving the car and seeing if the KSC3 is picking up knock.
Audio Validation/Verification of Settings
This was covered in a previous video here. To describe the process briefly, we drive the car while listening to the knock sensor audibly (with headphones) and watch the LEDs. We want the LEDs to illuminate when we hear knock in the headphones.
Fine Tuning – KSC3 Settings
If we are not happy with the performance with the Baseline numbers we entered above, the first step would be to drop the volume slightly and see if that gets us where we need to be. If not, I’d return to the previous volume threshold numbers and increase the High Frequency window number by a 1KHz or so. And validate again. We repeat the process until we get the performance we need. But generally speaking, we should be in the ballpark with our initial numbers.
In this case, our lower RPM volumes seemed a bit low, the KSC3 was indicating knock when perhaps there wasn’t any. Raising the volume threshold by one point gave a good result but at higher RPM the (excessive?) mechanical noise was in the same frequency window as genuine knock. Again, the condition of the engine, in this case, needs to be verified before the fine tuning process can be completed.
Setup Process – Key Points
Audio
Verifying our settings during the setup phase with an actual audio feed from a knock sensor is essential.
We need to know if and when the engine is knocking to be sure the numbers in the Baseline Calibration are good.
And if we can adjust the ignition timing of the engine and we are using the Knock ID Tool, listening to the engine during the knock ID process confirms if the engine knocked during a run.
Stock Knock Sensor
There is slight an occasional knock at low RPM and higher load which the stock knock sensor seems to deal with well. Although there does seem to be points where light knock is present for longer periods than ideal.
Engine/Mechanical Condition
During the setup process it’s possible that we could find potential issues with the engine that we weren’t aware of. In this case, the sound we found was not evident at all from the cabin or listening to the engine normally ie it was only evident when we listened to the knock sensor signal. Any potential issues need to be rectified before setting up the KSC3.
Reading The LEDs
The LEDs illuminate when the KSC3 detects what it thinks is knock. Observing the LED colour when the car is driven can tell us some things.
Using the KSC3s ECU output
If we are sending the knock signal from the KSC3 to our engine ECU, the LED colours tell us a story which can help us make decisions on what to do with our ignition timing. There is an in-depth article on that here.
If we are just using the LED indication, we don’t get as much information and their story is a bit different, read more here.
