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It will retard as needed. It won't advance once it reaches it's limits so you have to reset if you expect LESS knocks.
I have an update for you soon which fixes a bug, adds some feedback, and provides an easier way to reset the learning. You'll just have to hold the accelerator to the floor while turning the key to ON then release the pedal before starting. If you have a CEL wired it will come on and stay on until you rev over ~1800 rpm to indicate the memory has been cleared - either with the pedal or the battery disconnected.
Speaking of the knock light I was wrong about the voltage output. When programmed for a steady state ON it puts out 11 volts with the engine off. While running, the output is only ~1.6 volts as it is pulsed on/off rapidly.
For a knock LED it may be simpler to use the CEL output which goes to ground when active and use the switched 12V in the diagnostic plug. (The 87-88 square plug has a CEL terminal.)
Since the knock output is difficult to work with and two outputs aren't needed I am going to return the knock output to stock (no delay added) and only use the CEL output on future versions. Then the knock output can concievably be used again with knock counting boxes (Theo/Hammer).
It will retard as needed. It won't advance once it reaches it's limits so you have to reset if you expect LESS knocks.
I have an update for you soon which fixes a bug, adds some feedback, and provides an easier way to reset the learning. You'll just have to hold the accelerator to the floor while turning the key to ON then release the pedal before starting. If you have a CEL wired it will come on and stay on until you rev over ~1800 rpm to indicate the memory has been cleared - either with the pedal or the battery disconnected.
Feedback with light confirmation is all. Without the light you will just have to trust that holding the pedal to the floor and turning the key to ON will reset it (the updated version).
If you did want a light (with the update), the CEL output is a plain old switched ground for a dash lamp so you could hook even a incandescent bulb up to it.
On the 87-88 plug - see above
Pin #1 - switched 12V
Pin #11 - CEL ground
@PorKen dropped off the latest version of the EZK self tuning chip and walked me through some of the new features. Ken said he fixed a couple of software errors that were preventing the chip from fully advancing or retarding the spark to the maximum levels while still minimizing knock events. He also updated the diagnostic knock indicator light behavior, and added a few more features. Here are some if the new features.
He changed the knock output pins to work with the "check engine light" (CEL) outputs, so that later 89+ models get the knock indication on the existing CEL indicator on the dash. For 87/88 cars, we need to wire in our own light (see post 133 for how to do that). Here is an overview of the indicator lights work:
After memory reset, it will stay illuminated after starting until 1800 RPM is reached
After startup, it will stay illuminated for 2 seconds
Knock detection, it will illuminate briefly for each knock detection.
Knock detection error, it will stay illuminated constantly
Here are some of the other changes that were made
Faster Adaptation
Adaptation applied only after engine is sufficiently warmed, the block has expanded and cam timing is equalized between left and right sides.
ability to reset the adaptation by turning the ignition to the "on" position while pressing the accelerator to WOT (do not start the car). This will clear all stored adaptations without the need to disconnect the battery. This may be useful when changing octane at the pump.
Longer illumination of knock indictor when knocks are detected. Before the knocks would flash very quickly. Also the new pin out uses a 12v voltage so you can use just about any LED bulb. Whereas before you needed to source a 5v LED which are not very bright.
More spark advance and retard capabilities @PorKen please provide additional comments on what you did. I cant remember.
Test Drives
I was able to put the new program through the paces on a long drive and on my regular oval. I must say the improvements are significant over the last version. The car has so much more urgency and brute force acceleration and it sounds so much more angry
@PorKen has modified the EZK chip to provide some helpful signals via the Check Engine Light (CEL) for '89+ models or via the diagnostic ports for 87/88 models that do not have the check engine light. For the 87/88 models, we need to build a diagnostic cable with a light to get the same indications. I'll cover that below but here is an overview of the output signals to the CEL (diagnostic light).
After memory reset, it will stay illuminated after starting until 1800 RPM is reached
After startup, it will stay illuminated for 2 seconds
Knock detection, it will illuminate briefly for each knock detection.
Knock detection error, it will stay illuminated constantly
For early cars (87/88) you can build a test light by using PIN 1 and 11 on the diagnostic port. You can do this by soldering leads to the blank socket cap that is plugged into the port.
Diagnostics port PINOUT on a 928s4 MY 1987/ 88 1 over fuse 7 to bus 15: switched 12v
2 gnd via MP IX + shield ground
3 pin 13 EZK: Speedpulse to LH pin 1
4 pin 14 EZK: knock registration input from diagnose plug to EZK
5 over fuse 24 to bus 30: unswitched 12v
6 nc
7 nc
8 nc
9 pin 22 EZK, shielded: Hall sender pulse
10 pin 12 LH+EZK, shielded: K-line diagnostics 11 pin 22 LH: Display (check) Engine check
12 pin 7 EZK, shielded: L-line diagnostics
Here I build a test light that can be plugged into the gauge pod. I plan to put it in one of the unused holes. On the 87/88 models we have the option of the tow/turn indicator on the left gauge. Or the blank opposite of the high beam. In my case I had a spare cluster and I was able to adapt the central warning light lens to replace the blank.
Last edited by Michael Benno; 11-30-2020 at 11:42 PM.
The CEL/knock indicator will come on when the key is turned to ON, then stay lighted after startup for a few seconds. If the memory has been reset then it will stay lighted until revs are raised to ~1800. It will stay on constantly if there is a knock or hall sensor error.
To reset without disconnecting the battery hold the accelerator to the floor when turning the key to ON, then release the pedal before starting.
11-18-2020, 11:42 PM
