Jon Schepps

Danno-
That's what I figured with respect to the timing control, and hopefully the Bosch folks made that Knock-Yes/No signal available for diagnostic purposes.
I'm going to look at that pin with a scope too, and try the "tap" test.

I'll be very interested to hear your results. If there are indeed pulses there that indicate a knock condition, it would then be very straightforward to integrate them over a short period to provide a level-of-knock indicator.

Thanks.

Jon Schepps

Although the DME/KLR schematic doesn't show any connection to pin 15 of the KLR, on looking under the connector hood, there is a blue wire in the harness that's connected to that pin. No clue where it goes to.

I checked the resistance of the knock sensor, and its in spec (300kohms).
I put a scope on the knock sensor lines, and I see a nice signal when I tap the sensor.

I tapped the wire to pin15 with a scope probe, ran the engine, and tapped the sensor - nothing on the scope.

But, I also don't get any change in idle rpm when I tap the sensor.
I get no 2-1 flash code on the diagnostic connector. (I do get the 4-1 code if I pull the TPS plug, so I know the KLR is doing something!)

But I don't know what's going on with the knock sensor, if anything.

Jon

Tom Carson

try other than idle?

Jon Schepps

Not conclusively. I would think the effect would be more noticable at idle than at higher rpm, no?

Bri Bro

I would think the KLR has several parameters that need to be met before a valid knock condition is determined. RPM and boost level come to mind. If it didn't everytime you hit the engine, it would start to stall.

cpt_koolbeenz

I'm also playing with the KLR and my trusty portable scope to see if I can shed some light on the subject.

Jon Schepps

I should also mention I've got circa 1990 APE Stage-2 chips in this car. I would hope these wouldn't disable the knock control loop for some reason. Anyone know for sure? I don't have the stock chips.

BTW, if anyone has some stock ones they want to part with, or has the EEPROM code image for burning ROMS, please let me know. Car is an '86 with K26/8.

Jon.

Tomas L

Jon, PM me.

Tomas

fast951

I'm working on application where the PiggyBack flashes an LED when knock is detected by the KLR. Similar feature will be provided with the Motronic Monitor.