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View Full Version : Knock Knock, Sensor Who ?


LAF
Oct 11th, 2007, 3:05 pm
Well after the questions brought up on the knock sensor i read both the FM and Clymer. I can not find a knock sensor anywhere.

Found that you set timing with the Hall-effect and the BMW scan tool. Now there are two HALL-effect and those are mechanical in nature. In other words you adjust them to spec while tightening them down using half shims and the BMW scan tool.

So then you move on to the Motronic. The only information there is what it monitors and it adjusts based on Air temp, Intake temp, Engine temp, and O2 readings, engine load, etc.

Now is the o2 a wide band?

If the Motronic is adjusting retard and advance is it doing it with voltage reference?

Is the Motronic just building a "base" map and then just running it?

I know on my Stage II Turbo we disconnect our battery to reset our ECU to combat this condition and make the ECU relearn. We also then must retrain our Slap Stick transmission too.

Is this Motronic similar in that?

I am just wondering how the Motronic is pulling timing in a knock situation? It has to be coming off the signal from the HALL-effect but since they are mechanical, what, and how does it accomplish this.

And can the Motronic be mind bumped when setting the HALL-effect if you wanted to run the bike with more advance?

Is the Motronic just using algorithms?

Anyone help me understand this a little better?

®win
Oct 11th, 2007, 4:19 pm
The LT has no knock sensor.

Randy
Oct 11th, 2007, 4:35 pm
As far as we know the ignition mapping on the LT is pretty simple.

There is no knock sensor.

The hall devices are there to send crank position to the Motronic.

The Motronic adjusts ignition timing based upon a calculation from throttle position sensor and engine RPM. It uses the hall device pulses to determine RPM and crankshaft position. It does not deviate from that map regardless of engine temperature or air temperature. It sends the ignition pulses to the coils.

There are two maps for the fuel injection. It uses a calculation from throttle position sensor, O2 sensor and engine RPM to determine injector timing. A secondary map is used when the airbox temperature sensor passes a certain temperature.

There is some modification of the mapping as the system 'learns'. You can reset the mapping to the base map by disconnecting the battery for a half hour. You can also cause a TPS reset by disconnecting the battery for a half hour. Then turn the ignition on but do not start the bike - fully rotate the throttle from fully closed to fully open three times.

LAF
Oct 11th, 2007, 8:03 pm
The LT has no knock sensor.

I know that part..............

LAF
Oct 11th, 2007, 8:47 pm
Thank you for the reply.

So the o2 sensor is not a wide band then?

In the Clymer Page 254 it does say the Motronic is adjusting based on engine temp, intake air temp, engine speed, engine load, and exhaust gas O2 content.

"It processes this information and determines the correct amount of fuel and spark advance to provide optimal performance at all engine speeds and load conditions"

So this is why I am asking these questions.

I am coming from a Daytona Twin Tech TCFI unit on my Harley and I had full control of EVERY aspect of EFI. I also was able to log my runs to see what effect my changes had.

Just want to understand the capability's of the Motronic, and how busy or lazy it is.



As far as we know the ignition mapping on the LT is pretty simple.

There is no knock sensor.

The hall devices are there to send crank position to the Motronic.

The Motronic adjusts ignition timing based upon a calculation from throttle position sensor and engine RPM. It uses the hall device pulses to determine RPM and crankshaft position. It does not deviate from that map regardless of engine temperature or air temperature. It sends the ignition pulses to the coils.

There are two maps for the fuel injection. It uses a calculation from throttle position sensor, O2 sensor and engine RPM to determine injector timing. A secondary map is used when the airbox temperature sensor passes a certain temperature.

There is some modification of the mapping as the system 'learns'. You can reset the mapping to the base map by disconnecting the battery for a half hour. You can also cause a TPS reset by disconnecting the battery for a half hour. Then turn the ignition on but do not start the bike - fully rotate the throttle from fully closed to fully open three times.

Morley
Oct 12th, 2007, 1:52 am
Unless it is a 5 wire UEGO O2 sensor, it is a narrow band.
So all of the reports of the Motronic pulling timing with lower octane gas are false, without a knock sensor it can't know the effects of the lower octane. It may pull timing based on IAT (inlet air temp), but it would do this no matter the octane of fuel being used.

Reid
Oct 12th, 2007, 11:13 am
Great information, guys.

jzeiler
Oct 12th, 2007, 12:14 pm
So all of the reports of the Motronic pulling timing with lower octane gas are false, without a knock sensor it can't know the effects of the lower octane. It may pull timing based on IAT (inlet air temp), but it would do this no matter the octane of fuel being used.

Gee, I guess that is why the book specified premium fuel.

What ever happened to the Power Commander that was going to be available for the LT?

cfell
Oct 12th, 2007, 6:41 pm
"knock-knock... sensor"..

Sensor up, how about getting us more beer!

LAF
Oct 12th, 2007, 6:54 pm
"knock-knock... sensor"..

Sensor up, how about getting us more beer!


HEHEHEHEHEh :rotf:

Reid
Oct 13th, 2007, 10:33 am
What ever happened to the Power Commander that was going to be available for the LT?

DynoJet's response is "they have no plans to build one." Maybe if we as a group hounded them they'd see there's potential business out there.

LAF
Oct 13th, 2007, 10:41 am
DynoJet's response is "they have no plans to build one." Maybe if we as a group hounded them they'd see there's potential business out there.

That is a bummer. It would be a nice addition to the LT.

Does any other bike/car use Motronic or any flavor close?