High RPM crank trigger setup

[jsarv03]

Been reading through previous posts about crank trigger setups and learned alot of valueable information.

My current situation is I have an engine that exceeds 10k rpms (10,600) that I am having a difficult time getting my crank trigger reliably setup.

Currently using a Honeywell LCZ360 sensor (15khz rating) I exceeded tooth sizing based on Honeywell's recommendation but still get at least one, if not more missed teeth, randomly, above 8400 rpms. The tighter I made the sensor the higher up the issue went. Originally started at 6200 rpms and as I made the sensor gap smaller (down to .010") it moved up to averaging 8400.

I have had 6-7 differently designed wheels made and tested with them, most all produce same results. 36-1 was what my goal was, but looking like 24-1 is where I will end up. Wheel diameter is 4.6" (my max size I can go) and made out of a high iron content steel.

I have not put an Oscope on it to confirm if it was a sensor or ecu error, but just looking for thoughts..

ECU is AEM Infinity 508. All wiring is shielded twisted and running 12v to sensor rather than 5v reference.

thanks!

[mrriggs]

You really should put an oscilloscope on there to see what it is doing.

Years ago I made a digital ignition controller and used a Ford EEC-III crank sensor setup to trigger it. With the oscilloscope I was able to see that the counter weights on the balancer were affecting the signal. Knowing exactly what the signal looked like made it a simple task to adjust the bias voltage so it wouldn't false-trigger the ignition.

You need to know what the trigger thresholds are on the ECU and check the sensor output with a scope to verify that you are meeting them. If that all checks out then the problem must be in the ECU itself.

[Belgian1979]

Hall or VR sensor ?

Make sure that you do not have noise. I had to do some filtering on mine. I use a 60-2 and so far had no issue up to about 7000 rpm, which is where I was so far.

[Rick Finsta]

Scoping it is the next step, IMHO. I've seen Hall sensors with a 0.040" gap run up to 17K no problems. Otherwise, can you post a picture of the wheel design? Some tooth shapes can cause issues, and imperfect spacing can be a big problem at higher RPM where trigger timing being off a small amount can look like noise to the ECU.

Also, you can check and see if your ECU has a period reject in the noise rejection settings (if it has such settings) and that may be causing problems.

[andyf]

I designed my own 36-1 wheel for a big block Mopar since nobody makes them. It works fine at higher speeds with the Holley sensor. We checked it with a scope and the signal looked great. Falling edge tends to be much cleaner than raising edge so if your ECU has the option you should trigger on the falling edge.

[Belgian1979]

I designed my own 36-1 wheel for a big block Mopar since nobody makes them. It works fine at higher speeds with the Holley sensor. We checked it with a scope and the signal looked great. Falling edge tends to be much cleaner than raising edge so if your ECU has the option you should trigger on the falling edge.

Yes, one can switch. The design of the tooth is so that it has a sharp edge at the top.

I still think this is a noise issue. Maybe put a 1K ohm resistor in between the ground and signal ?

[In-Tech]

Been reading through previous posts about crank trigger setups and learned alot of valueable information.

My current situation is I have an engine that exceeds 10k rpms (10,600) that I am having a difficult time getting my crank trigger reliably setup.

Currently using a Honeywell LCZ360 sensor (15khz rating) I exceeded tooth sizing based on Honeywell's recommendation but still get at least one, if not more missed teeth, randomly, above 8400 rpms. The tighter I made the sensor the higher up the issue went. Originally started at 6200 rpms and as I made the sensor gap smaller (down to .010") it moved up to averaging 8400.

I have had 6-7 differently designed wheels made and tested with them, most all produce same results. 36-1 was what my goal was, but looking like 24-1 is where I will end up. Wheel diameter is 4.6" (my max size I can go) and made out of a high iron content steel.

I have not put an Oscope on it to confirm if it was a sensor or ecu error, but just looking for thoughts..

ECU is AEM Infinity 508. All wiring is shielded twisted and running 12v to sensor rather than 5v reference.

thanks!

Hello,
I have not used that particular Honeywell sensor and the Honeywell's I have used worked quite well but don't disregard that it could be a "not so good sensor" .

That is a small wheel for that rpm but "it is what it is". Do you have any way to true the wheel while it is spinning and use a stone to clean up the sharp edges?

Bottom line, you really need a scope to see what is happening. Belgian mentioned a "pull down resistor circuit" Do not be afraid to try different feed voltage to the the Hall as well as pull up or pull down although that will have very little to do with "noise" but might satisfy that AEM controller. Talk with AEM as well, I have not looked deeply into their software but I would imagine there are software filters as well.

Let us know. I have one of those AEM 508's on the shelf