Dan G
04-14-2003, 10:33 PM
Hello all, I'm new to the forums. Our team is eagerly preparing for the upcoming competition and is running into a snag with the crank signal.
We are running a 2001 GSX-R with a Megasquirt controlling fuel and an MSD MC4 controlling spark. The megasquirt should work fine running off the tach signal output from the MSD, so that isn't the problem. The problem is feeding the MSD an acceptable crank position sensor input.
We've hooked the stock GSX-R sensor up to a o-scope and found it to put out a spike to 12V, then it immediately spikes down to -12V, then goes back to 0. This event happens every 45 degrees, or 8 times per engine rotation.
A little digging tells us the MC4 is looking for a square wave signal. I am unsure of the duty cycle of this square wave, and I am also unsure of how many times the signal is high per rotation. From what i've heard, the MSD requires the signal to be high for "20 degress of rotation." It is not clear to me what this means. I'm curious at what crank angles the signal is high (verses #1 at TDC), and what angles it is low for an entire rotation.
Regardless, we will either need to modify our existing signal, or custom-fit a different crank position sensor with the desired output.
I've drawn up a crude paint diagram I can email to anyone if they feel they might be able to help.
MSD's tech support has been less than stellar. They won't let us talk directly to real engineers, and have been very slow to respond at all. If anyone has a good contact that I could use for my questions, I'd appreciate it greatly.
Thanks everyone,
Dan G
Carnegie Mellon University
Engine Team Leader
We are running a 2001 GSX-R with a Megasquirt controlling fuel and an MSD MC4 controlling spark. The megasquirt should work fine running off the tach signal output from the MSD, so that isn't the problem. The problem is feeding the MSD an acceptable crank position sensor input.
We've hooked the stock GSX-R sensor up to a o-scope and found it to put out a spike to 12V, then it immediately spikes down to -12V, then goes back to 0. This event happens every 45 degrees, or 8 times per engine rotation.
A little digging tells us the MC4 is looking for a square wave signal. I am unsure of the duty cycle of this square wave, and I am also unsure of how many times the signal is high per rotation. From what i've heard, the MSD requires the signal to be high for "20 degress of rotation." It is not clear to me what this means. I'm curious at what crank angles the signal is high (verses #1 at TDC), and what angles it is low for an entire rotation.
Regardless, we will either need to modify our existing signal, or custom-fit a different crank position sensor with the desired output.
I've drawn up a crude paint diagram I can email to anyone if they feel they might be able to help.
MSD's tech support has been less than stellar. They won't let us talk directly to real engineers, and have been very slow to respond at all. If anyone has a good contact that I could use for my questions, I'd appreciate it greatly.
Thanks everyone,
Dan G
Carnegie Mellon University
Engine Team Leader