I am setting up a new MJ install. Engine starts and sits at 10 degrees BTDC. I can see the RPM / ignition advance on the laptop (so I'm assuming that the PIP is OK) - but spark stays at locked at 10 degrees regardless of RPM or ignition advance in the cell.
I didn't have a scope but verified continuity from MJ to EDIS and then looked at the SAW with DMM in AC mode. Getting .5 to .6 VAC on the meter, seems high but I was tweaking the advance at idle to see if it moved the timing light.
Bringing home a scope from work today to see if I can see the SAW signal but let me know if anything else I missed.
Setup is an EDIS4 with new module / coil pack / VR sensor. The only thing used was the EDIS 4 pigtail (it still has the jumper on the SAW line too).
Oh yeah, MJ is the TPS flavor but I'm not running TPS just yet - I'm just tweaking the cells that it thinks the TPS is at, I'd be happy with it just running with advance.
Going to look at the SAW line tonight and see if I can source another EDIS 4 - but any other ideas appreciated.
thanks!
Troubleshooting SAW signal
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kendall_jones
- Posts: 2
- Joined: Mon Jul 18, 2022 1:02 pm
Re: Troubleshooting SAW signal
As a quick update - I did change out the EDIS module with no change (both were new).
I grabbed a scope from work & verified there was a square wave on the SAW line, but I did not dig too far into it - it did not look like the square wave duration was changing with RPM so I dont know whats missing. I did not have the TPS hooked up but was just changing timing in the "active" row - even while idling I was changing the timing in that cell and it stayed at 10D BTDC.
I had a race to make so I just added a second VR sensor set at 35 degrees and DPDT switch for 10 and 35 degrees.
I'll fool around with this later - probably on a bench so I can set up a scope to look at PIP and SAW
I know this is not a super active section of the forum but I'll update as I find out more.
I grabbed a scope from work & verified there was a square wave on the SAW line, but I did not dig too far into it - it did not look like the square wave duration was changing with RPM so I dont know whats missing. I did not have the TPS hooked up but was just changing timing in the "active" row - even while idling I was changing the timing in that cell and it stayed at 10D BTDC.
I had a race to make so I just added a second VR sensor set at 35 degrees and DPDT switch for 10 and 35 degrees.
I'll fool around with this later - probably on a bench so I can set up a scope to look at PIP and SAW
I know this is not a super active section of the forum but I'll update as I find out more.
Re: Troubleshooting SAW signal
Hi,
With the software look to see what the current ignition advance is set to. If the number is changing in the software, then the pulse width of the SAW pulse should also change. Using a 'scope is a good idea.
With the software look to see what the current ignition advance is set to. If the number is changing in the software, then the pulse width of the SAW pulse should also change. Using a 'scope is a good idea.