EDIS Cranking Timing

I read in the MegaManual that EDIS retards ignition timing to "around TDC" while cranking. According to my timing light, #1 is firing around 10deg aTDC while cranking. I'm using EDIS 6 w/ MS1v3.0, if it matters.

Anyone else check EDIS cranking timing before?

Thanks

Hmm, first I've heard of that.

I do know that the EDIS controller will default to 10 degrees as a fail safe if it doesn't receive a SAW signal from the MegaSquirt controller.

If the EDIS controller does receive an appropriate signal then it should crank at the timing you set in the table.

Here's more info on the EDIS system:

http://www.dainst.com/info/edis/edis.html

and here is the section in the megamanual you might be referring to:

megamanual said: The VR sensor and 36-1 crank trigger wheel must be set in the correct relationship to each other. With the engine at TDC for cylinder #1, this relationship is: EDIS-4: missing tooth is exactly nine teeth (90°) ahead of the VR sensor, EDIS-6: missing tooth is exactly six teeth (60°) ahead of the VR sensor, EDIS-8: missing tooth is exactly five teeth (50°) ahead of the VR sensor. Note that you have a choice where to place the sensor, IF you can shift the wheel. It is a good idea to build the VR sensor bracket so that you have a degree of radial adjustment (closer/farther from the wheel) and angular adjustment (closer/further from TDC). Also, bear in mind that most automotive engines rotate clockwise when viewed from the front, except many Honda engines. With the above configuration, the EDIS module will fire the ignition at 10° BTDC, unless the module receives a Spark Angle Word (SAW) command. The 10° advance is constant, regardless of RPM. This functions as a limp-home mode; if the module doesn't receive SAW commands from MegaSquirt-II, it will generate a usable (but not optimal) 10° BTDC of ignition advance. To test the VR sensor alignment, run the EDIS in limp home mode. This can be done by disconnecting the SAW/PIP plug, or disconnecting MegaSquirt-II (or its power). Start your engine and check that the timing is exactly 10° BTDC with a timing light on cylinder #1. If the timing isn't 10° BTDC, adjust the position of your VR sensor until the timing is as close to 10° BTDC as you can get it. Note that at very low rpms (less than 400) the EDIS with no SAW input will start at almost TDC and as rpm increases towards 400 the ignition point will approach 10° BTDC; it will be stable above that engine speed. So the engine must be running to check the timing, cranking won't work. Don't forget to reconnect the SAW/PIP plug when you are done, or you will have NO timing advance and your engine will run poorly and inefficiently. The VR sensor signal polarity is such that when the tooth tip is exactly centered on the VR sensor, the VR output is at zero volts falling from a positive to a negative polarity - i.e. a zero-crossing with a negative slope. The VR signal is fed directly into the EDIS module, to indicate the crankshaft's position. The EDIS module handles all VR signal processing. In fact, the EDIS module has a built-in VR signal hysteresis - when the VR signal is passing from negative to positive polarity (next tooth is approaching), the signal must reach +0.5 volts before the EDIS module will "arm". It then will "trigger" when the signal passes through zero on a positive to negative transition, which occurs when the VR sensor tip is aligned with the crank wheel tooth. Using the VR signal and the 'missing tooth' wheel, the EDIS module can synchronize with the engine crankshaft.

Note the bold sentences and how they talk about the interaction.

Right, right.

EDIS defaults to 10deg bTDC except when cranking. The MegaManual says cranking timing is "almost TDC", and I'm wondering if it goes as far as 10deg after TDC. That seems pretty retarded to me, but at very low speeds, it may be necessary.

I wouldn't normally care what the cranking timing is, but I can't get the engine started, and I want to know if the EDIS module is firing plugs at the right time.

Thanks for the reply.