5.3 Ignition settings 5 SETTING UP A BASIC CONFIGURATION
• Check at tooth # = which tooth after the missing tooth to use to poll the cam sensor. Leave at 0 to check
when the missing tooth is present.
5.3.4.10 Missing tooth crank wheel and irregular cam wheel Some engines use a basic missing tooth crank
wheel with a complex cam wheel. Some of these have a hard coded ignition mode (Toyota 2JZ-VVT and Zetec
VCT), while others use the toothed wheel mode with a hard coded VVT decoder. If you do not have a hard coded
decoder, you can use the Poll Level feature to identify engine phase by finding a tooth that triggers on one engine
rotation but not on another.
To get the Poll Level settings figured out, start by setting the ignition mode to Log Crank and Cam, and make a
composite log while cranking the engine (See section 8.4.5 for an explanation of how composite logs work). This
will show both edges of both the cam and crank triggers. Here is an example from an inline 5 cylinder that originally
had a distributor wheel with 5 teeth. The engine builder wished to add a 60-2 crank wheel to support sequential
injection without making any modifications to the distributor trigger. The Poll Level mode makes this possible. Here
is a composite log showing two rotations of the engine. The blue line represents the crank sensor, and the green
line represents the cam (distributor) sensor. The red lines are not used in this test.
The first step is to identify the missing teeth, marked with red arrows in the image below. The next step is to
find a tooth in the green line that triggers on one cylinder rotation but does not trigger on the rotation before it. The
wider the tooth, the better, as it will span more crank degrees. In this example, we’ll try to poll on the first cam
pulse to arrive after the missing tooth (marked with a green arrow). Notice that the cam sensor signal is high for
the entire length of this tooth, but low for the entire duration of the tooth on the rotation before it.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 75
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