mirror of https://github.com/speeduino/wiki.js.git
78 lines
2.8 KiB
Markdown
78 lines
2.8 KiB
Markdown
|
---
|
||
|
title: Missing Tooth
|
||
|
description: Information about the missing tooth decoder pattern
|
||
|
published: true
|
||
|
date: 2020-01-06T00:30:19.884Z
|
||
|
tags:
|
||
|
---
|
||
|
|
||
|
# Missing Tooth Pattern
|
||
|
## Overview
|
||
|
|
||
|
A missing tooth crank trigger is used as standard equipment by a number
|
||
|
of OEMs, most notably Ford, but is also very popular as an aftermarket
|
||
|
fitment.
|
||
|
|
||
|
It is comprised of crank wheel with a given number of evenly spaced
|
||
|
teeth, and one or more 'missing' teeth. Common values are typically
|
||
|
60-2, 36-1, 24-1, 12-1 and 4-1 where the first number represents the
|
||
|
total number of teeth the wheel would have if there were none missing.
|
||
|
The second number after a dash "-" indicates the number of teeth
|
||
|
missing.
|
||
|
|
||
|
*Note: If there is a third number (e.g., 36-1-1), the missing teeth are
|
||
|
not sequential, and this decoder does not apply. Do not confuse counts
|
||
|
with slashes "/", as numbers following slashes represent cam teeth—not
|
||
|
missing teeth. Wheels with "+" indicate added teeth rather than missing,
|
||
|
and again this decoder does not apply.*
|
||
|
|
||
|
## Applications
|
||
|
|
||
|
Missing tooth crank wheels can be used on virtually any engine and is
|
||
|
one of the more popular aftermarket options. It provides very good
|
||
|
resolution in the higher tooth count versions (Eg 36-1 and 60-2) without
|
||
|
being CPU intensive to decode.
|
||
|
|
||
|
## Tuner Studio Configuration
|
||
|
|
||
|
<center>
|
||
|
|
||
|
<img src="https://raw.githubusercontent.com/speeduino/wiki/master/decoders/missingtooth_triggerconfig.png" />
|
||
|
|
||
|
</center>
|
||
|
|
||
|
Fields:
|
||
|
|
||
|
- Primary base teeth: This is the number of teeth the wheel would have
|
||
|
if there were none missing. Eg a 36-1 wheel has only 35 actual
|
||
|
teeth, but you would enter 36 into this field.
|
||
|
- Missing Teeth: The size of the 'gap' in the number of teeth. These
|
||
|
missing teeth must be situated in a single block (ie there's only a
|
||
|
single gap in the teeth
|
||
|
- Trigger Angle: This is the angle in crank degrees **AFTER** TDC
|
||
|
(ATDC) of the first tooth following the gap
|
||
|
|
||
|
### Timing Setting
|
||
|
|
||
|
The trigger angle can be found by placing the engine at TDC, then
|
||
|
calculating how far it must be rotated until the first tooth after the
|
||
|
gap reaches the sensor.
|
||
|
|
||
|
### Sequential operation
|
||
|
|
||
|
The missing tooth decoder supports sequential operation if an additional
|
||
|
cam input is present. If Sequential mode is selected for either the fuel
|
||
|
timing or spark timing, the system will expect to see a cam signal and
|
||
|
will not sync correctly without this. Note that this is ONLY the case if
|
||
|
sequential is selected for one or both of fuel and spark timing.
|
||
|
|
||
|
This cam signal should take the form of a single pulse every complete
|
||
|
cycle. This can be a short tooth or a half moon type arrangement,
|
||
|
provided that electrically there is only a single rising (or falling)
|
||
|
pulse per cycle.
|
||
|
|
||
|
## Trigger Pattern
|
||
|
|
||
|
<img src="https://raw.githubusercontent.com/speeduino/wiki/master/decoders/missingtooth_trace1.png" width="100%" />
|
||
|
|