Haltech E6A - Manual (Page 49)

49
If the engine does not start it may be because the fuel requirements are not right. If this is the
case, it is suggested that you remove the 20Amp fuse for the fuel pump and do the timing
check while cranking. This will require two people : one to crank the engine and one to
operate the timing light. It can be difficult to check the timing accurately at cranking speeds.
Removing the spark plugs will help the engine to rotate at an even speed. Once you have
checked the timing at crank, leave the Timing Check on, skip the next section on loading an
Ignition Library Map and go to the section on Determining Engine Fuel Needs. Once you have
the engine starting and idling, return to this section, check the timing again, and then load the
Library Map.
Use an ignition timing light to check that the ignition timing is set to 10° BTDC. See the
workshop manual for your engine for details on checking ignition timing and the use of a
timing light.
The timing should be locked at 10° BTDC. If it is not then the angle at which the ECU is being
triggered is not the same as the angle in the Trigger Degrees field in the Ignition Setup. If the
timing is miles out, go back and check all the angles again. If you have guessed the trigger
angle, try and calculate it properly. Remember that the angle is in crank degrees, not distributor
degrees. Also make sure the trigger edges are correct. These can have a very large affect on
the trigger angle.
If the angle is a little out, it is just a matter of aligning up the actual trigger angle with the angle
in the Trigger Degrees field. There are a few ways to do this :
If the timing reference is taken from a distributor, then you may be able to rotate it while
using the timing light until the engine is at 10° BTDC. Be wary about adjusting the base
timing in this manner by any more than a few degrees as it can upset the rotor phasing.
For details on rotor phasing, see Appendix F.
If the reference is taken from a cam angle sensor (such as in a distributorless direct fire
engine), then if it is possible, rotate the sensor while using the timing light until the
engine is at 10° BTDC. With a cam angle sensor, there is no need to worry about rotor
phasing.
The last method is to change the Trigger Degrees field in the Ignition Setup. (See the
previous Chapter for details on how to change this field). If you are using a crank angle
sensor then this is the easiest way to adjust the base timing. The Trigger Degrees field
tells the ECU where the trigger is occurring. Once the ECU receives this trigger, it
calculates how many engine degrees to delay until it has to fire the spark. For example, if
the trigger is at 70° BTDC, and the Timing Check is on, the ECU will delay 60° and then
fire the spark at 10° BTDC. If however, the trigger was actually at 80° BTDC, but the
Trigger Degrees had a value of 70, the ECU would still delay the 60° and the engine
would fire at 20° BTDC. Changing the value of the Trigger Degrees field to 80 would
increase the delay from 60° to 70°, and the engine would now fire at 10° BTDC. When
adjusting the parameter, do so in small steps, say 5 or 10 degrees at a time. This will
allow you to check that you are moving in the right direction.