First post, first question - crank trigger

[Volvo850r]

As this is my first post i would like to start by saying hello to everyone.

Am currently in the process of looking to install a vems ecu on to my volvo 850r project car. I have remapped my std ecu would good results (from 240bhp to about 285bhp) but am looking to move to a "total" tuning solution with the aim to putting a 500bhp engine into the car.

I have been reading through the vems manuals and studying info from volvo about my engine.

My first question is about the crank trigger\rpm sensor.

The vems manual says:

It is very important that the 'TDC after the trigger' value is configured correctly. The value of 'TDC after the trigger' must be between 40 and 60 degrees. Before attempting to configure it the two values 'Trigger tooth' and 'Next trigger tooth' must be determined and configured properly, unless a coil-type trigger wheel is used.

however the data from volvo states:

Description
The periphery of the flywheel/carrier plate is provided with a series of holes. As it passes, each hole induces a voltage in the pick–up coil of the RPM sensor. The passage of several holes generates an A/C signal whose frequency is a function of the number of holes passing per second and whose voltage can vary between 0.1 V and 55 V, depending on the engine speed (RPM) and temperature. The voltage increases with RPM and temperature, while the frequency also increases with RPM. The ECM determines the RPM and angular position of the crankshaft by detecting the voltage pulses.
The pitch between two of the holes at a position corresponding to 90° before TDC is greater. The voltage pulses are interrupted as this point passes the sensor, enabling the ECM to determine the angular position of the crankshaft.
The engine will stop if the signals from the sensor to the ECM are lost.

so according to vems manual i would have to move the flywheel (60-2) as im not within range?

The engine is a 5cyl some i would assume 72 deg between each TDC, so im not quite sure how volvo have stated there is a 90 degrees gap? as i would assume the next tdc would be 18 degress after the missing teeth (90 degrees - 72 degrees).

Any help appreciated.
Matt.

[PeepPaadam]

No, the recommended TDC after the trigger position is 40-60 degrees. VEMS reads as much as 127 degrees before the TDC.

[rob@vems.co.uk]

The missing tooth is not the trigger tooth, you can define any tooth (within reason) as the trigger tooth, the optium is 90 to 60 deg BTDC.
So you pick the tooth nearest to the optimum.  You then 'fine tune' the trigger with the deg before TDC value.

We have a working Volvo 5 cylinder setup for the stock trigger so you'd not need to concern yourself too much with it in the first instance, once you see it in action you'll get a clear idea.