944 DME

[barks944]

It seems the 944's DME only knows engine speed and when the engine is at TDC. 4 stroke means 2 crank rotations in a cycle, does that mean the 944's dme doest know which crank rotation and which stage of the cycle each piston is on? If that's the case I guess its not a problem because there is no sequential injection and the distributor makes sure the right spark plug spark at the right time. Is that correct?

 

[sawood12]

I think you're right Tom - there is a reference sensor at the top of the bell housing but that only switches on the ignition circuit upon start up, there is also a crank sensor at the bottom of the engine for some reason, but I don't think the crank position is know to a particularly fine degree. If you want to go to fully sequential injection you need to either add a toothed ring to the flywheel and a sensor on the bell housing or use a hall sensor on the cam shaft - oh and a stand alone EMS.

The Vitesse MAF kit runs semi-sequential injection by simply tieing pairs of injectors together so they fire alternately so no crank position sensing needed.

 

[944Turbo]

IIRC there are only 2 injector drivers anyway so you cannot separate them from the pairs for sequential. they may be batched fired together in the standard setup and seperatly (semi sequential) with vittesse. I have seen a number of articles that say there is very little to gain between sequential and batch firing and IIRC Rick found similar with his standalone. Suprising but maybe the 'puddle' of fuel behind the closed valve has some side benefits or is vapourised.
Tony

 

[barks944]

What type of sensor are the ref sensors on the 944? Most modern EMS talk about inductive or digital sensors, I get the impression that the 944's are neither.