Regarding the use of D-Jet in a turbo application...
Jeff Shyu's done it, and his setup works. But I think that Jeff would agree with me that it's done by using a LOT of fuel pressure and load-dependent supply (via the RRFPR and a hotwired CSV). I don't know what boost levels Jeff has been able to get to - Jeff?
If you're set on keeping D-Jet, I'd suggest taking a modest approach that requires only one modification to the system. Assuming you're turboing a stock 2.0L or 1.7L, and keeping the boost to 5 psig or less, all that you need to do is provide the proper reference pressure to the MPS for positive manifold pressure operation and full-load operation.
The problem is that the MPS will interpret the transition to positive manifold pressure as full-load, and will provide no additional enrichment. As a result, you'll get a rich surge when still not on full boost, and a progressively leaner mixture as boost builts. Not what you want.
To fix this problem, you need to provide the correct reference pressure to the vent side of the full-load diaphragm. Tap in a fitting on the throttle body above the throttle plate to supply the reference pressure. Remove the MPS, and using a drill press for precision, drill a hole in the vent end of the unit, next to the riser for the full-load stop screw. Be careful - too deep and you'll damage the full-load diaphragm below.
Tap the hole and insert a fitting. Use epoxy to seal the vent holes on the end of the case. Connect a hose from the throttle body fitting to the vent end fitting on the MPS.
Now, when the manifold pressure goes positive, it will still be lower than the reference pressure and the full-load diaphragm will not activate. This will also extend the range of part-load operation. The onset of full-load diaphragm engagement will occur when the pressure differential between the manifold and the reference pressure fitting drops below 6 in. Hg.
Due to the limited range of armature throw in the MPS, this modification will only work for boost pressures of about 5 psig or less. Beyond that boost, the MPS armature will reach the mechanical limit of its movement before the full-load diaphragm is fully engaged and you will have a lean mixture at full and eventually, part-load.
Re-adjusting the MPS part-load screw to a leaner setting to extend the range of operation to support higher boost levels will not work. Even if you compensate for the leaner mixture by increasing the fuel pressure or by adding ballast resistance to the TS2 sensor, the problem is that the MPS is already fairly close to the other end of its mechanical limit of armature movement when at about 18 in. Hg of manifold vacuum, a typical level at idle for a newer engine. You will quickly run into problems with the idle mixture being too rich for the correct part-load mixture. You can compensate somewhat by using the ECU knob to adjust, but as the transition from idle to part-load operation will be unaffected, an on-throttle "bog" is likely to result.
Happy experimenting .....
