Thread: 19lbs injectors + 2.7 + AFPR _ L-jetronic

AHHHHH i hate E30's srsly. the AFPR i bought doesnt work... gauge isnt working... so i put back in the stock one.. and its runing 2.5bar and turned the afm 3 clicks to lean. My car is now for sale aswell.

Technically, the fuel pressure is measured relative to the MAP. Eg, if you have 60kPa of pressure in the manifold (ie, 40kPa of vacuum) and 300kPa of fuel pressure, then your fuel pressure will actually be 360kPa absolute (or 260 gauge pressure). The aim is to always have the same pressure drop across the injectors. That way 1ms of injector pulse always equates to the same amount of fuel regardless of what the engine is doing...

i had the feeling that was the idea. otherwise every fuel pressure regulator would be a rising rate job.

Quote: Originally Posted by Waterman but the afm is registering that more air is being sucked in so the " basic calculation box " should adjust fuel accordingly... to a point. Do you think that the afm spring tension would work out conveniently enough so that you apply the above formula with spring tension increased to 1.17 *original tension? Fixed

nah, you normally set the FPR to that setting at idle it does change under vacuum to allow higher pressure, for more fuel demand hence why you see different FPR's that have are rising rate regulators, esp on turbo cars, example a 1:1 rising rate - so for every extra pound of boost pressure the fuel pressure rises 1 pound But all settings are normally done at idle

Technically, the fuel pressure is measured relative to the MAP. Eg, if you have 60kPa of pressure in the manifold (ie, 40kPa of vacuum) and 300kPa of fuel pressure, then your fuel pressure will actually be 360kPa absolute (or 260 gauge pressure). The aim is to always have the same pressure drop across the injectors. That way 1ms of injector pulse always equates to the same amount of fuel regardless of what the engine is doing...

i had the feeling that was the idea. otherwise every fuel pressure regulator would be a rising rate job.