F456M
Member
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- 127
Hi Arvid. Interesting to read about your "journey". I helped a Norwegian Spyder III owner many years ago. More or less the same problem. People had been ajusting things. Idle went up and down and too high. I testdrove the car. First thing I noticed, was that when engine breaking downhill, the engine did not brake with fuel cut off like my own 222 4v. Biturbo. But instead I could hear some small explostions in the exhaust (like an old carburator Biturbo with no fuel cut off). The early fuel injection Biturbos had fuel cut off at zero throttle until it resched a low 1500 rpm. The throttle body stop screw (adjusting the butterfly opening) was not far enough OUT. The butterfly should be closing almost completely. When the butterfly is all the way closed, the Throttle position sensor shall be adjusted so that it is in its end position ("zero throttle"). There is also one air bypass screw where you can adjust the "blow by" or "leak" when the butterfly is closed. The ECU needs to understand thst the throttle is closed to engage the idle air control / speed valve. Which should continiously adjust the right amount of air. The MAP sensor monitors the manifuld vacuum or pressure and will correct the amount of fuel to the injectors relative to the rpms and high/low engine load. That means if the throttle is too open or the bypass canal and screw give too much "natural air", the flow through the idle air control (electronic solenoid valve) is too small and it will not work properly. I attach two pics of my 1991 222 4v. that I should bnever have sold in 2005.
Erik
Nesøya
Erik
Nesøya
