560SEL hard start /rough idle
I am diagnosing this problem and have been through the search facility etc to determine next steps. I am getting closer but at a dead end for now. This is an 86 126/117 US version. I have been though the normal parts swapping to no change to the problem including- OVP relay,fuel pump relay,cold start injector, etc.
I am now looking at the EZL interraction with the coolant sensor which on start up as i understand defines timing based on the map in the EZL and sensor resistance. The sensor is working fine based on the resistance/temp table in the SM. When I unplug the sensor (2 pole version) both sides -- the car starts much better but then idles very rough. I also observe that disconnecting while running shuts off the air pump.
A real concern -pin 21 on my connector for the CIS control unit is unused (ie there is no cable using that pin) -- which according to the manual shoudl be the coolant temp sensor ???
Any thoughts on next steps would be appreciated.