d-jet, rough when cold

[Funky d]

My d-jetronic 4.5 runs badly on startup. I got it tuned good when it's warmed up but now when it's cold is very rough.
I went through the self diagnosing thread. It tells me I should see the resistance of temp sensor 1 on ecu pin numbers 1 and 13. I have it at 1 and 10. Dose that make scene? I got nothing between 1 and 13. But when I disconnect the temp sensor, i can hear the idle change. Also, them sensor 2 checks out ok, as well as the aux. air valve.
What else should I look for?

[ctaylor738]

I don't have a wiring diagram in front of me, but you need to have the correct reading from both temp sensors at the ECU. And you need to have a boost in RPM by extra air from the aux air valve.

You might also check your fuel pressure.

[Nutz4Benz]

Temperature Sensor I

Temperature Sensor I is an ambient air temperature sensor.As the ambient air temperature decreases,the density of the air increases.As a result,the ECU must inject more fuel on a cold day than on a warm day.

Temperature Sensor I is a temperature sensitive resistor known as negative temperature coefficient thermistor (NTC). This sensor has a resistance of between 400 and 500 ohms at 50 degrees F. At 100 degrees F.,the resistance is between 150 to 200 ohms.

Temperature Sensor I actually has little effect on the operation on most D Jetronic equipped vehicles.This is because most of these cars have tens of thousands of miles on the engine and are running very rich due to this wear.The troubleshooting consequence of this is that disconnecting the air temperature sensor during the diagnostic procedure may have little effect on the way the engine runs,and in some cases it may actually improve the way it runs.

Temperature Sensor II

Temperature Sensor II is the coolant temperature sensor on water cooled engines.Like temperature sensor I, it is a NTC thermistor.The temperature of the engine is important because the intake manifold design of fuel injected engine does not permit the use of an air restictive choke.Additionally,restricting the air to enrich the engine during warm up would cause inaccurate readings from the manifold pressure sensor.The warm up choke function is therefore performed by Temperature Sensor II.

When the coolant temperature is about 50 degrees F.,the resistance of Temperature Sensor II is between 3000 and 4500 ohms.As the temperature increases to more that 120 degrees F.,the resistance drops to less than 1000 ohms.Thus the sensors work is done once the engine is warmed up.Also it must be continuously remind the ECU that the engine has warmed up.If damaged,Temperature Sensor II will not continue to partially function( such as the resistance values shifting). It will completely fail,creating an open short or ground.

An open circuit in Temperature Sensor II or the wiring leading to it will cause the engine to run extremely rich once warmed up.Symptoms would be dark smoke from the tailpipe (most noticable at idle),rough idle and poor power.Keep in mind that these same symptoms could also be caused by engine compression problems and ignition.

Should the sensor become shorted or the wiring harness grounded,the effects may not be noticable at all when the engine is warmed up.The symptoms would be more like a carburetor with the choke stuck open-rough or erratic idle,stalling or hesitation when the engine is cold and progressively running better as the engine warms up.