45-60 seconds of cranking when cold. Which sensor could it be?

[sixty6falcon]

I'll get right to the problem. '84 318i, m10, manual trans. I live in Idaho and winter temps are holding steady at 25-40F. When I go to start the car in the morning, it takes me 45-60 secs of cranking with my foot to the floor before I ever get a sputter out of her.

I hear guys saying that it could be the coolant temp sensor, but which one? Bentley seems to contradict themselves when referring to which sensor is which in the coolant outlet (you know, the one with the three sensors in it).

My question is, which one of these three sensors is responsible for triggering the cold start valve?

Is it:
4) Temperature-time switch
6) Temperature sensor
8) Temperature sending unit

[browntown]

Must be a m10 thing, that wouldn't be someplace I'd look right away with a slow to crank situation.

[Wh33lhop]

It is the "24V swap" sensor activating, telling you "it's about that time."

[alpineE30]

When was the last time the fuel filter was changed and whats the fuel pressure? Also verify that the cold start is not working before changing the sensor for it, also check the wiring to it and verify its getting 12volts or whatever the voltage is, you should do more testing before putting a new sensor in. its number 4 ,for instance it could be the cold start valve itself and not the sensor or it could be clogged etc.

[bmwm42]

Have you checked your timing even if the cold start injector wasn't working a few pumps on the gas pedal should get it to come on but you would also want to check your fuel pressure as well

[sixty6falcon]

Hey guys, just wanna say thanks for the suggestions. I figured out what the problem was. I've only owned the car for about 3-4 weeks, and I suspect that the previous owner either put a new motor in it or swapped out the head cause there is some yellow markings on the valve cover. Anyway, after looking at the plug on the thermal-time switch, I noticed it used the exact same plug that the coolant temp sensor uses. I swapped them around, and with a completely cold engine it started after cranking for only 2-3 seconds. Woohoo!