testing crank position sensor?

[Linc97]

Is there a test to find out if my CPS is bad. My car has moments of cranking but not starting . It doesnt happen every time and mostly if its sat outside in the cold for a few hours. all night in the garage or just driving it, and it starts fine. CPS = Crank Position Sensor.

$33 online parts store.

 

[cougarmandan]

I have been told that there is way to test a crank sensor but it needs to be connected to the car and you have to have a factory tach. If you have any kind of reading when cranking with the starter, all be it just a few hundred rpm, then your crank sensor it working. Its an old Thunderbird/Cougar SC trick because they have a damper problem that takes out the crank sensor. If you have no reading, then you aren't getting crank signal, simple as that. If you don't have a factory tach, then I don't know. I know this works on the 89 to mid 90's Thunderbird SC and I would assume it would work for 4.6 as well, but I don't know for sure. Has anyone done this before on the 4.6L?

 

[cougarmandan]

I was thinking about your situation and I thought I might also note that the crank sensor is rarely a problem. More likely causes would be a dirty mass airflow sensor, usually from running a K&N or other high performance oiled air filer, or also the IAC (idle air controller). Then you get into stuff like fuel pressure regulator or pump, and TPS (throttle position sensor). If it were me I would take the MAF meter off and clean it with some throtlebody cleaner. It only cost for the can of cleaner. One time I got some bad (dirty) gas which plugged up the fuel filter and caused all kinds of pressure problems. I thought it was pressure regulator, but it wound of being the high dollar aftermarket fuel pump that would lose it fuel pressure intermittently due a sticky check valve, I'm sure due to all the sediment in the lines and tank.