1989 740 110k miles

I just recently towed, and dropped off my 1989 740 at a winter condo in Arizona.

Before I left TX, the engine started and ran flawlessly COLD or HOT (HOT being 100+ in Texas, and the same in AZ).

Now, the car still starts well COLD, but in order to start it HOT, I have to depress the throttle, and after maybe 2 or 3 seconds it will start, but runs roughly for another second or two, then runs just fine.

I've read the FAQs and a lot of threads in searches, and I'm wondering if it could be the Engine Temp Sensor mounted under the #3 runner of the intake manifold.

Unfortunately, I am not where the car is now to test this theory, so am asking for experiences from other owners about this ECT sensor theory. This is so when I head back to the car in October, I can have the proper tools and parts to carry with me. I understand that the sensor is almost impossible to remove w/o removing the intake manifold, or by breaking the electrical connector off the top of the sensor to enable getting a socket, or box end wrench over it.

Any opinions of whether this is the "Prime Suspect", and what tools to bring and the easiest way to get at the ECT sensor from those having done it would be much appreciated.

BTW, I now occasionally get a "Check Engine" light on start that usually goes out in a few seconds, or if I shut down and re-start that I never got previously. I have an OBD II scanner, but not one to read whatever that CEL may be saying. I'm wondering if this could be related.

Bob

I copied this chart to test for voltage at the ECU connector (ignition on), or resistance (ignition off).

ECT resistance cold for LH2.4 systems should be around 6k ohms at 32 degrees F (0 deg C), 2300-2700 ohms at 68 degrees F (20 C), and 200 at 212 F (100 C).

However, try checking your ECT wiring: Between pins 13 and 5 at the LH ECU (with sensor DISconnected) resistance should be infinite.

Voltage with the ignition ON and sensor connected, measured between pins 13 and 5, should be:
0 C=around 3 volts +/-.5v
20C=around 2 volts +/- .5v
100C=around .3 volt +/- .1v