someotherguy
+1y
Halfway there...
The temp sensor on the head is just for your dash gauge. It doesn't tell the ECM anything.
The actual CTS, coolant temperature sensor, is on the intake manifold near the thermostat housing. That's the one that tells the ECM what the coolant temp is, these usually fail in a way that makes them report colder than actual temp, causing it to run rich as shit.
Also beware you MUST use the correct temperature thermostat for a computer controlled engine, typically a 195F stat, or it won't let the engine get warm enough to go into closed loop.
FYI closed loop means the ECM is paying attention to all the sensors in order to adjust fuel mixture, timing advance, etc. whereas when the engine is cold, it's in warm-up mode - open loop - ignoring most of the sensors - rich fuel mixture, minimal amount of timing advance.
The throttle body engines really aren't hard to troubleshoot once you understand how they work, get the bugs out and they're rock solid reliable for a looooooooong time with no real maintenance needed. Best computer system ever IMO, yeah you can get more power with the 96-up Vortec engines but jeezus they're way more complicated and the parts cost a lot more.
Richard