94 c1500 4.3 4l60e.
truck is having trouble with breaking up between 2nd and 3rd and just generally a no power issue when at operating temperature.
new egr, knock sensor, and o2 sensor. plugs are all clean light brown.
unplugged the coolant temperature sensor and is running fine. shifts properly and no miss.
set a #15 and a #42 code.
the cts ohms out good and the timing is set at 0. so, i'm thinking the cts and is breaking down at op temp.
going to replace cts and clear codes.
is there anything else that it could be??

 

The ECT sensor problems are often in the wiring. Maybe there's a break inside the electrical connector. Take the connector off and make sure there's 5V on one wire with key on and ground potential on the other wire?

 

thanx for the quick reply
ground and hot in plug 5.01v.
batt ground and hot plug 5.06v

 

You've checked the resistance across the ECT sensor and it's within spec. (range 177Ω-100kΩ, higher the temperature, lower the resistance)? If so, you probably want to concentrate on code 42 (ignition control circuits, open or short to ground). I guess (all I can do without the hep of a scanner) things settled down once you disconnected the ECT sensor because it then kicked out of the closed-loop operation. Certain default parameters come into play when in open-loop.

 

the code 42 didn't show until i disconnected the cts.

 

not good at reading ohms. are you thinking bad coolant temp sensor????

 

I really cannot say one way or another based on what you've posted so far. However, it's not that difficult to sanity-check the ECT circuit. After the engine is warmed up enough for the thermostat to open, take the electrical connector off the sensor and then measure the resistance across the sensor terminals. It should be around 300Ω. While you're at it, measure the voltage across the electrical connector with key on to make sure of 5V. Try flexing the wires as well. Sometimes wires can have intermittent breaks inside. The following is the ECT resistance chart:

 

the readings are bouncing all over the place. voltage is good.
just gonna get a new cts and see what happens .
thanx for the help

 

sounds like bad sensor

 

ITs very nice here this news about cts sensor .

Maruti Swift