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Tim's Auto Repair
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Experience:  Have owned a repair shop for 25 yrs.
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94 Chevy: K1500..sputter..It runs fine cold, just when its warmed up

Resolved Question:

I have a 94 Chevy Silverado K1500. It runs perfectly for the first 20-25 minutes than it begins to cough and sputter badly. It runs fine cold, just when its warmed up. Could I be running to lean or rich? My personal mechanic of 12 years has not been able to diagnose the problem in two attempts. HELP!
Submitted: 8 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 8 years ago.


this may be a bad ect[engine coolent tempeture]sensor...this tells the computer when the engine is cold so it will give the engine the more neede fuel it needs for cold start-ups...yours may be bad telling the computer that the engine is always cold,causeing it to flood out when the engine get at tempeture,,try a new ect


Description and Operation


Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant passage. Low coolant temperature produces a high resistance 100,000 ohms at -40°C (-40°F) while high temperature causes low resistance 70 ohms at 130°C (266°F).

The VCM supplies a 5 volt signal to the engine coolant temperature sensor through a resistor in the VCM and measures the voltage. The voltage will be high when the engine is cold. The voltage will be low when the engine is hot. By measuring the voltage, the VCM calculates the engine coolant temperature. Engine coolant temperature affects most systems the VCM controls.

The scan tool displays engine coolant temperature in degrees. After engine start-up, the temperature should rise steadily to about 9O°C (194°F) then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature and intake air temperature displays should be close to each other. When the VCM detects a malfunction in the Engine Coolant Temperature (ECT) sensor circuit, the following Diagnostic Trouble Code (DTC) s will set:


  • DTC P0117 circuit low.
  • DTC P0118 circuit high.
  • DTC P0125 excessive time to Closed Loop.
  • DTC P1114 circuit intermittent low.
  • DTC P1115 circuit intermittent high.

The above DTCs contain a table to check for sensor resistance values relative to temperature. Refer to Specifications / Electrical. See: Computers and Control Systems\Specificat

Component Locations
Engine, LH Side
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Expert:  Tim's Auto Repair replied 8 years ago.

the sensor may be located on the front of the intake manifold near the therastat houseing on some models


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