Backfire from the exhaust after it warms up to the operating temperature

1996 CHEVROLET TRUCK
150,000 MILES • 5.7L • V8 • 4WD • MANUAL
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RYANMRAMEY
  • MEMBER
  • 1 POST
i have changed heads, fuel pump, lifters, distributor, plugs, wires, injectors, all electrical components and all sensors. it backfires from the exhaust and starts missing and it will not start back until it cools back off.
Feb 28, 2019 at 3:33 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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JACOBANDNICKOLAS
  • CAR REPAIR CONTRIBUTOR
  • 110,190 POSTS
Hi,

Have you retrieved diagnostic trouble codes? Also, what you described sounds like a bad crankshaft position sensor. They can fail when they get hot and then start working when it cools off. Was that replaced?

If you haven't already, check to see if there are trouble codes. Here is a quick video showing how it's done:

https://youtu.be/InIlnsjOVFA

Also, here are directions for replacing the crankshaft position sensor (if you haven't already done it.

1997 Chevy Truck K 1500 Truck 4WD V8-5.7L VIN R
Crankshaft Position Sensor Replacement
Vehicle Powertrain Management Sensors and Switches - Powertrain Management Sensors and Switches - Computers and Control Systems Crankshaft Position Sensor Service and Repair Procedures Crankshaft Position Sensor Replacement
CRANKSHAFT POSITION SENSOR REPLACEMENT

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pic 2


pic 3



REMOVAL PROCEDURE
1. Remove the electrical connector.
2. Remove the sensor hold down bolt.
3. Remove the sensor from the timing cover.

NOTE: When installing or removing a crankshaft position (CKP) sensor make sure the sensor is fully seated and held stationary in the front cover before torquing the hold down bolt into the front cover. A sensor which is not seated may result in erratic operation and lead to the setting of false codes.

4. Inspect the sensor O-ring for wear, cracks or leakage. Replace if necessary. Lube the new O-ring with clean engine oil before installing.

INSTALLATION PROCEDURE

NOTE: Make certain that the Crankshaft Position (CKP) sensor mounting surfaces are clean and free of burrs before installing the CKP sensor.

1. Install the sensor into the timing cover.
2. Install the sensor hold down bolt.

Tighten
^ Tighten the hold down bolt to 8 Nm (71 lb in).

3. Install the electrical connector.

_______________________

Let me know if that helps or if it was already done.

Take care,
Joe
Dec 8, 2020 at 4:55 PM
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