99 Tahoe knocking when driving
Asked by David Jan 22, 2016 at 01:23 AM about the 1999 Chevrolet Tahoe LS 4-Door 4WD
Question type: Maintenance & Repair
Have a p0305 code, replaced spark plugs, wires, distributor cap, rotor, and the control module. Knocking is getting worse. Now it shutters in idle. I'm semi mechanical. Need help.
It's a 99 Tahoe 5.7 vortec. With 196022 miles.
5 Answers
JEEP_THING answered 9 years ago
Sounds like a misfire on one or more cylinders. It would be a good idea to replace what the scanner code reads. Have u replaced any of that stuff? Especially the SPARK PLUGS! Where does it sound like the knock is coming from? Knock from motor? Knock from electrical component?
po305 is a miss fire on cylinder #5. There is a issue going on with that cylinder. I suspect the rod bearing if you say it is knocking. The sensor is picking up the delay in firing and vibration. (knock sensor) If that plug looks like it is firing and looks clean, normal, I would suspect the rod bearing.
I've replaced all those those things, it sounds like a hammer slamming the motor. And starts when rpm gets to 1.5k
Either crank bearings or check the torque converter bolts. Something spinning causing the noise.
A misfire shouldn't make knocking noises. You got bigger issues.
