Knock sensor replacement. 2000 454

[sewlow]

At first, when it's just starting to go away, you'll hear it knock a bit every now & then, when accelerating.
When the sensor is really dead, the truck will run fine, sorta, at lower rpms. Get a little happy on the skinny pedal & it'll cough & buck. Misfire all over. Basically just falls on it's face.

 

[Schurkey]

"I" would be looking at the scan tool to see what the knock sensor activity is.

 

[someotherguy]

And beware if you're seeing a lot of knock counts and not hearing any, one of the sensors is likely completely dead or disconnected. PCM runs a sensor test and if it can't detect knock it assumes worst case scenario and will show phantom knocks and will pull spark advance accordingly to keep the engine safe..

Richard

 

[PlayingWithTBI]

You can tell if you're getting true knocks by looking at the plugs.

https://www.dynamicefi.com/SparkPlug.php

 

[Schurkey]

OK, I gotta confess. I provided bad advice in previous posts.

My '97 K2500 has the Vortec 7.4L. I just got done removing a knock sensor to drain the block. Nothing came out. Crammed a screwdriver in the hole. Nothing but cast iron.

Duh. The knock sensors on the 7.4 aren't in contact with coolant, and they don't use the drain plug holes.

The drain plug holes are lower on the block, close to but below the knock sensor. Right side is immediately next to the engine oil dipstick tube as it comes up from the oil pan. Typical 9/16 wrenching surface, hex-head iron (or steel) pipe plugs.

I pulled the right-side block drain after re-installing the knock sensor. Coolant poured out. Pulled the left side--not as easy, the front differential, and the engine oil filter is kinda in the way--and nothing dripped. Had to poke the screwdriver into the hole to break the sediment, and then it drizzled for fifteen minutes.

On the right side, I had to install a 45-degree street elbow AFTER carving the elbow on a bench grinder so it'd clear the dipstick tube. Then installed a draincock into the street elbow. The wings on the draincock were never going to go past the dipstick tube without an elbow or a nipple or something.

A draincock will screw directly into the block on the other side.

(Edit: Photos posted below.)

 

[evilunclegrimace]

A very easy way to bench test a knock sensor is to connect a wire to the terminal on the knock sensor that has an inch or so of bare wire on the other end and ask a buddy/wife /kid to hold on to the bare wire and sharply smack the knock sensor on the bench and see the reaction of the one holding the wire. No reaction bad knock sensor, You will know if the knock sensor is good

 

[PlayingWithTBI]

She'd hit me with her meat tenderizer!

 

[evilunclegrimace]

She'd hit me with her meat tenderizer!

Make sure that ALL weapons are securely locked up AND that you do this in the garage With the main door open And that you have a clear path to the exit.

 

[PlayingWithTBI]

In other words, hit and run?

 

[texas tough]

you have to have a scanner that reads the knock counts, then u have someone tap on the block with a metallic object. my autel cp9690 reads obd1 and 2 and it reads knock counts