Knock Sensore code P0325 in K2500 7.4

[WojTec]

If the KS are over torqued that could be your problem. Carbon fowled cylinders maybe, Bad wiring, Low quality fuel, Poor spark, timing. You need to eliminate everything as a possible cause.
You might not hear it, but if the New AcDelco sensors are torqued correctly and registering knocks and all else is correct, you have an engine problem.

Ok -so how to test Acdelco or NTK - if are working on the test bench Have you seen my video - all 4 are not giving me AC output more than 100-150mV - all internet is indicating over 1Volt.

 

[Schurkey]

Ok -so how to test Acdelco or NTK - if are working on the test bench Have you seen my video - all 4 are not giving me AC output more than 100-150mV - all internet is indicating over 1Volt.

I have not researched this. So what follows is merely a guess, and not an educated guess at that.

The knock sensors put out voltage, but extremely little amperage. Therefore, the input impedance of your test system will be critical.

Most all multimeters sold now have a "computer safe" input impedance of 10 megohm or more. But the difference between a 10-meg input impedance and a 20-meg input impedance is enough to show a difference in O2 sensor voltage; so it's probably enough to show a difference in knock sensor voltage.

Older voltmeters/multimeters had MUCH lower input impedance; which means they act as a short-circuit when connected to low-amperage devices. You can't test O2 sensors with them, and they can even cause damage to some circuits. What is the input impedance of your voltmeter?

 

[WojTec]

Dears
Shoot me some ideas.
Still getting the ignition retard as a part of P0325.

Sensors are new.
I got Cam Retard to 0.1deg - before noone know why was -18deg.
After timing 0 set engin sound smootheier even.
Engine has ~12bar compresssion
Spark plugs are bit red but this might be fuel additive
No loose on valvetrain - but I will still re-torque rocker arms and align them.

My sugestion:
Lifters- how to check them on car?
Flex plate - there is a inspection for 4L80?
Change oil - now I have fresh 5w40 syntetic. Flush and go back to 5w30?

 

[Schurkey]

Still getting the ignition retard as a part of P0325.

Download the service manual set for your vehicle from the links in the Sticky thread section of the Engine forum.

Follow the diagnostic procedure for that code.

Let's hope the "export" vehicles aren't that different from the domestic-sales versions.

I got Cam Retard to 0.1deg - before noone know why was -18deg.

If you're lucky, the last person to install the distributor didn't do the final adjustment.

Kinda concerned that you have a worn distributor gear or worn timing chain causing the distributor to gradually retard as the parts wear. Might wanna check those.

Engine has ~12bar compresssion

1 bar = 14.7 psi. (One BARometric pressure.)

14.7 x 12 = 176 psi. Wonderful.

No loose on valvetrain - but I will still re-torque rocker arms and align them.

Alignment is the responsibility of the pushrod guideplates. They're functionally locked in place with the screw-in rocker studs. No need to "align" them.

I wouldn't expect a need to re-torque the rocker arms, but it can't hurt to put the torque wrench on them.

Lifters- how to check them on car?

Are they noisy? If not, leave 'em alone.

Flex plate - there is a inspection for 4L80?

I'd expect a removable cover, but the viewing isn't going to be good except for the ring gear teeth. Everything else is going to be flashlights, inspection mirrors, or some sort of fiber-optic viewscope.

Change oil - now I have fresh 5w40 syntetic. Flush and go back to 5w30?

I wouldn't change oil from 5W-40 to 5W-30 unless it needed an oil/filter change anyway.