bluebird71

iTrader: (53)

I was a lot more familiar with 4th gen. f-bodies before I had this truck and I figured it would be virtually the same. From my experience with those, most codes are nothing more than a light in the dash and don't really effect performance. I guess its just the opposite with these next gen. ECU's though.

N20zuki

Its 150$ for 2 knock sensors and a harness... I would just replace it all new so your not chasing a issue that may not be fixed by "used" parts.

2002 Chevy Avalanche 1500 Engine Knock Sensor Harness with Dual Connectors & Grommets at 1AAuto.com

2002-2004 Chevy Avalanche 1500 Engine Knock Sensor for V8 5.3L (8th Vin Digit T) at 1AAuto.com

bluebird71

iTrader: (53)

So I replaced the knock sensors and harness and it seemed to be ok at first, but after driving for a day it started to run like crap again and the P0327 code came back. What now?

Suburbazine

Did you make sure to torque both sensors to exactly 15ft/lbs? That code indicates poor signal from the front sensor. Did you bang it on anything?

You can disconnect the knock sensor harness and test the wires with a multimeter set to a 400mv AC hertz range. Put one lead on the front wire and the other on ground, then use a wrench to bang on the front of the engine as close to the sensor as you can. You should see a brief pulse appear on the multimeter.

CIRCUIT DESCRIPTION
The knock sensors (KS) produce an IAC signal under all engine operating conditions. The powertrain control module (PCM) calculates the average voltage range of each KS signal. If the KS system is operating normally, the PCM should monitor the KS voltage varying above and below calculated average voltage. If the PCM detects a KS 1 signal or a KS 2 signal voltage within the calculated average range, a DTC will be set. DTC P0327 refers to the front KS. DTC P0332 refers to the rear KS.

CONDITIONS FOR RUNNING THE DTC

• DTCs P0117, P0118, P0121, P0122, P0123, P0125, P1114, P1115, P1121, P1122, or P1258, are not set.
• The minimum noise level must be learned. The minimum noise level is learned when the following conditions are met:
• The engine coolant temperature (ECT) must be greater than 60°C (140°F) .
• The engine RPM is between 475-975 for 10 seconds .
• The engine speed is between 1,500-3,000 RPM .
• The manifold absolute pressure (Map) is less than 49 kPa .
• The engine coolant temperature (ECT) is more than 60°C (140°F) .
• The throttle angle is more than 0 percent .
• The engine run time is more than 10 seconds .
• The ignition voltage is more than 10 volts .

CONDITIONS FOR SETTING THE DTC
The PCM determines that this signal is less than the expected amount for more than 9 seconds .

ACTION TAKEN WHEN THE DTC SETS

• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS

IMPORTANT: If the KS is dropped, the sensor must be replaced.

• Inspect the KS for proper installation. A knock sensor that is loose or over torqued may cause the DTC to set.
• If DTCs P0327 and P0332 are set at the same time, inspect for poor connections at the KS harness jumper, located at the left rear side of the intake manifold.
• For an intermittent, refer to Intermittent Conditions. See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Strategies\Intermittent Conditions

bluebird71

iTrader: (53)

Something else is going on here. Before it threw the code it was still running very sluggish. All the spark plugs look good and plug wires are new. No indication of a blown head gasket and no misfire codes, not even in the history. My mechanic thinks its a possible coil pack or the MAF going bad but its just not bad enough to throw a specific code yet. I just think its a big coincidence its throwing the EXACT same code. I figured it would throw both if the knock sensors were really bad. He asked me if they were TRUE Denso sensors. They were Dorman and so was the harness and I have seen others on here using those just fine. Im grasping for straws at this point guys.

Suburbazine

At this point I'd say you need to get it hooked up to a datalogger like HPTuners or EFILive and get a log file of what's going on. That way a lot of people here could look at it and say "that's an issue".

Also, codes are never coincidental unless you go into the 1000-series codes, in which case they "might" be coincidental.

bluebird71

iTrader: (53)

I just realized something.....the code was originally for P0332, which is the REAR sensor. Now after changing the sensors its a P0327, which is the FRONT. This leads me to believe that it IS the sensors. DAMMIT! I may have to do this all over again! The sensors came shipped to me in a padded envelope rather than a box. They probably took a hell of a beating in shipping I'm guessing and now here I am.....

bluebird71

iTrader: (53)

Ok guys, I'm banging my head over this crap and I just want my truck to run right. My question now is, if one of the knocks sensors is bad, will it make the truck run slightly off BEFORE it even trips the CEL? The reason I ask this is because when I unplug the battery and do a relearn, it usually starts off running pretty well. Then it brings to have a VERY slight stamer in it at idle. Most wouldn't even notice it but I do because I have been paying such close attention. Then eventually it trips the CEL and the longer the CEL is on, the worse it starts to run. Will the bad knock sensor make it run worse little by little like this or are they the kind of thing that won't effect the way it runs AT ALL untill the CEL is tripped. Im just trying to make sure there isn't some hidden issue here before I go through replacing these again.

Suburbazine

Knock sensors control negative timing. When the knock sensor goes out of whack the timing will be pulled down with it. So yes, you'll see the engine running slightly crappier as time wears on as the knock retard comes into play. Once the PCM decides that the signal threshold has reached a certain point, the system goes full-retard (literally, lol).

bluebird71

iTrader: (53)

Can a vibration from say a bad trans mount cause the knock sensors to detect false knock?