Issue with knock sensors
Nov 7, 2013 | 04:27 PM
#1
Issue with knock sensors
Been away from the LS scene for a long time, but I run into an issue with my truck that I cannot get around. So this is one of the last places I came to check.
07 Z71 5.3, rear knock sensor was broken so I fixed it, replaced both knock sensors and sensor harness while i had everything off. Drove it through 3 cycles and it came back that both rear and front were throwing codes. I changed them around again. Still threw a code. Reflashed the computer, 3 cycles later code. I had a mechanic friend hook up GM software to it and he said both sensors are working like they should and the harness is reading correctly. Only thing left he suggested was the computer itself might be an issue.
anyone have any advice or what i might be looking at?
07 Z71 5.3, rear knock sensor was broken so I fixed it, replaced both knock sensors and sensor harness while i had everything off. Drove it through 3 cycles and it came back that both rear and front were throwing codes. I changed them around again. Still threw a code. Reflashed the computer, 3 cycles later code. I had a mechanic friend hook up GM software to it and he said both sensors are working like they should and the harness is reading correctly. Only thing left he suggested was the computer itself might be an issue.
anyone have any advice or what i might be looking at?
Nov 7, 2013 | 07:14 PM
#3
x2. They need to be torque correctly or they will read wrong. Also, what code is it throwing specifically? Maybe the knock sensor is a secondary symptom of something else being wrong, and your truck is actually knocking. Ive seen a few trucks throw knock sensor codes when they had weak fuel systems.
Nov 7, 2013 | 10:06 PM
#4
i will check the torque again, and the initial code was p0332....
i really wouldn't care, but the truck has dropped into limp mode, and while i don't feel a difference in the power....the gas mileage has been cut in half
i really wouldn't care, but the truck has dropped into limp mode, and while i don't feel a difference in the power....the gas mileage has been cut in half
Nov 8, 2013 | 04:07 PM
#5
I have this same code pop up from time to time. Doesn't seem like anything is affected though when I comes up. This has been happening ever since I had my cam swap done.
ADDED:Forgot to add, my gas mileage is also horrible. Averaging about 11-12mpg where before I was 16-18.
ADDED:Forgot to add, my gas mileage is also horrible. Averaging about 11-12mpg where before I was 16-18.
Nov 9, 2013 | 12:55 AM
#6
TECH Fanatic
Joined: Feb 2009
Posts: 1,635
Likes: 1
From: Baton Rouge, LA
I have this same code pop up from time to time. Doesn't seem like anything is affected though when I comes up. This has been happening ever since I had my cam swap done.
ADDED:Forgot to add, my gas mileage is also horrible. Averaging about 11-12mpg where before I was 16-18.
ADDED:Forgot to add, my gas mileage is also horrible. Averaging about 11-12mpg where before I was 16-18.
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
The PCM determines that this signal is less than the expected amount for more than 9 seconds .
ACTION TAKEN WHEN THE DTC SETS
IMPORTANT: If the KS is dropped, the sensor must be replaced.
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 .
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.
- 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.
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
Nov 15, 2013 | 04:33 AM
#7
well, went back checked the torque specs and even put another new harness on....light still came back
on a side note, there is a valve/vacuum part that sits on top of the intake manifold throttle neck, it has a single
screw that holds it in and a hard hose that goes to the back of the engine? believe ill need to be replacing that soon also
on a side note, there is a valve/vacuum part that sits on top of the intake manifold throttle neck, it has a single
screw that holds it in and a hard hose that goes to the back of the engine? believe ill need to be replacing that soon also
Last edited by staringback05; Nov 15, 2013 at 04:49 AM.
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Nov 15, 2013 | 05:51 AM
#8
TECH Fanatic
Joined: Feb 2009
Posts: 1,635
Likes: 1
From: Baton Rouge, LA
well, went back checked the torque specs and even put another new harness on....light still came back
on a side note, there is a valve/vacuum part that sits on top of the intake manifold throttle neck, it has a single
screw that holds it in and a hard hose that goes to the back of the engine? believe ill need to be replacing that soon also
on a side note, there is a valve/vacuum part that sits on top of the intake manifold throttle neck, it has a single
screw that holds it in and a hard hose that goes to the back of the engine? believe ill need to be replacing that soon also
As far as the knock sensor goes, you may have a faulty wiring harness or a faulty PCM. You'd need a skilled mechanic with the proper tools to test that, though.
Nov 15, 2013 | 01:02 PM
#9
That doohickey is your EVAP valve. They are normally kinda loose, I haven't had issues with them causing vacuum leaks though unless they break internally.
As far as the knock sensor goes, you may have a faulty wiring harness or a faulty PCM. You'd need a skilled mechanic with the proper tools to test that, though.
As far as the knock sensor goes, you may have a faulty wiring harness or a faulty PCM. You'd need a skilled mechanic with the proper tools to test that, though.
As for the knock sensor, I plan on pulling the spark plugs to check gap and make sure none have issues. I replaced them all on a tune up about 40k miles ago with oem plugs. This is the last thing I can think of, is that I'm having a problem with detonation. Although the truck idles smooth and isn't throwing any miss codes. After I check the plugs, if that's not it, I might be dropping it off at the dealership
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