nasty98vette

1998 Corvette 6 Speed. I had the clutch replaced in the car and within 10 minutes of driving down the road after leaving I got a p0332 bank 2 knock sensor code. I cleared it and it would disappear for a day or so. About a week after that I started to get HO2S codes p0171 and p0131. I replaced the rear knock sensor, it did have a cut wire, I figured it would be good to go after installing the knew sensor and harness. At the same time I went ahead and replaced both upstream 02 sensors. I put it back together pulled it out of the shop and went for a drive just for both codes to come back. The car runs like completely ****, it almost seems like its dumping fuel, I found that fuse #15 (oxygen sensors) under the hood was blown, I replaced it and still the same result. I have checked for vacuum leaks visually and with carb cleaner, I have checked the 02 sensor wiring as best I possibly could without pulling the harness from the car and visually inspecting every inch. I have monitored the 02's with a scanner and they seem to be switching correctly. I did notice at WOT they don't 0 out.

I read that there is a ground strap that is bolted down by an upper bellhousing bolt, can anyone confirm is this has anything to do with the knock sensors or possibly 02 sensors ground? It runs into the same part of the wire loom that the knock sensors run into.

nasty98vette

Any ideas?

Dcollins3208

Check out the 1st post in the link below, the first half lists the ground locations, the second half lists what is connected to each location. The o2s are grounded on the engine block on the drivers side.

https://www.corvetteforum.com/c5-tec...ml?styleid=140

nasty98vette

Thank you for that. That's something I searched for, for quite a while and couldn't find. I also might add and I will add it to the original post, if you have the lights turned off and the key on, all the lights on the car flicker. If you turn the lights on (running lights or head lights) they don't flicker and the turn signals stay solid on the instrument cluster as if they are stuck on but don't pulse just stay solid.

Dcollins3208

Hmm, I would contact Bill Curlee or 8vette7 for advice, I have no idea what's going on with your blinkers. Are the codes you listed your only codes? For the lights flickering, sounds like a loose cable somewhere, whether it be one of the grounds, battery terminals, or even the connection at the starter solenoid, the latter part being the least likely since you said it happens with key in the "on" position vehicle not started I'm assuming?

mrr23

When going WOT the o2 sensors do not zero out. They still read. The PCM uses the PE table to make fueling changes.

3boystoys

Get a scanner on it that can graph the O2 sensor output, even my cheapy $200 Actron can do that. Check the long and short term fuels trims. You may have to disconnect the battery for the fuel trims to reset and start to learn the LTFT again, had to do it with my truck after an O2 sensor change.

martysauto

P0131 will set if the bank 1 02 stays below 200mv for 33 seconds. Once it sets the ECM will go back to open loop fueling (ignores o2 sensors). It sounds like you have an intermittent short to ground on the signal circuit since you already changed the sensor.
Get your scanner on it. If you can select custom data stream, select only b1s1 sensor so it samples quicker. With sensor plugged in, key on engine off, wiggle the harness and have some monitor the reading. If it dips low, you found the cause your problem. If you can graph it, do that. You'll see it spike low.
If nothing shows up, unplug both primary sensors and road test the car. It will stay in open loop and should run fine. Monitor b1s1 while road testing and see if the voltage goes low. Post your results.

nasty98vette

Short term 02's are switching anywhere from 0.0 up to 3.4 down to -1.8 so on and so forth. They're constantly adding and subtracting all over the board. Long term's are a steady 9.4. MAF is .75

martysauto

"Short term 02's are switching anywhere from 0.0 up to 3.4 down to -1.8 so on and so forth. They're constantly adding and subtracting all over the board. Long term's are a steady 9.4. MAF is .75"

The numbers you have listed above are the fuel trims. I was referring to o2 signal voltage. Here is more info related to p0131

The PCM supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean. The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines it majority of the samples are out of the operating range.

The PCM monitors the HO2S voltage for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, a DTC will set.

Conditions for Running the DTC
DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0335, P0336, P0351, P0358, P1120, P1220, P1221, P1258, not set.
The engine coolant temperature is greater than 48°C (118°F).
The ignition voltage is greater than 9.0 volts.
The fuel system operating in Closed Loop.
The AIR and the Catalyst diagnostics are not active.
The fuel trim learn is enabled.
The air/fuel ratio is between 14.5:1 and 14.7:1. The TP angle is between 10% and 26%.
Conditions for Setting the DTC
The HO2S signal voltage remains below 200 mV
The Criteria 1 conditions are present for 33 seconds.
Action Taken When the DTC Sets
The PCM illuminates the Malfunction Indicator Lamp on the second consecutive drive trip that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.
Open Loop Fueling.
Conditions for Clearing the MIL/DTC
The PCM turns the MIL OFF after three consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed (current DTC) clears when the diagnostic runs and does not fail.
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
Use a scan tool in order to clear the MIL/DTC.

nasty98vette

I appreciate the info, the P0131 is gone for now, it cleared itself and hasn't come back yet. I'm honestly looking for a way to fake of knock sensors. Can you ground them out or put resistors in the harness to make it think they are working? The car does not have the slightest knock, tick or any noise at all that would alert them and it's causing the car to reduce power at WOT which is extremely annoying.

3boystoys

You rarely hear the knock the sensors pick up, that's why they are buried where they are.

nasty98vette

I understand that but I really think it's a wiring problem some where or another. I don't think the sensor is actually picking anything up. And based off the sounds some LS motors make that I've heard, these sensors in this car definitely shouldn't be setting a code.

nasty98vette

Bump,,,,, Still dealing with the 332 code. Can anyone verify for me if this code will send the car into reduced power mode? It makes sense to me but I want to know for sure that's what is causing the car to not have full power at WOT.

martysauto

The Knock Sensor (KS) system detects engine detonation. The PCM retards the spark timing based on the signals from the knock sensors. The knock sensors produce an AC voltage. The knock sensor voltages are an input to the PCM. The amount of AC voltage produced is proportional to the amount of knock.

An operating engine produces a normal amount of engine mechanical vibration (noise). The knock sensors produce an AC voltage signal from this noise. When an engine operates, the PCM learns the minimum and maximum frequency of the noise the engine produces. When the PCM determines that this frequency is loss than or greater than the expected amount, a knock sensor DTC will set.

Conditions for Running the DTC
Engine operating greater than 20 seconds.
ECT is greater than 70°C (158°F).
Engine speed is between 1650 and 3000 RPM.
Throttle angle is greater than the idle throttle angle.
MAP is less than 60 kPa.
Conditions for Setting the DTC
The PCM determines that this frequency is less than or greater than the expected amount for less than 3 seconds.

Action Taken When the DTC Sets
The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.
Conditions for Clearing the MIL/DTC
The PCM turns the MIL OFF after three consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed (current DTC) clears when the diagnostic runs and does not fail.
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
Use a scan tool in order to clear the MIL/DTC.
Diagnostic Aids

IMPORTANT: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.

Check the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause the DTC P0332 to set.

For an intermittent, refer to Symptoms. See: Powertrain Management\Computers and Control Systems\Testing and Inspection

Nothing above tells me it will go into reduced power mode, however if the PCM thinks it's knocking it will retard the ignition timing and power will suffer. Did you torque the new one? Was it and ac delco part? You can swap them and see if you get a p0327. If you do, your replacement is junk.
You can monitor the knock sensor signals and timing retard with a scanner.

Let us know

nasty98vette

This is a friends car so I'm just relaying information and helping where I can. Yes, the new sensor's were torqued to spec according to alldata. They were torqued to 15 ft/lbs. The jumper harness was replaced, there's no broken, frayed, smashed or burned wires. There was a smashed, frayed wire coming from one of the old sensors when we first pulled the intake to replace them but that was fixed with the replacement sensor and harness. According to the trouble tree on all data, the sensors are bad via step #4 (no signal was detected on the DMM while tapping on the engine near the sensor). I tapped all over the engine with the intake on so I couldn't get right up next to them put I did use an extension and tap on the valley cover. I just find it very hard to believe BOTH BRAND NEW SENSORS that were just put in are bad. My dad owns a shop, the shop has done hundreds of knock sensors and 99.9% of the time, two brand new sensors don't just go bad.

jbmcdonald

My Vette is a 99 with 6 speed, I believe I am having similar issues as you minus the scan codes - other then the one from yesterday - P0327 (Knock Sensor - Low Input (Bank 1) I have been going through this for 6 weeks, I have changed almost every sensor and probably checked most harnesses and wiring, ground straps under battery. I'm going to look for the ground strap you spoke of if I can get my Vette on a lift today.

Thank you - Joe

C5 Diag

I've seen your other post in the Tech section and deleted your post in "scan and tune" because it is a duplicate post ...now you said you "checked" most harnesses and wiring but how EXACTLY were they checked ??...if visually that is NOT good enough !!...this is NOT a "ground" strap problem so don't waste your time and the grounds that are near the battery have nothing to do with the knock sensors...you must know how the knock sensor circuit operates to diagnose it...did you ohm out the new knock sensor and was it torqued properly ??...that is critical...was the knock sensor harness checked between the PCM and knock sensor for an open or short ???...the OP has not been active since 2019 so I doubt he will respond.