I'm getting a grinding noise when I hold the revs @1000 RPMs (approx. 20=25 mph)

The knock sensor's job is to retard the ignition timing when the engine starts pinging the noise it makes is like dropping marbles in a tin can-start checking all the pulleys-could be a driven component bearing

Did that fix it thunder?

If it was a Ford I'd say the heat shield on the catalytic converter. You might check that. It's in a location that might make you think engine or tranny.

Do you hear the grinding when in park or neutral @1000RPM? Or just in gear? What about if you toss it (carefully) into neutral while driving and bring the RPM to 1000? You could have a hub or wheel bearing going out but not be able to hear it at higher speeds due to normal road noise.

The transmission shifts based upon engine speed and vehicle speed. So, holding the engine speed steady shouldn't make the transmission shift smoothly. It should just keep the vehicle speed steady, on level ground.
It sounds like you have multiple problems. The grinding sounds like a bearing.

And it sounds like your engine is experiencing pre-ignition. Does the 'marbles in a can' sound speed up when the engine speeds up?

Yes. You want transmission codes, especially. But tell the shop or parts store you need soft codes. Those won't set the CEL.

No. Codes can be soft or hard. Hard codes cause the CEL to come on or flash. Soft codes don't.

U1000= Loss of data communication
U1016=Loss of PCM data communication
P0327=Knock sensor circuit-low voltage
P0463=Fuel level sensor circuit-High voltage
P0101=MAF system performance

Because they don't have the right scanner.

How does the engine sound when it's shuddering and shaking? Have you checked for vacuum leaks?

AIR BAG RESTRAINT SYSTEMS -2000 Cadillac Seville SLS
Page 1 of 1
DTC U1000 : LOSS OF DATA COMMUNICATION

Circuit Description

When the ignition switch is in RUN position, all modules communicating on class 2 serial data line send a State of Health (SOH) message every 2 seconds to ensure that the system is operating properly.
Diagnostic Aids

Engine will not start if there is a total malfunction of the class 2 serial data line circuit.

U1016: same as above

ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.6L -2000 Cadillac Seville S.
Page 1 of 2
DTC P0327: KNOCK SENSOR CIRCUIT - LOW VOLTAGE

NOTE:
For circuit reference, see WIRING DIAGRAMS article.
Circuit Description

PCM uses Knock Sensor (KS) to detect engine detonation. KS produces an AC signal at all engine speeds and loads. PCM makes adjustments to spark timing based on amplitude and frequency of KS
signal. PCM checks the KS system by comparing actual KS signal to noise channel. A normal KS signal should switch outside of voltage range greater than or less than noise channel. DTC will set when engine
is running and PCM detects a KS signal less than 0.44 volt.
Diagnostic Procedures

Perform On-Board Diagnostic (OBD) system check. See ON
SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
Start engine. Using scan tool, monitor SPECIFIC DTC INFO for this DTC until test runs. If scan tool indicates that this DTC failed this ignition, go to step 4. If scan tool does not indicate that this
DTC failed this ignition, go to next step.
Turn ignition on, with engine off. Using scan tool, review and record fail records data. Operate vehicle within fail records conditions. Monitor SPECIFIC DTC INFO for this DTC until test runs.
If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see DIAGNOSTIC AIDS.
Using scan tool, save FREEZE FRAME & FAILURE RECORDS data stored when DTC was set. Turn ignition off. Disconnect PCM harness connector. Using a DVOM, check frequency between
KS signal and ground circuits while tapping on engine block using a non-metallic object. If DVOM displays a fluctuating frequency while tapping on block, go to step 8. If DVOM does not
display a fluctuating frequency while tapping on block, go to next step.
Disconnect knock sensor/starter solenoid harness connector, located on right side of engine compartment at rear of intake. Using a DVOM, check frequency between KS signal and ground
circuits while tapping on engine block using a non-metallic object. If DVOM displays a fluctuating frequency while tapping on block, go to step 7. If DVOM does not display a
fluctuating frequency while tapping on block, go to next step.
Check for short or open to chassis or sensor ground in KS signal circuit. Check for poor connections at knock sensor. Repair as necessary. After repairs, go to step 11. If circuit or
connections are okay, go to step 9.
7. Repair poor connections, open or short to ground between knock sensor/starter solenoid circuit and PCM. After repairs, go to step 11.
8. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 11. If connections are okay, go to step 10.
Replace knock sensor. After replacing knock sensor, go to step 11
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Turn ignition on, with engine off. Using scan tool, review and record fail records data. Operate vehicle within fail records conditions. Monitor SPECIFIC DTC INFO for this DTC until test runs.
-
BOARD DIAGNOSTIC (OBD)

1.
2.
3.
4.
5.
6.
9. 10.
.
11.

ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.6L -2000 Cadillac Seville S.
Page 2 of 2
If scan tool indicates that this DTC failed this ignition, go to step 4. If scan tool does not indicate that this DTC failed this ignition, system is okay.
Diagnostic Aids

Check for an intermittent open or short in knock sensor circuit.

ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.6L -2000 Cadillac Seville S.
Page 1 of 1
DTC P0463: FUEL LEVEL SENSOR CIRCUIT - HIGH VOLTAGE (DEVILLE & SEVILLE)

NOTE:
For circuit reference, see WIRING DIAGRAMS article.
Circuit Description

Fuel level sensor is used to determine level of fuel in tank. PCM applies ignition voltage to sensor. Sensor varies voltage based on fuel level. Resistance is high when tank is full and PCM senses high signal voltage. As fuel
level decreases, sensor resistance drops and signal voltage at PCM is pulled low. PCM uses fuel input to run certain tests, including EVAP system, misfire or oxygen sensor.
PCM also sends fuel level information via the Class II serial data to the IPC, which uses this information to control fuel gauge. PCM requires an accurate indication of fuel level for EVAP system diagnosis.
DTC will set when PCM detects a signal voltage greater than the calibrated range of the sensor for a specific length of time.
Diagnostic Procedures

Perform On-Board Diagnostic (OBD) system check. See ON
CHECK under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
Using scan tool, check for any IPC related DTCs set. If any IPC DTCs are set, diagnose affected DTC(s) first. If no IPC related DTCs are set, go to next step.
Turn ignition off. Disconnect fuel sender assembly
Observe fuel gauge. If fuel gauge indicates FULL, go to next step. If fuel gauge does not indicate FULL, go to step 5.
Leave ignition on. Connect a jumper wire between fuel level sender signal and ground circuits in harness connector. Observe fuel gauge. If fuel gauge indicates EMPTY, go to step 6. If fuel gauge does not indicate
EMPTY, diagnose instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
Check fuel level signal circuit for short to chassis ground or sensor ground. Repair as necessary. After repairs, go to step 8. If circuit is okay, go to step 7.
Replace fuel level sensor. After replacing sensor, go to step 8
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step. Using scan tool, review and record FREEZE FRAME and FAIL RECORDS data. Clear DTCs. Operate
vehicle within parameter for setting this DTC. Using scan tool, monitor SPECIFIC DTC INFO for this
DTC until test runs. If scan tool indicate that this DTC failed this ignition, go to step 2. If scan tool does not indicate that this DTC failed this ignition, system is okay.
-
BOARD DIAGNOSTIC (OBD)
SYSTEM
1.
2.
3.
Harness connector. Turn ignition on, with engine off.
4.
5.
6. 7.
8.
.
Diagnostic Aids

Always diagnose fuel level sensor before any other EVAP system components or DTCs. Do not use fuel gauge as an indication of a shorted or open circuit as IPC may always default to EMPTY or FULL depending on vehicle
model.

ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.6L -2000 Cadillac Seville S.
Page 1 of 2
DTC P0101: MAF SYSTEM PERFORMANCE

Tips Click a link to view tip
Tip: P0101 & No Symptoms
Question: massair flow connector view.
Administrator 2
Tech1
For circuit reference, see WIRING DIAGRAMS article.
NOTE:
Circuit Description

This test determines if Mass Airflow (MAF) sensor is providing proper readings to PCM. MAF sensor is a high frequency device that measures rate of airflow through throttle body. MAF sensor outputs a series
of pulses that varies in frequency with airflow. PCM uses this signal for fuel control.
MAF sensor readings during acceleration will be much higher than those during deceleration or idle. PCM calculates what MAF sensor reading should be from the sensor under certain conditions using
engine speed (RPM), throttle position, and altitude parameters. When certain test conditions are met, PCM will compare its calculated MAF value to the actual value received from the sensor. The calculated
MAF reading is calculated by comparing MAP, RPM and IAT values. If difference between calculated MAF and actual MAF is too great, DTC will set.
For duplication of DTC, ensure:
? No TP senor, MAP sensor or system voltage DTCs are set. ? System voltage is 11-18 volts.
? Canister purge duty cycle is less than or equals 90 percent. ? EGR pintle valve movement less than 90 percent.
? TP sensor angle is steady and less than 48 percent.
Diagnostic Procedures

Perform On-Board Diagnostic (OBD) system check. See ON
SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
Check if any other DTCs are set. Diagnose affected DTC(s). If no other DTC(s) are set, go step.
Check vacuum leaks at MAF sensor seal, throttle body, intake manifold, PCV, EGR system, plate or tubes and brake booster and hoses. Repair as necessary. After repairs, go to step 7. If no
problem is found, go to next step.
Check for stuck or incorrect PCV valve. Check for air (unmetered) leaks at oil dipstick tube or oil filler cap. Repair as necessary. After repairs, go to step 7. If no problem is found, go to next step.
Using FREEZE FRAME and FAILURE RECORDS data function on scan tool, duplicate conditions under which this DTC was set. If DTC resets, go to next step. If DTC does not reset,
see DIAGNOSTIC AIDS.
-
BOARD DIAGNOSTIC (OBD)

1.
2.
To next
3.
4.
5.

ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS - 4.6L -2000 Cadillac Seville S.
Page 2 of 2
6. 7.
Replace MAF sensor. After replacing sensor, go to next step.
Using scan tool, review and record fail records data. Clear DTCs. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay.
If scan tool does not indicate that this test ran and passed, repeat step 2.
Diagnostic Aids

For intermittent problem, use FREEZE FRAME data under which the DTC set, looking for faulty data from other sensors which may set this DTC. An improperly installed air cleaner or distorted intake air
duct may cause DTC to set. Check for improper air cleaner or intake air duct installation.

Yeah, it does that from time to time. The techies are working on it. I'll get the boss guy to peek in an give you the paypal address. I think it's paypal@2carpros. Com, but I'm not positive.

If you have the time and patience, those diagnostic steps are all things you can do at home. You will need a scanner, but you can rent or borrow those from most chain parts stores.

You should be able to click either the upgrade question donation button on the top of the page or the general donation button and choose your donation amount then select either PayPal or Secured Credit Card transactions. Thank you for considering us for a donation. If that doesn't work for you, our direct donation paypal address is paypal@2carpros. Com Thank You

Thanks Mike