Got Knock

[purrvert]

but don't know where from. This is sixth gear roll on, first time no knock, second time 9 deg of knock. Burst knock reports 0, dynamic noise level counts are well below the 245 set point. What else triggers knock??

[Blacky]

I'm not sure why the ESC1DNL and ESC2DNL values are flat-lining.
I believe they should be constantly changing, (unless min'd or max'd out) based on detected noise. If detected noise is above their current value they should be increasing, if detected noise is below their current value they should be decreasing.
Do you have any trouble codes? (even not related to spark, even if the MIL is switched off).

Paul

[purrvert]

They are normally very active. Scanning in dynamic mode. No DTC.

[mistermike]

I would expect quite a bit of knock going WOT in sixth at low RPM. The motor is complaining.

[purrvert]

I would expect quite a bit of knock going WOT in sixth at low RPM. The motor is complaining.

I've been trying to find what's causing knock and this is the most dramatic way to demonstrate. My noise level sensors are low and no burst indicated. Normally happens at tip in around 1200 to 1600, in First.

[mistermike]

Did you try whacking burst knock altogether?

[purrvert]

Did you try whacking burst knock altogether?

No, the aim of this excercise is to get a report of what is causing the knock. I'm having knock retard without high noise sensor levels, or reported burst knock. Before I tie in the Wideband and tune I would like to have accurate reporting. I don't show dramatic changes in airflow, at least not past the set parameters. I'm suspecting pinched wires to the knock sensors but then I should get a DTC.

[joecar]

Summary of your conditions:
a. Engine speed 995 rpm (barely off idle),
b. TPS 100%
c. MAP 101 kPa (high load),
d. IAT 44*C, 111*F (hot air),
e. in 6th gear (high load).

Engine would be expected to knock under these high load conditions;
you have significant KR for the whole time that TPS is at 100%.

Isn't 6th gear too low for less than 90 MPH...?

Some of the possible causes of knock:
a. fuel octane rating low,
b. ignition timing too advanced,
c. AFR too lean (VE and MAF tables not dialled in),
d. intake air too hot,
e. engine coolant too hot,
f. spark plugs too hot,
g. excessive oil drawn thru PCV,
h. compression ratio too high.

[purrvert]

Summary of your conditions:
a. Engine speed 995 rpm (barely off idle),
b. TPS 100%
c. MAP 101 kPa (high load),
d. IAT 44*C, 111*F (hot air),
e. in 6th gear (high load).

Engine would be expected to knock under these high load conditions;
you have significant KR for the whole time that TPS is at 100%.

Isn't 6th gear too low for less than 90 MPH...?

Some of the possible causes of knock:
a. fuel octane rating low,
b. ignition timing too advanced,
c. AFR too lean (VE and MAF tables not dialled in),
d. intake air too hot,
e. engine coolant too hot,
f. spark plugs too hot,
g. excessive oil drawn thru PCV,
h. compression ratio too high.


Yes. that's understood. This knock was expected, purposely induced. My problem is that it is not shown as noise level or burst knock. No DTC's for knock sensors, no excessive noise level, no spike for burst knock. All I'm looking for is when it knocks is an indication of noise or burst and right now I'm seeing neither. The amazing aspect of this is that my first attempt had no knock.

[joecar]

:oops: oh, I'm sorry, I completely missed your point.

[purrvert]

I'm not sure why the ESC1DNL and ESC2DNL values are flat-lining.
I believe they should be constantly changing, (unless min'd or max'd out) based on detected noise. If detected noise is above their current value they should be increasing, if detected noise is below their current value they should be decreasing.
Do you have any trouble codes? (even not related to spark, even if the MIL is switched off).

Paul

With a 2000 C5 I assume we are using the Knock-Old tables. If so, the PCM only processes signals in a certain center frequency range, I guess the PCM ignores all others and flatlines. Don't see a way in EFILive to see raw data. But my question is when there is knock how do you differentiate between noise or burst when neither is reporting?

[Blacky]

I'm still trying to figure out why they are flatlining. I don't think they should if everything is working correctly. If and when I figure anything out, I'll let you know.

Paul

[purrvert]

Is there anything else to be logged besides Knock Sensors or Burst Knock when looking for Knock Retard cause?