Detonation Waveform

jymmiejamz · Post by **jymmiejamz** » Sat Jan 19, 2019 7:31 pm

Does anyone have a waveform of an engine experiencing detonation? Working on a Range Rover Sport 3.0 V6 petrol that sounds like it is detonating under load. Basically sounds like a rattle under certain conditions. This vehicle had the engine replaced due to catastrophic failure. The technician that installed the engine was kind of a butcher and no longer works at our shop. The engine has been replaced a second time which did not resolve the issue. The fuel tank has been drained and filled with 91 octane fuel (highest available in California). We have verified normal operation of the knock sensors in the shop with the engine running and by tapping on the block with a hammer in comparison with another vehicle.

Basically at this point we want to confirm using the PicoScope that the engine is actually detonating and that is isn't some other component, such as the supercharger, making noise. We have not been able to isolate the noise using a chassis ear.

I don't have the waveform on me at the moment, but I can post on Monday to get everyone's thoughts if it is in fact detonation the knock sensors are picking up.

Thank you,

James

Technician · Post by **Technician** » Sun Jan 20, 2019 12:42 am

Hi James,

Scope and Chassis ear data would be nice.

victor2k · Post by **victor2k** » Sun Jan 20, 2019 2:49 pm

Hello,
I think your knock sensors signals captured by a scope and a reference will be the best option,other option is to check with a scanner the ignition advance for bank 1 and bank 2 when the knocing occur

Best regards

jymmiejamz · Post by **jymmiejamz** » Mon Jan 21, 2019 4:14 pm

The live data of the ignition advance is not a valid signal on SDD. We compared to another vehicle and found the no change in ignition advance under any conditions.

I have attached the Picoscope file.

victor2k · Post by **victor2k** » Tue Jan 22, 2019 7:44 am

Hello,
From the attached file some non-repetitive detonations can be detected on the channel a

but without a reference(ignition,cam or crank signal) is useless.
Please add more details from your engine, make some new captures using the spectrum mode/scope mode and a reference signal.Also try to record with a phone the knocking,maybe will help using NHV module

Best regards

Steve J · Post by **Steve J** » Sat Feb 02, 2019 1:15 pm

https://www.plex-tuning.com/products/pl ... k-monitor/

http://tunernerd.com/

Some swear by a simple "det can". Google it.

jymmiejamz · Post by **jymmiejamz** » Sun Apr 21, 2019 3:23 am

victor2k wrote: ↑
Tue Jan 22, 2019 7:44 am
Hello,
From the attached file some non-repetitive detonations can be detected on the channel a Capture.PNGbut without a reference(ignition,cam or crank signal) is useless.
Please add more details from your engine, make some new captures using the spectrum mode/scope mode and a reference signal.Also try to record with a phone the knocking,maybe will help using NHV module
Best regards

Sorry for such a late reply to this.

Basically there was some debate around the shop as to whether or not the noise we were hearing was in fact detonation, hence the need for a waveform of detonation

The root cause of the issue turned out to be that the connectors for the knock sensors were swapped between banks. This would have more easily been identified if we had a reference signal.

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