Mal-combustion when engine warms-up?

[Mr. P.]

What does it mean when you start getting KR as the motor warms-up? The tune in my truck runs well and makes really good power when the motor is cold (ECT < 160-degrees), but when it gets closer to operating temp it starts producing KR at higher load (WOT). Do I need to 'tame' ignition timing in the higher-load cells of the spark timing table, or do I need to leave them alone and work on some ECT-related offset table???

Mr. P. )

[Taz]

The octane of the fuel used, intake air temperature, engine coolant temperature, cylinder head temperature, camshaft profile, compression ratio, weight of the vehicle, gearing, and driving pattern all contribute to the "knock threshold" of the engine.

Sounds like a reduction of the ignition timing is in order - or an upgrade to higher octane fuel.


Regards,
Taz

[joecar]

What Taz said.

Also, check for carbon deposits, oil ingestion, spark plug condition.