dgkula

I have a GIAC chip and upgraded DV on 2000 A4 1.8TQTip. Otherwise the car is stock.

I borrowed a friend's VAG COM to have a look at the timing out of curiosity.

I've done a few runs and, in general, timing retard is 0. However, it consistently goes up under increasing engine loads and during that time is regularly between 3 and 6.8 with occiasional spikes to 8.5.

I have no DTCs. I do have a boost leak that I have not yet resolved.

My understanding (having STFA) is that timing retard > 4 (or > 6) is bad for the engine and indicates knocking. I am running 93 octane Shell gas so I don't believe this to be the cause.

What should I look for to fix this and can this amount of timing retard cause damage to the engine?

Thanks,
David

diagnosticator1

But you are not harming the engine at 8 degrees.
The ECU, when the knock sensors detect pre-ignition or the begining of detonation, retards the timing in steps until the detected knock condition is halted. Then, advances the timing agian, in steps to find the knock limit. That knock point changes constantly with engine load, boost, a/f ratio, intake temp, rpm, etc,etc. The maximum retard is 12 degrees for knock control CF. The timing and knock CF is adjusted as needed, cylinder by cylinder, from one power stroke to the next, for each individual cylinder, independently from the other cyliders. The higher CF values, result from the reletively aggressive ignition timing profile as mapped by GAIC.

dgkula

So if I log knock sensor voltages, I should see CF when they exceed a threshold?

dgkula

Under heavy load (engine load > 100) they are spiking above background and this is when timing retard is applied.

The knock sensor voltage spikes range from:
KS1 6 - 13V
KS2 6 - 13V
KS3 4 - 8.5V
KS4 4 - 9V

I am running 93 octane gas. Is this type of knocking normal at these engine loads?

diagnosticator1

The signal from the knock sensors is filtered before evaluation by the ECU. Then, statistical methods are used to characterize the signal for use to indicate pre knock conditions. In addition, other engine parameters are included in the algorithm to identify probably knock activity. Do not use knock sensor voltage, it is only a minor part of the overall strategy for knock control.

diagnosticator1

As the purpose of the knock control strategy used by the ECU is to prevent/stop the development of knock activity. Fully developed knock and detonation at full load and high boost can cause damage in only one or a few power cycles, I.E, in fractions of a second, and is specifically avoided by intent.
"Combustion Knock", is a term used that includes several different but interrelated dynamic combustion behaviors. There is "spark knock", resulting in excess pressure rate of increase per degree of crank angle change, and "detonation", that is also an excessive rate of increase in cylinder pressure caused by secondary ignition of the fuel/air mixture at locations separate from the spark initiated flame front, usually the result of auto ignition of the fuel/air mix from pressure and temperature effects.
Excessively advanced spark timing will cause pre ignition, "spark knock" or "pinging", the effects of that will provoke detonation activity.

EdyJun

FYI: boost leak can cause high CF. Get the boost leak fixed first, then re log