2 questions for tweaking/logging braintrust....

[PSmalls::DoggieStyle]

1.) Are WOT 02 voltages used to calculate things such as CFs? I was under the impression that they weren't and therefore a bad 02 sensor didn't affect WOT performance much, if at all. I'm just looking for confirmation I guess.

2.) If KVs are high and CFs are low, does that mean the knock sensors are picking up noise that isn't in the correct frequency range to cause correction?

[E Vader]

...you will see that is suggests a direct relationship between KSVs and CFs (with KSVs determining the CFs). After much logging and tweaking I have not found this relationship to be perfectly linear. However, by utilizing fueling (stock narrow bands do not accurately show fueled conditions) you can wett the burn and reduce KSVs and inturn reduce CFs.

As you know running the car pig rich (no pun intended) will not provide for the optimal power condition. 12.5 A/F seems to be the sweet spot for the S4 as I have experienced while tweaking on the dyno.

KRS4s car gained over 27whp and 35wtq on the dyno after bringing the car to 12.5 A/F for a sustained period across previously righ/lean rpm ranges.

[Ochlockonee]

chambers, which in turn can affect CFs by raising or lowering KVs.

2)I used to be of the opinion that knock sensor noise is finely sifted through by the ecu to look for noise, so logging KSVs is a waste of time. I still believe in the filtering thing, but now think that if a given vehicle is making more knock noise than usual, then it is probably due to more knock so it pays to get used to looking as knock voltage on your car if you tweak/log
Some tuners also raise the knock threshold in their software so you may be seeing higher knock voltage on some software than others. Stock and APR software don't have much toleration for knock sensor noise. In addition to that, a properly tuned car should allow for more knock voltage as RPMs increase since the engine naturally makes more noise in many frequency ranges at higher speeds.

[Snow Trooper]

simple, informative, to the point and backed up with personal experiance...... not some keyboard t00ner. want to help me figure out theis dual bosch maf crap?

[Ochlockonee]

[EdyJun]

one is connected to another. please read. i know it's a bit long.



Pre-ignition

Defined as:
"..ignition of the air/fuel mixture before the pre-set ignition timing mark"

• Caused by hot spots in the combustion chamber. Can be caused (or amplified) by over advanced timing, too hot a spark plug, low octane fuel, lean air/fuel mixture, too high compression, or insufficient engine cooling

• A change to a higher octane fuel, a colder plug, richer fuel mixture, or lower compression may be in order

• You may also want to retard ignition timing ( *******Audi ECU uses Ignition Timing Retard - Audi ECU uses Pre-ignition to determent Correction Factor ) , and check vehicle's cooling system

• Pre-ignition usually leads to detonation; pre-ignition an detonation are two separate events


Detonation

• The spark plug's worst enemy! (Besides fouling)

• Can break insulators or break off ground electrodes

• Pre-ignition most often leads to detonation

• Plug tip temperatures can spike to over 3000°F (5,432 degree Fahrenheit) during the combustion process (in a racing engine)

• Most frequently caused by hot spots in the combustion chamber. Hot spots will allow the air/fuel mixture to pre-ignite. As the piston is being forced upward by mechanical action of the connecting rod, the pre-ignited explosion will try to force the piston downward. If the piston can't go up (because of the force of the premature explosion) and it can't go down (because of the upward motion of the connecting rod), the piston will rattle from side to side. The resulting shock wave causes an audible pinging sound. This is Detonation. (*****Audi ECU calls it Knock Voltage - more audible pinging (Detonation) the higher the Knock Voltage.)

• Most of the damage than an engine sustains when "detonating" is from excessive heat

• The spark plug is damaged by both the elevated temperatures and the accompanying shock wave, or concussion

Edy

[Ochlockonee]

Modern knock sensors measure a wide band of noise-a much wider spectrum than the noise made by a particular engine's knock. Each engine has it's own knock frequency, but it is much cheaper to make a sensor that measured a whole lot of noise, then leave it up to the powertrain engineers to filter out all the noise that does not have anything to do with an actual knock event.

• Check out this post, and check the link- it's informative

[Ochlockonee]

• Look at the spectrograph image

[PSmalls::DoggieStyle]

[Snow Trooper]