hi all
since i have owned my 99 sti wagon the psi3 have shown a kc or knock correction of 0.0. I have taken car to local ecutek garage where they kindly plugged car in and it was reading 0.0 on the laptop there too,although the advance multiplyer was reading 8.
now question is: is this correct??
i am assuming that the psi3 would only read different is there was any knock correction taking place?
also am i correct in thinking the advance multiplyer should be at 16=good,8=neutral any lower=very bad???
so am i ok or do i need anything checking??
no error codes btw
cheers in advance
tim

 

anyone??

 

Hmm, something doesn't sound quite right there.

As you may have already figured out, there is more than one source of knock correction within your ECU; there is an immediate response (which pulls ignition timing immediately on detection of knock and then quickly reverts back to normal), a fine learned knock correction (a table which "learns" when particular parts of the map are prone to knock and slowly removes or adds ignition to those areas) and the ignition advance multiplier (which is really an octane estimator, and removes a shaped pattern from the ignition dependent on the octane you are using).

I don't know much about the PSI3, but my guess would be the reported knock correction is most likely the second of these values. The fact this sits at zero does not mean the other two are not pulling ignition.

But there sounds like a deeper problem here. Before anything else is done, the ECU "learns" the octane rating of the fuel by setting the ignition advance multiplier. On ECU reset, this is set to some nominal value (typically 8) and searches for the octane rating of your fuel by increasing or decreasing the value while looking for knock. During this search phase, no correction is applied in the fine learning map. If you are using good quality fuel, and everything is in order, the ignition advance multiplier should quickly rise to 16 after a reset with a number of power runs.

The fact that it is sitting at 8 does not sound right. It could be a number of different things.

One possibility is that the +12 volt memory backup connection line to the ECU has become disconnected somehow and the ECU is resetting every time you park it up. (This sometimes happens if people incorrectly wire a turbo timer into the memory backup line).

Another possibility is that the car has been remapped without due consideration to the learning parameters of the knock control.

Another possibility is that some fault with the car is preventing it from learning, although this seems unlikely as most faults like this would result in a CEL.

But the car will be underperforming if the IAM is stuck at 8. It might be worth logging the value while out on a blast to see if it changes when being driven hard.