2nd try: Diablo, what is the KNK FUEL RETARD PID mean?

[spencer60]

Going to try this again.... last thread and emails have gotten no response from Diablo on this.

Car is a 2009 Challenger 5.7 6-speed. I've been logging all the KNK sensors for a while now, and see KNK FUEL RETARD come up fairly often. It seems to be related to ST RETARD in that if it kicks in ST RETARD follows it. However ST RETARD kicking in doesn't always set off FUEL RETARD, so they are definitly different.

NOTE: this isn't "knk ST retard" or "knk LT retard", it's "knk FUEL retard".

Any help on this would be appreciated. I've searched every site I can find but there is almost no information on this sensor, and even where it's mentioned it's not explained.

[need-a-cage]

To combat knock, it should add fuel not take any out. Is this the rev limiter kicking in? I am not sure how it works on the hemi's, but my Mustang's stock rev limiter would cut fuel. That seems like a stretch though.

[johan]

In all the docs i have, the only definition i have for that is knock fuel compensation, which i would guess would be fuel added due to knock, which from experience must not be much fuel added as i have not seen an obvious condition of this as knock occurs.

[spencer60]

Johan, thanks for the reply. The odd thing about this PID is that if KNK FUEL RETARD goes up, KNK ST RETARD (which I understand is the total amount of Short Term Retard) always goes up as well. However KNK ST RETARD going up doesn't seem to have any connection with the KNK FUEL RETARD going up. That is FUEL will drive ST, but ST doesn't have any effect on FUEL.

I guess it's possible that in some cases knock is addressed by both retarding the timing and adding fuel (KNK FUEL), where the 'normal' (KNK ST) strategy is to simply retard the timing.

Again, thanks for the info. If you run across anything else on this PID, please post it.