Detonation on 2014 5.3 with 18k miles

WendysOrBust · February 12, 2015

If you think this is an issue I would definitely find a way to log this. I know the handheld Diablo tuners can log detention/knock as well as EFI Live/AutoCal. Then take this information to the dealer and see if there is anything wrong. Most likely however is that the engine is running fine, other wise a check engine light would of already warned you about any issues.

TJay74 · February 13, 2015

I would have to look thru the codes, but I don't think the ECM trips a code or light for detonation, only for misfire events (Flashing SES light).

The way the ECM is setup there are 2 timing maps, one is the high octane map and the other is the low octane map. If the ECM records too many events of detonation (KR) with in a set time it will drop into the low octane map for a set duration until the last logged event decays out. Then it will come back up into the high octane map.

gone_fishing · February 13, 2015

I would have to look thru the codes, but I don't think the ECM trips a code or light for detonation, only for misfire events (Flashing SES light).

The way the ECM is setup there are 2 timing maps, one is the high octane map and the other is the low octane map. If the ECM records too many events of detonation (KR) with in a set time it will drop into the low octane map for a set duration until the last logged event decays out. Then it will come back up into the high octane map.

Interesting. Is this high octane map just for gasoline or is it also used when E85 is detected?

TJay74 · February 14, 2015

There are actually 3 sets of maps. Hi/Lo for regular timing, DOD Hi/Lo and I believe E85 Hi/Lo. Function works the same in all of them as far as knock retard (KR) events and transitioning back and forth between the maps.

Bassinz71 · February 14, 2015

Thank you for the relies everyone! As far as I know the truck doesn't have a tune on it and never did, Im not 100% on this but I can have the dealer check when I bring it back in. I filled the tank with 93 octane and 90 octane and did not notice any detonation or knocking. I did notice it had a rough idle after running on the highway and then idling in the parking lot for a few minutes, though. Im not sure if this is something new or I am just paying more attention to it know. Hopefully its as simple as a faulty knock sensor.