IGN ADV Side Effect

[blinding-gts]

I am running into something really weird with my car. I decided today to tune the IGN part of my map and when I advanced the IGN value in each cell by 3 I was getting a "crackling" noise coming from under the hood when I gave the car some gas from a cruising speed. The noise is exactly the same sound you hear when you slowly engage the clutch in from a stop (like the engine lugging) but for some reason it kept doing it when I was in gear (2nd,3rd,4th) and driving along. I'm not showing any knock increase on my logs..I was wondering if anyone knows what this is or has any experience with this?

[Jesse IL]

Not all knock gets picked up by the sensor, but that's definitely knock. That's why I say your ear is just as important a knock meter as anything else.

[blinding-gts]

That's some crazy sound for knock. :AF: I've heard knock before (friend's car) that sounded like someone had dropped marbles in the engine but never a subtle rattle like it did today. It literally sounded like the clutch plate not engaging fully from the diaphragm spring's pressure. The knock sensor doesn't pick that up at all. Good to know this though, thanks Jesse.

[jlitman]

A bit off topic, but I could swear I heard a sound a sort of like tossing a pebble into water or that obnoxious noise people make popping their cheek -- was that my engine pinging? :wtf:

[blinding-gts]

^^What you described sounds like mild backfire from the exhaust.

[jlitman]

^^What you described sounds like mild backfire from the exhaust.

Really? :confused: It was a very high tone, but not quite what I would have expected for a "ping" (more of a "boop" sound :laugh: ). That would be quite a relief if it was just a little backfire.

[enjoi4586]

Yea, the engine sounds somewhat more "raspier". What I always did if I wasn't getting a knock reading in the logs, but I could physically hear it, I would back retard the VVT and leave the IGN alone, and you should be cool. But thats jus a suggestion