Knocking/Pinging confirmed; NOT flutter

[jimveta]

I've been having light pinging noises. Very little when it was stock, a bit more after I had my custom exhaust, and definitely more after my supercharger. I always thought it was this "flutter" problem people have been talking about, until I heard the flutter recording made by summitx which I have posted at http://www.idrive.com/jimveta under Storage, Shared, superduty-flutter (links available on first page; right click and use "Save As")

My pre or post ignition (dunno which one) knocks absolutely do not sound like that flutter.. I think maybe others have the same noises I have, who suspect pinging/knocking as well.

Well, I finally have confirmation that it actually does detonate (pre or post, again, dunno). However, the pinging is not that loud or drastic because, by the knock sensor, the computer pulls timing ALL the way back in my case (which is really bad for power) -- and this was how my pinging was confirmed. The shop that's doing all the mods plugged in the machine for measuring the ignition timing and found that definite indication spark retardation (if I understand correctly, once it senses the knock, it'll keep on retarding until it feels it safe to ignite by measuring voltage across the plug tip, through the vapor, or something like that? before sparking)

In fact, it must have been somewhat bad on mine even though the sound was every so slight because it pulled the timing all the way back as much as it could and it still knocked just a tiny bit. I strongly suspected this after driving it with the supercharger but wasn't so sure before it. And actually, I'm so glad that it still pings after the retarding so that I can hear it and get it corrected, gaining that powe lossed. Now, they're going to reprogram the chip as well as replace the spark plugs and see what happens next (with stock throttle body then the aftermarket one I had bought a while back).

[This message has been edited by jimveta (edited 12-12-2000).]

[This message has been edited by jimveta (edited 12-12-2000).]

[jimveta]

Just wanted to add that the flutter really sounds similar to an exhaust leak, whereas pinging, at least in my case (after pulling back on the timing from the knock sensor), sounded like "cackling" under load -- not fluffy and blow-y (like you might be able to do with your lips) sounding, but sharp yet light (low volume), "ckkclk clk clkcckck.."

[summitx]

jimveta,

I should mention that I still do not know if the problem I have is the same as the exhaust flutter that F--D declared in the original SSM. Maybe what I've got is a detonation problem.

Flutter, is supposed to be only on CA emissions equiped vehicles and can be fixed by the new y pipe.

[jimveta]

hey summitx, thanks again for making those files. Well, I hope that it really isn't knocking for you because if it were, it sounds pretty serious. But Ricky (n2boost from vortech) said he had the same flutter problem and was positvely sure it's not detonation, plus if it reduces with the new y-pipe or better yet, if high octane gas or octane booster (NOS off-road or racing formula) really helps, it probably isn't.

Mine's also a CA, however I didn't know it applied to only us.. Maybe I'm lucky to not have flutter as it seems to drive people on the brink of insanity (or maybe not.. because if I ignored my problem, which seems easy to do as many people riding don't notice the pinging, I'd be slowly and quietly destroying my engine)



[This message has been edited by jimveta (edited 12-13-2000).]