Yelo

How in the hell do you get rid of part-throttle knock at low rpm, WOT and PE mode are fine, it's under light load at part throttle under 2500rpms that it'll knock like nobody's business. Picture going up a slight incline at 15% throttle and having the motor sound like it's got marbles in it....give it a little gas to accelerate and it goes away....all I know it that it's starting to **** me off !!

I'm going to guess it's a combination of the higher outside temps right now and the timing being a little too high for the charge temps....anyone else care to guess ??

PappyDan

iTrader: (4)

when was the last time you changed your fuel filter?
next time you fill up the truck get it from a diffrent location.
the way things are getting on gas prices i would not put it past any station
to put a 89 grade in to it's 93 grade tank to earn a few extra bucks.

12sec.5.3

iTrader: (1)

You need to make a log of that. See how much air the maf is taking in and multiply times 15 and divide by the number of rpm's in that same frame. That will give you grams/cyl. Then go into the octane tables and take out timing at that rpm and g/cyl cell and go try again.

Yelo

How the hell do you log knock ?? (NOT knock retard...knock...I'm not getting any logged knock retard...which is another issue)

dc_justin

iTrader: (13)

If your knock sensors were doing their job correctly, you wouldn't have audible knock. Have you de-sensitized your sensors?

Yelo

They're not de-sensitized any more (they were...but since I've been trying to fix this issue I've gone back to the stock settings...and it STILL audibly knocks)

dewmanshu

iTrader: (4)

so you have audible knock, stock sensor settings, and you get no pcm pulling? How positive are you that all the settings are correct. No codes of low voltage with knock sensors, p0327 and such? I'd at least make sure your knock sensor are working correctly, you did a complete motor tear down right? Possible bad hookup? I've never down it, but I beleive you can set some pid's to watch their voltage, to at least make sure they aren't flatlined.

Yelo

I double-checked all of the settings this morning...all stock. I reflashed the pcm with the EXACT SAME tune I read out of it and now it seems my knock-sensor issue is gone, along with my knock (which is being pulled by the now-functional knock sensors). I'm starting to think the '99 PCM's are alot more flaky than GM would like to admit !!

dewmanshu

iTrader: (4)

gonna have to agree with ya on that one.