Had the J/A off for about a month due to slow warrenty work (bubbled side mouldings and idler pulley). Asked for the reflash and they were clueless, got tired of not having my truck, so juiced it back up and drove it. Anyway, driving to the dealer for the second time as I got to 180 degrees (no juice) I developed a light knock at very light throttle pulling away from the lights. Got to dealer found two techs standing around talked one into going for a ride (they could not duplicate a knock last time), sure enough with the mechanic on board she would not do it! So went home and juiced her back up. Quiet UNTIL I reach 180 and now the knock! And I can duplicate it everyday. Very light throttle only, a little more and it goes away! Several tanks of fuel and always use primrose performance formula. Am I ok to just drive this thing?, and turn up the radio (maybe get a loader exhuast) or just stay heavy on the throttle LOL! Runs great, and no real problems for 13k miles.

sounds like that known injector knock on the LLY's with Edge without the update.. I also have gone to the dealer and been told I was crazy and there was no update. I called another GMC dealer and he looked it up just like the first one..he found it. Edited by: briano

This should help you out. Print a copy of it any give to your dealer.



<H1>04 6.6 LLY Smoke , Fuel Knock , Surging and High Injector Balance Rates - kw white black idle surge rough noise accelerate P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 miss misfire SES DTC #PIP3129 - (Sep 10, 2004)</H1>


04 6.6 LLY Smoke, Fuel Knock, Surging, and High Injector Balance Rates


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The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.<A name=ss1-1549221><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1549221&amp;psdid=437&amp;evc=sm#ss1-1549221" target="_blank">
<H5>Condition/Concern:</A></H5>


Customer concern may be a low speed surge (8 to 10 mph or near 1000 RPM), acceleration fuel knock noise at 1500 to 1800 RPM, rough idle, white smoke at idle, or high positive injector balance rates.<A name=ss2-1549221><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1549221&amp;psdid=437&amp;evc=sm#ss2-1549221" target="_blank">
<H5>Recommendation/Instructions:</A></H5>

<LI ="1">High positive injector balance rates (over +4.0 in park or +6.0 in drive) may be causing white smoke at idle or while driving.
<LI ="1">Document all injector cylinder balance rates at the beginning of the diagnosis.
<LI ="1">There is an updated calibration to address the white smoke, high positive balance rates, idle surge, and a fuel knock noise at or near 1500 to 1800 RPM.
<LI ="1">Install the updated calibration and evaluate the smoking, high injector balance rates, idle surge, and fuel knock noises.
<LI ="1">If there is still a mechanical concern with an injector, and balance rates are still over the SI specification of +4.0 in park or +6.0 in drive, replace only the effected injector. </LI>


NOTE: Before any injector replacements a large fuel sample should be taken from the fuel filter and checked for contaminants or poor quality.

and if the reflash doesnt do anything or makes it worse, bring it back in and tell them you checked it on a tech 2 and saw the balance rates out of whack, and let them check it out. One thing to remember is that when we add programs to the trucks, you will get more noise from them, there is no way around it IMO - but its not all bad unless its a very serious noise - JMHO