I've replaced the entire ignition system... plugs, wires, ignition module, coil, etc... stuff that was getting tired anyways. So why not upgrade.

I'm still getting Knock Retard.

A/F is perfect with 128 BLMs and .925 at full throttle on the O2s.

Now, the exhaust may be questionable... the headers are tight and the Off Road Pipe (I've heard that could do it) is tight. But the Cat-Back is stock. After I installed the ORP, the muffler vibrated loudly... especially at idle for about 3 days. It doesn't make noise now. I'm wondering if the baffle broke loose and is rattling inside at full throttle.

I could just take off the muffler and run to see if I get a ticket... I mean... Knock.

Also, I do have Manley Chromoly Pushrods. I did the rocker lash about 5 years ago during the install Could they be needing adjustment?... A/F Mixture is good.

I do have the LT4 KM.

 

As far as your knock goes, if those are your readings, and you use 93 octane, it's probably fals knock. Just in case, test it by adding a little 94 -100 octane unleaded just to be sure. If it still reads knock, it almost surely FALSE knock.

 

Eventhough these are hydraulic lifters... I have not touched the rocker arms in about 3-5 years. This is the first time I've seen knock on Free Scan.

Could Rocker Arms cause Knock?

 

just a week or so ago one of my RRs can loose and was clacking pretty loud... my scanmaster was showing 2 degrees retard at idle so YES loose rockers will cause it but you should know if you have a loose rocker.

what i have done to solve a knock issue i had was to run my tank down to maybe a little under 1/2 gallon or so and add a gallon of toulene to my tank which is supposed to give you a few octane points. the less gas you have in your tank.. the higher your octane will be. i didnt really notice all the much of a reduction in knock retard(meaning its false knock) so i did some adjusting to the PCM tables so it wont pull out the max 10 degrees at WOT.

 

Thanks!!! I've been doing some research on line... it also said a gummed PCV can cause a misfire. Not very tough but I'll check it out this weekend. Also, I'll adjust the valves... engine off. I did it many years ago with the engine on but perhaps it isn't that accurate.

Anyways, do you have a link which will help me adjust my valves with the engine off? How many hours will this take?

 

This covers several ways of adjusting the valves. Doing it with the engine running is pretty accurate if you pay attention to what you are doing.

 

Thanks again...

 

I've always thought it was very easy to set valve lash with a good vacuum gauge. Hook up the vac. gauge to manifold vacuum, downside of the throttle plate(s), and start the engine. Back off one rocker at a time until the gauge starts bouncing and then tighten until a very steady vacuum reading is found. Repeat with each rocker. You might have to do each rocker twice to get the best vacuum reading. Worst part of this is the cleanup afterwards since the oil is squirting all over from the valvetrain. You can always pick up a set of clips for cheap to deflect the oil and cut back on the cleanup time afterwards.

 

Interesting idea... what if one is bad already and causing the vacuum gauge to flutter? In other words, I'm adjust number 1 while number 6 intake is off. Would that flutter widen while I adjust number 1?

 

In your example, you will have more "flutter" with #6 intake needing adjustment. As you back off #1, it will fluctuate even more, but should even out as you adjust #1. Once you adjust #6 intake, you should be get more steady vac. readings.