knocking at wot

[sytygmc]

had recent tune up and changed cap and wires, still have knocking at wot. if i adjust wastegate for less boost, could that help problem?

 

[TyMeUp]

Check the basics first. For detonation only at WOT, I would check:

1. Base timing set to specs
2. ESC (knock sensor) operation
3. Fuel pressure and volume
4. Fuel quality

I would check #4 first if you fuel up at only one gas station. Try a different brand of gasoline. Also, did your tune-up include replacing the fuel filter? A lean condition at WOT will cause your problem (restricted filter, bad pressure regulator, or fuel pump on its way out should be considered).

Here's a more complete list:

http://www.federal-mogul.com/cda/content/front/0,2194,2442_7359_7525,00.html

 

[Falco]

Re: knocking at wot

had recent tune up and changed cap and wires, still have knocking at wot. if i adjust wastegate for less boost, could that help problem?

How do you know it's knocking? Do you use a scantool or just hear it? If you don't have a scantool get one hook it up and test the truck. Knocking can be caused by a bunch of things, however in our case most likely it's ignition or fuel. But could be more serious too...

Ignition wise you mentiond the replacement of the cap (I guess rotor too), wires. What about the plugs? What kinda plugs you have, how old, what gap?

As far as boost, how much boost do you see? Is your truck stock? What kinda mods, especially what kinda chip if any?

Answers these questions and we will see...

Later,

 

[sytygmc]

i can hear the knocking at open throttle and makes the ty bog forcing me to let up. friend used scan tool a year ago and ty was running at stock boost, around 14-15. i'm using stock chip. no major mods, just open filter, borla cat back. i changed cap and rotors, wires and used stock plugs. ty is running better after tune up but there is still some knock at wot.

 

[Sy769]

If you can hear knock you better do some work and get it on Datamaster.

Audible knocking means the ECM cannot pull out enough boost or timing to make it stop.

Continue with the knock=broken piston,bent rods,unhappy SyTyer.

 

[InvisiBill]

http://www.syty.org/old/promguide.html

Like Patrick said, the stock chip will pull out up to 12.7 (I think) degrees of timing to combat knock. If you can hear knock, you're getting more than the ECM can compensate for, which is REALLY bad. Get that truck on a scantool ASAP.

 

[Falco]

i can hear the knocking at open throttle and makes the ty bog forcing me to let up. friend used scan tool a year ago and ty was running at stock boost, around 14-15. i'm using stock chip. no major mods, just open filter, borla cat back. i changed cap and rotors, wires and used stock plugs. ty is running better after tune up but there is still some knock at wot.

Forgett the throttle for a while and get a DM hooked up ASAP. As I've mentioned it still can be caused by a bunch of things. Do you get error codes as well (check engine comes up)?
You fueling system could be out of pair, bad fuel pump, injectors, regulator, dirty filter (when was the last time you changed it?), etc... DM will give you an indication wheter it's lean at WOT or not. If it's lean you will have to find the weak spot in your fuel system.

Overboost could be an other reason for knocking. You have a non stock exhaust...

Find someone with DM and post the results here...

BTW, could you post what do use as stock plugs?

Later,

 

[sytygmc]

i used spark plugs CR42TS ac delco. also conrad cap and rotor from autozone.

 

[Falco]

i used spark plugs CR42TS ac delco. also conrad cap and rotor from autozone.

You are on the right track here. Hook up that DM and post when you have the file...

Later,