valve noise??

[thrift23]

I've noticed lately that under hard acceleration there's some noise coming from the engine. It sounds like valves ticking, maybe the timing in the tune has something messed up? What should I do? I've thought about putting the stock computer back in to see if I get the same noise. I guess that would be the best idea. Any suggestions?

[budhayes3]

What are your mods? The noise could be a number of things...my first guess (without hearing it) would be detonation. Other possible causes could be an exhaust leak, lifter, etc.

[thrift23]

I have a pcmforless tune, dual flo-pro exhaust, and a volant intake.

[BLK_TX_VHO]

I get knocking sometimes when I use cheap low octane gas (Kroger). I generally run premium to avoid this but if you use a good brand, 87 is fine. I experienced severe detonation with Hypertech's 93 octane tune. I moved back to the 87 octane tune and all knock was gone.

 

My mods include K&N 77, dual in/dual out flowmaster and Hypertech tuning. I do not want to do anything radical to the truck, thus the mods I've chosen.

[BenKey]

Gas octane/type would be the first place I looked.

 

Oil level may need a glance. If these trucks get as little as a half qt low, you will hear it.

 

Also, is the truck at operating temp when this happens, or does it happen before it is good and warmed up? In cold weather sometimes you will hear if the engine is not up in temp due to the oil being thick in cold weather, but usually goes away after its up in temp.

 

I wouldn't expect anything wrong with your tune just yet, but it would be good to log some running and see if you're getting any knock. I know you've already bought some good logging software, right?

[thrift23]

I've never used anything but 93 octane in my truck, even before the tune. I'm not sure if it was up to operating temp yet but I usually try to let it heat up before I really get on it hard. I will check the oil and make sure everything is good there.

[brutis1984]

My 06 SS makes a ticking noise during the last few hundred rpm's at WOT. I was told here that it is most likely knock retard. Basically the computer sensing knocking and retarding the timing thus reducing performance. I am told the sensitivity can be adjusted in tuning. Havent done that yet.

[BenKey]

My 06 SS makes a ticking noise during the last few hundred rpm's at WOT. I was told here that it is most likely knock retard.  Basically the computer sensing knocking and retarding the timing thus reducing performance. I am told the sensitivity can be adjusted in tuning. Havent done that yet.

<{POST_SNAPBACK}>

You cannot "hear" what the PCM is doing - like knock retard. It is a function of the PCM - it doesn't make noise. KR can occur once it senses certain things. Valve tick does not actually sound too much like knock, althoug it can cause KR if the knock sensors can detect it. Knock, or pre-detonation, has a much different sound.

 

The only way to know if you are experiencing KR is to log some runs. Many people on here need that capability, but refuse to get it.

[brutis1984]

My 06 SS makes a ticking noise during the last few hundred rpm's at WOT. I was told here that it is most likely knock retard.  Basically the computer sensing knocking and retarding the timing thus reducing performance. I am told the sensitivity can be adjusted in tuning. Havent done that yet.

<{POST_SNAPBACK}>

You cannot "hear" what the PCM is doing - like knock retard. It is a function of the PCM - it doesn't make noise. KR can occur once it senses certain things. Valve tick does not actually sound too much like knock, althoug it can cause KR if the knock sensors can detect it. Knock, or pre-detonation, has a much different sound.

 

The only way to know if you are experiencing KR is to log some runs. Many people on here need that capability, but refuse to get it.

<{POST_SNAPBACK}>

 

Software is on my long list of things to purchase. I personally am not hearing the PCM, this noise comes from the top of the motor. I can only hear it between first and second gear with the window down. As stated it sound like a fast ticking and mine is only at max rpm's. Ive tried different fuels and it is still evident. I have not tried racing fuel yet. What is your opinion of this noise we are hearing?

[Megofast]

With 95% accuracy, You have detontation. BE CAREFUL. It will damage the engine! The PCM doesn't create noise. It reacts to the frequency detonation causes via the knock sensor. The PCM "pulls"/moves timing to minimize or eliminate the detonation. Early turbo'd GM cars could pull 12-14 degrees of timing and now I'm unsure. Zippy and others probably know the exact number.

 

I would suggest having a new tune with a less aggressive spark advance. Back in the primitive days of tuning(OBD1) hypertech was known for disabling knock control resulting in a blown engine. Their products with most in the industry have gotten better.

 

Keep in mind, Atmospheric conditions (Altitude, baro pressure, humidity, temp) have an effect on the ability of the engine to run with differing amounts of knock/detonation resistance.

[BenKey]

You can adjust the max KR in the PCM with FS.

[Megofast]

You can adjust the max KR in the PCM with FS.

<{POST_SNAPBACK}>

 

thanks, I've been studying mode6. I gotta get back into performance.