Help guys, I am going crazy chasing this problem down. All that comes up in search is people turning the knock sensitivity down, or off all together, not something I want to have my tuner do.


It all started out of nowhere. The symptoms are:


False knock (atleast I think) At partial throttle (say 50% to even 70% some times) at full boost all the way till red line, it pulls no timing, and runs really great, no detonation.

It will only do it at full throttle, when I stab it hard. If I hold partial throttle all the way till near shift point and ease it into 100% its fine. I think its false, Plugs look fine, and my afr is totally fine right on the money. I have ZERO oil in my intake pipes, have new knock sensors, patriot valve springs, and have a rock solid tune from a very reputable tuner. There is no audible noise. I only check and trouble shoot at night too, to be extra safe, when it is 40 degrees out.


I am now thinking that it may be my harmonic balancer.


What do you guys think? Sensor related? Am I over looking anything? I am positive it is false knock. Guys I really need some advice. Thanks in advance.

 

Did you log it to see if it is burst knock?

 

Need more information. What does the full setup consist of? What is your WOT A/F ratio, boost level, timing, etc? Have any logs to post?

 

I had false knock when I pulled away, it was the darn exhaust banging, it retarded my timing, was chasing that for sometime until i found what it was the headers.

 

Put some hi octane fuel in it, and see if it still knocks. That'll ID for sure, false knock.
Maybe, a description of the setup would provide some insights as to other potential problem areas....

 

I have no data logs, I dont have the equipment to perform them. The most I can do I use my interceptors, maybe use my friends tech 2.


My mods consist of the following:


STS rear mount, under axle piping, texas FMIC, 42 lb/hr injectors, patriot gold valve springs. Stock manifolds wrapped all the way back to turbo, t67, racetronix fuel pump with hotwire setup.


My afr sit right around 11.3 or so, and do not change much. I have been down the banging exhaust road before, when I had SLP subframes, and my y pipe hit them, causing false knock. I have checked everything under the car, intake and exhaust, no noise of any sort down there....



What is burst knock? I am going to try looking that up right now. Also, I checked my coils, two of them seem to be going bad, there is some "crap" on two of the coils plug ends... How ever, I am getting no miss fire codes, no codes at all. Could spark be "blowing out" in two cylinders causing this?

 

You will get burst knock in FI cars fro rapid changes in airflow or a choppy VE/MAF configuration. It needs to be desensitized or disabled. It sounds possible considering you said it doesn't happen when you lean into the throttle.

 

It only happens at full throttle, and above 3500 rpm. Its strange, at full boost below that rpm range it won't throw knock. But if I "ease" into full throttle, it won't do it, and pulls like a monster. I just don't what gives, especially when it isn't going lean at all according to my wideband....

Plugs look fine too. Even on the dyno when my tuner was doing his thing, he made pulls with as little at 13* timing..... and it still did it. At first, I thought it was oil in my intake system. But now that is cleared up, it still does it. Sometimes it won't do it at all, I can make 3 ggear pulls and it will not do it. That's why I am thinking my harmonic balancer is off or something along those lines. What should I check next?

 

Ok guys, last night i took the car out to check it out some more, and it seems that i can prevent it from showing knock by simply slowly going full throttle, if i am to floor it quickly, it will show knock.

Would an issue with my catch can cause something like this?

 

Really need a log of it occurring or post up the tune file. Everything else is a guess.