Chasing knock issue

[nastang87xx]

Hey guys, I'm chasing a knock issue with my car. Whenever I go close to WOT or at WOT I will get about 2 - 4* of positive knock no matter where I am at in the RPM band. I can put it to the wood at 3000RPM and I'll have knock all the way until redline. It could be at 6500, I'll have knock. The fuel I am using is 91 but with more than enough of Boostane/Octanium. I've also tried mixing 100 octane with that 91 and I get the same results. Now if I go PART throttle and take my car throughout the entire rev range I will have no knock or even timing added. So on one hand I'm thinking it's not false knock but on the other it potentially could be. Looking at my logs, total timing advance at WOT through the entire pull is about 19 - 21*. And again it doesn't matter where I start the pull in the rev range. WOT = timing pulled. Partial throttle = no knock/timing added. I'm really stumped on what to do. Mods are a Corsa X pipe, and a Ford Performance passenger side catch can.

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[nastang87xx]

Also, I can't seem to find anything rattling around that would create false knock but I'll listen to any ideas at this point.

 

[THX 138]

False knock, maybe? Do you still have the OEM rubber dampers on your exhaust? Those came loose on mine and caused a nasty rattle. Easy fix, if that's the case... Just put some Loc-Tite on them and screw them on tight again.

 

[honeybadger]

Sounds like it's related to exhaust to me. Do you have headers? Are they rubbing? When my oil pan was rubbing and I thought it was headers, I was getting a knock issue according to the data logs.

I'd check the entire exhaust setup really thoroughly looking anywhere it could be touching the frame.

 

[nastang87xx]

False knock, maybe? Do you still have the OEM rubber dampers on your exhaust? Those came loose on mine and caused a nasty rattle. Easy fix, if that's the case... Just put some Loc-Tite on them and screw them on tight again.

Yes I do. I'll check those out.

@honeybadger , no headers. Factory manifolds and cats. What was going on with your oil pan, now?

 

[honeybadger]

Yes I do. I'll check those out.

@honeybadger , no headers. Factory manifolds and cats. What was going on with your oil pan, now?

Back when I had the FP350S pan, it was rubbing on my steering rack and giving me a vibration on hard left turns.

 

[nastang87xx]

Back when I had the FP350S pan, it was rubbing on my steering rack and giving me a vibration on hard left turns.

Gotcha. Yeah I'm just doing straight line pulls. I haven't data logged on the road course.

 

[nastang87xx]

Flex pipe is rattling. Guessing that is the issue.


https://1drv.ms/v/s!AkyPRgh342VGjBsWhyogEK-YCT2d?e=HMXkfb

 

[Hack]

I bet that Voodoo makes great power at -20F, huh? Almost like having forced induction at that point.

Traction could be an issue, though.

 

[nastang87xx]

I bet that Voodoo makes great power at -20F, huh? Almost like having forced induction at that point.

Traction could be an issue, though.

Ah yes, so I'm actually not in Wisco anymore. Socal. I did take my car out once in like single digit degree weather because I had to play some musical cars in the garage. It was...touchy.

 

[Hack]

Ah yes, so I'm actually not in Wisco anymore. Socal. I did take my car out once in like single digit degree weather because I had to play some musical cars in the garage. It was...touchy.

I was thinking you probably weren't getting knock in our current outside temperatures.

 

[drummerboy]

Flex pipe is rattling. Guessing that is the issue.


https://1drv.ms/v/s!AkyPRgh342VGjBsWhyogEK-YCT2d?e=HMXkfb

is there anything you banged on that did NOT rattle it?

 

[nastang87xx]

is there anything you banged on that did NOT rattle it?

Yeah lol I wanted to make sure it was indeed the flex pipe. I'm going to replace it with solid pipe. A little more NVH,meh. More pwrz.

 

[Champale]

That is a very interesting video to me because I have been trying to track down a metallic clinking noise that only happens after the car has been driven for maybe 15 minutes and then driven over small, sharp bumps. Now I'm wondering if the mesh is the issue, although when I have jacked the car up after driving then pulled and yanked on the exhaust, it never made a noise. I didn't try smacking it like that, though.

 

[Vettel-ish]

Ah yes, so I'm actually not in Wisco anymore. Socal. I did take my car out once in like single digit degree weather because I had to play some musical cars in the garage. It was...touchy.

I was about to say..I bet its pissed your driving around in -15 and its telling you lol.

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