i recently put some GSC S1 cams in my JDM 8MR. before the day i also replaced my copper 8 range plugs. the cams are supposed to work with stock springs retainers so i didnt get the mechanic to change the stock ones.

ok how i have fairly large knock happening when i try and put the foot down from 90-120load areas in most rpm. saying that if i slowly take it to the load then it usually is fine. i tune my own car and have tried decreasing ign to silly levels but it hasnt helped. i even chucked a full tank of E85 and yep the knock is still there when i put the foot down.

i asked GSC and they think maybe a couple of the springs are weak and hence causing chatter. the question is if it is then i should change the springs ASAP cuz otherwise i might cause miss timing of the valves and damage to the motor???

the other thing pointed out was that the S1 can at times cause phantom knock, seeing there are a few good tuners here i wanted to ask if that was the case and if doing the springs and retainers would fix/make it better the knock issue. or do i need to find me my det cans.

thanks for any help.

 

I've always had a knock problem around 100 load at 2500-3250 rpm. I've gone crazy and pulled so much timing and had it so rich arond that area. Nothing helped. I finally chucked it up to phantom knock, because there was NO way it was real with those engine parameters at the time of knock. I did not verify it with a pair of det cans, so you should definitally try that! I've heard all kinds of stuff, from drive train harmonics to clutch chatter can cause it, who knows, its just a microphone that listens for a specific frequency at a time in the crank cycle. It could just be noise. Just make sure! Dont wreck your engine

 

What are "silly" levels? There were places where I had to pull 5-7 degrees in that load range.

d

 

If you are on good fuel and still have the knock it is a mechanical issue and not tune related. I would think possibly a lifter problem, valvespring starting to go away (maybe, havent seen it personally), a balance shaft delete can do it, etc. There are some reasons for it. I would try tracking it down to be sure but I would cut the knock control to above 120 load or so. It doesnt really matter whats going on that low anyhow.

 

I think I had pulled as much as 12 to 15 degrees. Said nope, this is not going to fix it. And flashed back the old correct map. Didn't change anything knock related. I think I lowered (or raised) the Knock Multiplier - Low RPM and I stopped picking it up. Sorry I cant be exact with my information, that tune was over a year ago and now im on V7.

What is the Knock Sum that you are seeing? 3 or 4? or like 20+

 

Small counts: 2-6. Never above 10. It was enough to screw up spool though. In my case the situation is little complex because I'm running very uncommon cam gear settings (+1, -3) and a fairly rare camshaft (helix 272s).

There's a lot of timing pulled in my v7 map (in the 2000-3500 RPM / 60-110 load range), compared to my OE 2004 Evo VIII map. It feels great though, so it's not at the top of my "fix-it" list.

d

 

by silly levels i mean load 100 and rpm of 2000-4000 went from 17 (starting) to less than 10deg of timing. no effect... thats running e85 mind you

 

Applaud's response to this question in the v7 problem thread.

https://www.evolutionm.net/forums/7806758-post66.html

d

 

I have heard of some people having this. Dont know if it was a mechanical problem or a tuner problem, but here a post to check out.

https://www.evolutionm.net/forums/5928610-post394.html

 

 

Knock counts occur when the noise is above the knock threshold. I don't see how logging knock voltage can help in determining real from false knock. Both false knock and real knock will spike above the threshold.

I think from what ziad has stated, my bet would be false knock, probably stemming from something mechanically related from the cam install. As long as a lifter or spring isn't damaged, I would think tuning the knock tables would be in order to relieve the issue.

 

The knock voltage shows the "noise". You can see huge spilkes in voltage when real knock results. False knock will barely cross the threshold.

 

No, that's not necessarily true. The amount over and the amount of time over the threshold is what produces the number of knock counts. John Banks explained the whole knock routine when he disassembled it.

And actually, the highest knock counts I have seen have been from false knock, where the knock counts get pegged at 36. So, there is no way to tell false knock from real knock simply by looking at the noise and threshold curves.

 

I had this problem and it was registering 36 counts and I was like there is no way, lowered the knock threshold and its buttery now...

 

lol this is funny. i increased the ign timing and the knock is lot less.... well ok it was only one run and it was clean till 200 load where i got a 2... but fuel dropped to mid 11s so maybe that was the reason as i hear that e85 needs obvove 12 for a clean run.