Is this knock?

[Def]

So I've been chasing this problem for a while and am out of ideas at this point.

Symptoms: Partial throttle "knocking" sound that occurs from ~2-3.5k RPM and about 1-4 psi ONLY.

Conditions: AFRs are about 12.0-12.5:1 in this area. Timing was originally about 30-32 degrees BTDC at about 0 psi and 3.5 RPM(can't remember exact values from datalog now). I took off 4 degrees of timing in that area and had NO change.

I took out my plugs and saw no signs of detonation(little aluminum specs on plugs), but did see "burning" around the insulator above the threaded/hex metal portion. They were NGK BKR7EIX plugs. I put in some Denso equivalents(IK22's? something like that - iridium still). Noise was maybe slightly less, but not a big change.


Now the only thing that makes me think it might NOT be detonation/knock is that given the rest of my tune everything in that area should be fine, and I'm not exactly a n00b at tuning. In addition, it's a bit slow for knocking from what I can remember of knock on other engines. It's almost like it's happening about 2-3 times a second, which isn't near fast enough for over 3k RPM.

I don't have a gasket from my downpipe to exhaust(extended exhaust to match up with DP with another muffler) - could this cause an almost "knocking" rattle noise from this exhaust leak? Exhaust leak isn't really noticeable at idle, so I never bothered to fix it since it does like to blow gasket out on the track.


Any ideas? :wtf:

[Def]

Anybody? msg length

[ka-titties]

you know, i have a similar problem. there should be no reason i'm having this problem. the rest of my tune is fine. it only happens on mid-throttle, but high load, like going up a hill or something.

[jspaeth]

You are SURE it's a knocking sound? Or is it a clicking sound?

I know this is retarded, and hopefully not insulting to you, but at low RPM on parital/full throttle, my AVC-R solenoid clicks pretty loud.

[Def]

It sounds similar to knock, but a bit "slower" than I'd think it'd happen for the RPM. I do have a GReddy Type S EBC, so maybe I am hearing the solenoid or something. I have a vented hood, and I guess I seemed to notice it more after I put that on since it doesn't seem to muffle anything. I might wrap up the solenoid and see if that's it.

I can't think of anything else that would cause the sound except maybe a weird exhaust leak, but I'd expect to also hear that at idle.

[ericb382]

does it happen only under load or in neutral/clutch in also?

[jspaeth]

A video would be helpful here

[jackal264]

and wtf kind of motor are we talking about?

s14 and s15 sr20's get the vvt knock between 1 and 4k rpm when the unit starts to give out.

[ka-titties]

mine is a ka-t. it only happens under load. 0-3,4 psi of positive boost pressure and 20-50% throttle. if i give it more it goes away.

[Def]

and wtf kind of motor are we talking about?

s14 and s15 sr20's get the vvt knock between 1 and 4k rpm when the unit starts to give out.

Redtop SR
stock internally, 264 HKS cams, GT2876R 0.64 A/R, FReddy intake mani, GReddy VSPL FMIC, usual exhaust bolt-ons.

I don't think a video will capture it, but I'll try to get something as soon as I get my new FLCAs and HICAS steering rack installed(might be a week or so).

[grnappletree14]

i have same problem mine just start clicking/knocking.... i think it all started cuz i was low on oil and i ran my engine and i think the lifters need to be readjusted.... my motor runs good still after i put oil in it.... just about 2-3.5 rpm its makes a clicking noise i dunno y....

[Def]

My oil is on the full line, and it never uses a drop of oil, so I know it has never been low.

[slider2828]

Personally to me, it sounds like piston slap.... Has it been rebuilt? SOme people say after SR Rebuilds there is piston slap because certain pistons shrink and expand under heat. Now JE on honda's have been know to do this, but I heard of a few that has done this as well. I would maybe check leak down and or compression.....

[Ceepo]

lifter noise? maybe your lifters need to be rebled?

[KasperSlide]

ive got the same prob 2500-3200rpm less than a 1/4 throttle. but wot or past 1/4 throttle i never hear it
noticed it after i put my cams in hks step 1 256. i was thinkn i have bad lifter?
or maybe ign timing issue?

[armand]

i also have the same exact problem. it does it at 2500-3500 rpm at 1/4 throttle, and if i am in neutral and push the clutch pedal in an that rpm i can feel a rattle in the clutch pedal.but may motor has been doing this for4 years ever since the motor was rebuilt a redtop sr20.could it be a lifter problem. they have been bled a couple of times and no change.

[kimch99]

I think the best way for anyone to diagnose it is just to hear it for themselves tbh.

However seems to me that it would be more of a block issue than in the head.

[ka-titties]

my ka was rebuilt. decked head and stock pistons/rods. idk, very strange. weird to see so many people with the same problem also.

[93nismo]

my ka does that after about 2700 or so but only through 3rd gear. i hear a faint ticking noise. but its only after 2700rpm and only in 1-3rd gear. stragne. im thinkin its lifters. i burn a little oil so i unno. maybe that my issue. car still runs fine now though. its been doing it to me for the past 3-4 months now. i dont ALWAYS hear it though

[Def]

Personally to me, it sounds like piston slap.... Has it been rebuilt? SOme people say after SR Rebuilds there is piston slap because certain pistons shrink and expand under heat. Now JE on honda's have been know to do this, but I heard of a few that has done this as well. I would maybe check leak down and or compression.....

Stock pistons(which looked fine when I changed the plugs). Never rebuilt.

I doubt it's the lifters, as the motor is extremely quiet with respect to valvetrain noise at idle or just driving around. This noise is also too loud to be just drivetrain noise picking up(I'd imagine), and it goes away above/below that RPM range and with more or less manifold pressure.

Oil pressure is good, in fact higher than most people say on here(it'll hit about 85-95 psi max, does about 20 psi per 1000 RPM +/- 3-5 psi. Maybe the oil pump was shimmed by the previous Japanese owner(motor was stock except some HKS Platinum plugs), but I've had this motor for almost 6 years now with no real issues to speak of. I've tuned it since about 5 years ago.

[steve shadows]

Anybody? msg length

sounds like Timing Chain or Rod Knock to me,

100% of the time those both start to fail you will first get knock at 3K rpms, then from 2K to 3K then as it gets worse from 2K to 4K until your motor fails.

If it's very loud and obvious I would check your Oil Pressure, your oil pump might need to go.

If you're sure it's Knock from the motor actually knocking in the combustion chamber it should sound much LESS SHARP of a sound, like sand being jingled inside of a coke can.

[Def]

Rod knock would be bad... but oil pressure has always been fine. I have a Defi Link oil pressure gauge, so the thing lets you know in a hurry when you drop below your oil pressure warning threshold(~10-12 psi for me).

Would you really hear the timing chain flopping around when you've got 60 psi of oil pressure on the tensioner? Every car with timing chain rattle/knock I've heard did it at idle/just off idle.

[sidedrifts13]

i got the same problem check out my video
YouTube - S7303323.AVI (http://www.youtube.com/watch?v=IXeZPbhfs8M)

[Def]

That sounds like rod knock to me. Mine is nothing like that, as my engine is quiet at idle. I only hear a little bit of a sound around 0-3 psi of boost and low-midrange RPMs.

[steve shadows]

Anybody? msg length

You really?

You do know the difference between "Knock" mechanical and "Knock" from detonation right?

They sounds completely different. If you're knocking from too much timing as you mentioned regarding your map then you will hear something that sounds like sand jingling around in a coke can. But you really shouldnt be "knocking" with NO LOAD at idle condition or out of gear and not loaded up on the motor.

If you're hearing a sharp tapping sound that is mechanical noise knock. If it's a sharper whisping sound then get a glove on that is just thin enough to feel if you blow on your hand and with the car COLD, after sitting for a while before the mani is super hot put your hand down by the manifold to head area and turbo and try to feel for some leaks.

Also if you have a PFC or other EMS that can log knock, log it and see if you're getting and readings

If you can send me your map to look at and pp my 40 bucks I will go over this with you on the phone and try to get to the bottom of it, if you're sure it's a detonation issue. I just need something for my time but I will give you as much as you need of mine if you can make a donation to my recces pieces fund

sorry if I repeated any remedies

[Ceepo]

I also have this problem, i think i have an exhaust leak(gasket failed from elbow to downpipe) but im not 100 percent sure, my motor is all brand new about 3-4k miles since rebuild i know its not a rod knock, only happens at about 2500-3000 rpms, same noise as OP described...

Sr20det Redtop(in s14)
Fresh Rebuild(new pistons, rings, honed, decked, valve seals, oil pump, bearings, ect)
Stock t-25
FMIC/Piping
HKS BOV(not recirculated)
Megan Elbow/Downpipe
BC spec2

[redline racer510]

check your valve train clearances. I doubt its rod knock or piston slap probably just something you overlooked.

[redline racer510]

piston slap sounds like a really mellow pop detonation is like a metalic pinging noise.

[Def]

Just thought I'd update this thread, as I'm 99.999% sure I've found what the "issue," is.

Compressor surge.

I have a 0.64 A/R GT2876R - I knew the compressor was on the verge of surging at lower massflow/pressure ratios, but it's not much of a concern so I never really calculated it out.

So it looks like the engine is just not flowing enough air in this 1-4 PSI range, and only in high gears does it obviously happen, since the turbo won't make 1-4 psi sustained and hold the RPM that low(it accelerates through it).

Like I said, it was not a really fast "ticking" sound, but it definitely didn't sound mechanical. It sounds VERY different from the surge you get when your BOV doesn't open at say 3-4 PSI(i.e. HKS SSQV), so I guess that's why I didn't immediately connect it with compressor surge. But sure enough, pretty sure it is.

Looking at compressor maps, I don't think GT2871R guys would experience this, and it's not even a big deal. I never took a video because I didn't think a camera could pick it up well. It's not as loud as the exhaust.