Just wondering if anybody else has troubles with Kr at low rpm, light loads as well or if it's just me. Mostly, it's between 30 and 60 load, and let's say from idle to about 2700 rpm.. it varies, but that's the general area. I've also noticed that in my particular car, the main culprit is cylinder 2. Since I have all of my timing tables the same, is this what's causing the issue? I know the Gm stock tune file has different timing for all 4 cylinders, which is kinda odd but maybe there's a reason for this. This is something I'd like to figure out n find a solution for, if anybody knows anything on the subject. Lately, I've noticed the car actually knocks a bit from an idle.. maybe it's not engine related, but I'm pretty sure it is; generally, there's no knock at higher loads and rpms.. might get a cell here n there but she's dialed up quite a bit at WoT. Car is still running fine and no loss of power.. could be fuel trims, but it doesn't really make sense to me in this case. If I rev it a bit in neutral, it usually gives about 2º of Kr and Only on Cylinder 2.. something mechanical maybe? Or a bad mount? Idk.. kinda confused. I tried reducing timing by quite a bit, and it did virtually nothing; in fact, I think it was worse.
Any ideas anyone? LoL

 

I see 3-5º of Kr on the stock tune on tip in. Are you seeing it constant at low load?

 

It's usually between 2º and 5º with the vast majority on cylinder 2.. just revving it to 1500 or so from an idle causes between 2º-3.5º on only cylinder 2.. no others are affected, but under light loads, 3 will usually follow suit and sometimes others will as well but at a much lower level.

How would I upload a short log to show you what I'm talking about?

 

Could toss a screen shot in HPT up. I'm not real familiar with it or tuning though, just tossing ideas around.

 

Maybe it's fine Idk.. but it annoys the hell out of me if it is... As a tuner, I should be capable of tuning such things out. A screeny wouldn't show much.. could see the wavy lines lol
I just did a ton of timing revisions on all 8 tables.. Gonna cross my fingers; if it doesn't work, I guess cam timing tables would be the next culprit. Hate to mess with such a good running tune, but I'm a bit of a perfectionist so to speak LoL

 

First off, let me just correct you in saying that the 4 individual timing tables are not set up for a corresponding specific cylinder. Each ignition timing table (just like the optimum spark table) is setup for varying loads, rpm and throttle position which translates more specifically into different cam positions for a given condition. The ecm then interpolates timing between the 4 necessary ignition tables for a given condition/cam position to allow further control of spark advance for varying conditions instead of just one 3 dimensional table for all conditions. It can be a tad confusing, but either way, it's not individual cylinder ignition control.

As far as your kr issues it's tough to say exactly if it's really "normal" kr without seeing a log. I hate to generalize knock as normal BUT, I guess I kind of will. Generally speaking, the lnf is prone to report false knock in low to medium load areas at lower rpms. It's been pretty well documented actually by quite a few tuners. I would probably say for you to see 1-2* pop up here and there is pretty relatively common just mildly cruisng, but 3-5* seems a tad excessive imo. I'd be curious to check out a log just to see what's going on there though.

 

What's your email? I just did a log after the updates I did... helped a little, but my timing is about 5º lower in the midrange so it'll affect my fuel economy and responsiveness; that being said, tons of torque at part throttle.. and that damn cylinder 2 is still acting up. Starting to wonder if I have an injector seal on the way out... I hear a faint knocking at light loads as well but it doesn't really sound like detonation if you know what I mean.

 

When the seal goes, it'll pop like popcorn at the slightest boost.

Splash in some E85 and see if the knock disappears. 4 gals/tank ought to kill it. If it leaves, it's real, if not, false. Check the downpipe/intake for rubbing. The slightest point of contact will show up as KR on the LNF.

25% E will shift your fuel trims ~8-10% positive but no worries for a test.

 

Unfortunately, we don't have E up here at all.. Maybe in Ontario but I'm not travelling 3500 miles for E LoL
Also, 09CSS1, I sent you my files on September 1st, did you take a look? Haven't heard from you lol.. in your junk email maybe? And also, I'd rather you not share my tune file at this point; it's completely my own creation, except the 2 or 3 things I mentioned, and isn't completely finished yet; always a work in progress

I also have a funny noise I've recently noticed and made a video of it yesterday.. sounds kind of fluttery and/or rattly, yet it doesn't show on the log when it does it. Any ideas? Always at low rpms; I have no knock at WoT either, except the occasional cell here n there.. had 1 cell yesterday at around 4200rpm but all others were 0
I gotta get to work now, but when I get a chance, I'll try n post up the video of the sound so you guys can hear what I'm talking about; this is other than the actual knock that I DO see in my logs.

 

I might try that...

I went WOT on the on ramp yesterday and say 3.9 degrees of knock which it jumped to immediatly. It sounds like false knock to me, but I am wary at WOT.

I know for a fact my Injen Upper CP is knocking against my frame so I wonder if that is what is causing the knock.

 

Try padding it some if you can't move it away. The knock sensors on the lnf are hellishly sensitive.

 

From what I'm seeing in the log, the kr does look like it's false just due to the rpm, load, tp % and commanded timing going on. I will say this though, your car seems to handle a freakish amount of timing for only running 93 octane (commanding 19* by 6500rpm).... unless of course you're running meth and I didn't know.

Also, are you running the stock valve springs? If so, you may really want to seriously consider lowering your limiters down from the 7500rpm where they are now to no more than 6800. Even if you don't "plan on" revving that high, there's still no reason to have it set that high with the stock valve train. If you accidentally miss a shift for some reason or spin the tires loose like crazy, holy valve float city.

 

Upgraded head from ZZP with stage 1 cams and yes valve springs.. I've set it up this way for the future; ZFR which may be installed this week if I get time. Sorry I didn't get back sooner.. been busy with all the **** going on in my life lol The fuel I use is 94 octane and it has roughly 10% ethanol in it; I discovered that using colder plugs with my setup allowed more timing and am running 2 steps colder now.

 

I've also recently (past month or so) noticed that there's a kind of fluttery knock if I blip the throttle and/or at light loads low rpm accelerating and generally only in the lower gears; could be cause I can't hear it at higher speeds as well, but ya. Anyways, my culprits are either the turbo wheel is getting loose and/or the downpipe connection to the manifold has a minor leak. Which is also why I may just tear it down and finally throw the Zfr on there as well. End of the season anyways, so I should be able to get an upgraded clutch over the winter before spring so it's not a bad idea I figure. Black Friday sales should be coming up soon so maybe I'll get lucky lol
I have a video I can try adding so you can get an idea as well; or maybe email you again. I still haven't had a chance to look underneath and was going to do it today but I have alot of other personal issues I'm dealing with as well so I may not get time yet again..

 

1. Make sure your fuel trims are dialed in. Make sure you have no boost leaks/exhaust leaks and that your 02 sensors are working fine.
2. LNFS KR at low load all the time. It's normal. The knock sensors can be thrown off by chain rattle, knock, or any other sort of rubbing. They are over sensitive.
3. KR at WOT in midrange/top end will almost always be real IMO. Assuming it's false is a big mistake. Reduce timing until it goes away. Boost is not always the culprit. I think up to 26 psi is safe on the stock motor usually (except for road course then it's 20psi). 26 psi on a bigger turbo even more safe.
4. I have had no success with any other plugs other than stock. I would use .32 gap for stock turbo. .28 for ZFR and .25 for anything bigger.
5. If all the previous 4 are taken care of, stop worrying. Drive the **** out of it. I do and my motor is still alive. Cheers.

 

Fuel trims are reasonably close, but it's impossible to get those perfect as well.. that's one thing Vince was good at though cuz he had them all at -2 somehow.. mine are up and down and it doesn't matter what I do, they're never perfect.
Kr at WoT in midrange/top end is almost nil and usually is. Occasionally, I'll get 1 cell show up around 4400 rpm I think it is, roughly, which is also where the turbo makes it's peak boost and it's also usually only on 1 cylinder that it shows up iirc. Not changing 1 cell on an entirely smoothed out table that flows the way it should; just doesn't make sense there, but I don't worry about that anyways. It's always the low load low rpm crap that bothers me. As a tuner, if I was any good, I should be able to eliminate it entirely; or at least that's what I think. Does every reputable tuner out there have the same problem with false Kr at low load low rpm? I've also noted that it's quite often only after stopping at a stoplight and sit for a minute, then go, that it does it. I've had it so close to perfect on more than 1 occasion, but it always comes back at some point. Log will be perfect for a day, or half a day, and then boom; it rears it's ugly head again.

Maybe you're right, maybe I should forget it and give up on it but if I'm tuning multiple cars in my area and they all do the same thing, isn't it my tuning that's the problem? I've experimented alot with my own car and done things that most haven't. And I've learned alot from my own personal experiences from doing so. The last guys' car that I tuned supposedly paced a C63 AMG so I figure something must be right. I just don't want my knock issues to become something to worry about lol cuz if they do, it'll be like a disease and spread to every car I've ever tuned and that wouldn't be a pretty situation. I'm pretty sure it's just false knock down there too, but how can one be sure?

On a sidenote, I still haven't had time to investigate my "flutter knock" as I call it lol.. so once I get time to figure that out, I'll probably update this as well with my findings. As I said before, I've experimented alot with tuning my own car, so it really wouldn't surprise me if the turbo is on it's way out. I have a Zfr ready to bolt on anyway lol I've pushed it, possibly hurt it, but she's still running strong even so. Have had the boost up to 26psi at times, and even accidentally spiked 29 once or twice; Ecm is weird sometimes, I swear it's female! Lol It's generally set at around 24.5psi or 25 max currently and it pulls strong.

 

Run a knock histogram and log the car. Reduce the timing by what shows on the histograpm. Then if it stays it's false. Like I said, the knock sensors are over sensitive. There is a thread on hptuners about the knock sensors and their positionings which may help. Probably clutch rattle, timing chian, or anything loose causing it to false knock. Part throttle low load knock is usually false imo.

 

Ya.. I kinda figured that.. except for my flutter knock which I kinda wanna take a look at right now.. wish I had a lighter though to check for exhaust leaks

 

Have you ever logged a 100% stock lnf or even a gms1? Holy kr city all over the place. Point is, like raver said, the knock sensors are stupid sensitive especially at part throttle on these engines. A kr histo is an obvious must so I only assumed you already had that in your config setup.. lol

 

Definitely try adding some E or race gas to see if it's real. I have a Trifecta tune with very conservative timing (13.5* up top) and get some KR in 4th. I didn't want to pull even more timing out so I use 2 gallons of e85 and 14 gallons of 93 every tank (HHR has a 16 gallon tank) which is e19 and it has mitigated the KR I was getting. My AFR hasn't really changed and my trims are still acceptable.

 

Actually I've never logged a stock Lnf or even a GmStage 1 lol.. everybody is modded around here.. I guess the closest thing was a Superchips tune that I logged.. and a Trifecta, both mine and somebody else's. Both had mad Kr.
Update on the "flutter knock" Just did my ZFR install yesterday/this morning and during the install I found that the gasket between the turbo and the exhaust manifold was cracked and leaking. Kinda figured it was an exhaust leak, but I like to be sure before I go flogging the car lol. I'll hafta see if that affects some of the Kr that I've been recently seeing more and more of after I finish it off tomorrow. Got one of the old ZFR's from last year and figured since I had this issue that I needed to solve, may as well tear it down and throw it on.. season's over anyways... 1 more week left so if I blow the clutch or tranny, I'll have all winter to upgrade them What a pita the install was though.. the only thing that fit properly/easily was the turbo to the exhaust manifold, and the o2 housing to the turbo.. everything else, and I mean everything, was an absolute headache. Can't believe my K&N intake doesn't even fit... oh well, I'll be happy once it's running and destroying a lot of fast cars lol. Already beat a trifecta tuned Zfr with my tune and K04 so it should be pretty interesting to say the least.
And I've said this before, we in Canada, do not have E! Lol.. I wish.. but noooooo.. probably not good to run all year round in our crappy winters; I'm assuming that's why but I could be wrong. Race gas is something like $3.00/litre or about $12/gallon.. and that's not even 100 octane iirc. Canada sucks when it comes to fuels.. you guys get all the good ****.

And yes 09Css1, I have histo's for Kr on all 4 cylinders plus Total Kr lol.. I just thought it could virtually be all tuned out.. guess that isn't the case? Lol

 

this thread helped me out alot. im getting up to 2.6* on GMS1 but only in first gear to get moving and then it goes away through every gear. i will have to move my intake and see if its rubbing on anything.

 

Something else that can help with the low load KR is to adjust your injection timing. I've had great results in doing so.

FWIW

 

I would but im on GMS1 currently until i get a revision from Trifecta when i get around to it. last time i had my trifecta ECU in i got alot of knock, might have been false but i switched back right away

 

Trifecta.. Vince is great at making trims the same across the board, dunno how he does it, but his tunes aren't the best.. I've run both and worked my own Hp with better results than he gave me. Low Kr is apparently quite common but I've come up with a solution that seems to be solving it.. keeping my fingers crossed; I'm on my 5th revision of it now. It may never be perfect, but a little Kr from 800-1800 from a normal start from 0 isn't going to hurt anything.. I just hate seeing it in my tune logs LoL