blk-majik

iTrader: (6)

I've been data logging on my X since I got it a few months ago, and I'm yet to modify it at all because I'm consistently getting a few counts of knock between 5750 and 6500 RPMs. Most of my logging is done in 3rd gear at WOT. However, I've also reproduced this in other gears. I received my car with the 56280020 factory ROM, and the only change I've made was the Mode23 modification to enable logging. The car has only ever been fueled with 93oct pump gas (10%-15% ethenol mix). I've also tried Gunzo's base ROM for a few weeks, which had the same knock issues.

I should note that my car seems to be in the high end of performing stock X's. On a Land&Sea dyno, I recorded 280whp/275wtq. We all thought it was high, so everything was triple-checked and run again... same result. DataLogLab dyno simulations show my car to put down about 265-270hp/260-265tq. I'm not sure if this makes a difference, it's worth mentioning.

Specifically, I'm usually recording one or two counts of knock just before 6k RPM, and recording 1 count until just before 6500 RPM, where the knocking stops. Sometimes I'll get 3 or 4 log entries with knock, sometimes just one.... but I ALWAYS get at least one. It's not severe, but it's also not normal, and that's my concern.

Some other parameters to consider: ARF is between 9.9 and 10.1 (via LC-1 wideband). Boost is dropping from 17psi to 14psi when the knock occurs. IAT is dropping, while Coolant Temp remains constant. All fuel trims are almost 0. Timing Advance goes from 18 to 22 during the knock window (which matches the ROM table).

So my first question: Are a few knock counts in this range normal on a stock X? I've searched and looked at a few logs from other people with no modifications, and getting any knock does not seem to be normal. Same goes with Gunzo's ROM. Others get no knock, I do. Am I right about this, or am I just being overly cautious?

Second question: If this is NOT normal, what could be the causes? Could having a slightly stronger-than-normal car account for this, or is it more likely due to something relating to the car sitting on a dealership lot for the better part of 2 years? I need to pull the plugs.

Third question: Should I just try to tune it out? I did a short test where I lowered the value of the cells being called in the High-Octane Time Map by 2-3 degrees and tapered the surrounding cells to smoothen the transition. It seemed to have little impact, and if nothing else, may have made it a bit worse. I figured that would fix it, which is why I'm posting

I'm still learning here, so any input is appreciated Thanks!

poof101

i dont mean to sound stupid...but can someone really explain to me what knock is, and does it really sound like a knock...dont flame me...and tell me what WOT is...ive tried searching but no lucl

blk-majik

iTrader: (6)

Knock: http://en.wikipedia.org/wiki/Engine_knocking and http://www.misterfixit.com/deton.htm
WOT: wide open throttle

nj1266

iTrader: (6)

1-2 counts of knock is nothing to worry about. Almost all of the stock Evo Xs that I have logged have 1-2 counts of knock in the range that you mentioned.

blk-majik

iTrader: (6)

There goes the premise of my first 2 questions I know its not a big deal, but as a learning exercise, I wanted to verify before moving forward. Whats the best method for eliminating it? I tried decreasing the timing advance a bit, and it looks like it made it worse. I'll do a few more sample runs just to be sure.

Nj, I've compared my changes to you're 91oct rom. You're running WAY less advance at high load regions. Maybe my baby steps are just too small I haven't tried your rom (since I never use 91oct), but comparing to Gunzo's rom, he didn't dial the timing back much. Then again, I'm still getting some knock counts with his rom

edit: I'll try lowering the advance BEFORE the knock cells, as well. Thinking back to why knock happens, the heat that would cause detonation would be caused before 6k RPM (probably when boost is higher), so reducing that should reduce the likelihood of detonation later one, right?

spdracerut

iTrader: (2)

The 91 oct map I made for my 2005 Evo had 6 degrees less timing at redline and ~200 load. There's a BIG difference in timing maps between 91 and 93.

Try this... leave the timing where it is, but lean it out a bit. You're still running the stock fuel map right? I helped a friend develop the fuel map for his completely stock X on 93, he goes by 'coevolve' on the forum. Hit him up if you want.

blk-majik

iTrader: (6)

Yes, everything else is still stock. The main thing I'm trying to gain here (above eliminating the knock) is to better understand whats going on at a lower level. So you're suggestion confuses me a bit, since heat is a contributing factor to knock and leaning out the AFR will increase heat. In the case of a stock X, whats causing the knock? Is it detonation due to hotspots, or is just because the timing is advanced to the point where the pressure peaks against the piston before TDC?

jrsimon27

iTrader: (1)

dont worry from 1 to 3 counts of knock is nothing and its normal

and for a stock car you have a lot of power wow

spdracerut

iTrader: (2)

Well, I'm thinking that it might be so rich that you're getting incomplete combustion. So maybe some fuel is burning later, after the exhaust valve is open, causing odd knock issues.

I figure you might as well try this as you've already reduced timing. If changing the fuel does not work, there's only one thing left to do, and that's to reduce the boost.

I had the same issue on my 2005 Evo at peak torque. I tried reducing the timing a LOT, added quite a bit of fuel and I still got significant knock (4+). I ended up just reducing the boost and voila! No more knock.

blk-majik

iTrader: (6)

I'll give it a shot and let you know how it goes, thanks! Looking at a few of the ROMS floating around, it's pretty safe to say that there's definitely more than one way to skin a cat

HybridKOOP

iTrader: (3)

I am in the same camp as you. Stock, I could actually hear audible knock. I quickly added a bunch of AMS stuff at 500 miles into owning the car, and flashed to a COBB AP Stage 2. I got a lot less knock then, and now have an FP Red turbo, etc... and am still trying to defeat the knock monster that lurkes in EVO X's. I have a COBB AP still, so my system doesn't count knock events per se, but my car likes to pull about 1 to 2 (max) degrees of timing above 6500 RPM. We pulled 5 degrees of timing out EVERYWHERE, only to still see knock and timing being pulled. Less, yes, but still some. Very annoying.

- Lou

derekste

iTrader: (9)

Are you using the latest 0020 ROM? The car should behave much better near redline with this reflash.

blk-majik

iTrader: (6)

Yes, I'm running 0020. I'm in the process of understanding how the knock sensor works. A mechanic friend is going to help me hook it up to an oscillioscope and run some test. We think it might just be a false-positive report due to vibration at that RPM range.

Does anyone know if the knock count that is reported represents the number of knock counts in a sample period, or if it's the intensity of the knock?

Hiboost

iTrader: (9)

If you do some searching of the forums there should be several threads about this very subject. It's VERY common for cars to have occasional or even consistant knock in the 6000-7000 area and this will vary from car to car. 1-2 counts that doesn't respond to reductions in timing is basically nothing to worry about. Usually 3 knock counts = 1* timing pulled so if removing 1* or 2* timing (which should remove 3-6 knock counts) doesn't correct the knock, you will be chasing your tail trying to get rid of it.

The factory tune is definitely run extremely RICH with relatively high timing which is usually not the best path for consistant power. Stock Evo X's usually hesitate and buck during acceleration from the rich tune so if yours isn't doing that (or right on the edge) it could be why it's performing so well in stock form.

Tuning 101 guidlines:

Before you touch anything get a good baseline of your current setup and make several backups of your original ROM tune. Then decide if you want to start with a baseline rom to speed up the process or modify what you have from scratch. Next a safe start is to reduce timing 3-5* in the 200%+ load cells with less reduction than stock as the load increases. At this point you can load in decent intake and exhaust MIVEC maps that are known to work well with your setup. Then make sure your cruise LTFT's are as consistantly close to zero as possible, probably +-3% is a good target. These LTFT's will apply the fuel changes to your Open Loop (WOT) operation so knowing that they won't change significantly is key before you can proceed.

With Timing reduced and LTFT's in the proper area you can lean the car out to your target 11.0 - 11.5 AFR by adjusting the High octane fuel maps leaner keeping in mind the value in the tables does not in all likelihood equal your actual AFR. Making smooth fuel and timing transitions is also a good plan to avoid triggering knock that otherwise wouldn't occur so avoid sharp changes in adjacent cells. Keeping the car leaner during spoolup can help response, usually aim for 12.5 AFR during spool and it should taper to 12.0 or richer as you reach 20 psi. There are many other steps to smooth out the maps but I won't get into the finer details, the critical point is that you have to log and verify how your car is responding to the changes you make.

If you are going to possibly run multiple boost levels (ex: 24 psi vs 26 psi) then your load % may change 20% or more so getting the AFR's dialed in for all of the loads you might see is a good idea. Then you can increase timing 1-2* at a time and verify there is no knock or only the 1-2 counts here and there. Once you consistantly get 3+ counts of knock in those areas then reducing timing 1* again should get you back to the limit and this threshold may be different at every RPM point. You can leave the car at the knock threshold or reduce it another 1* (or more) as a safety measure if you anticipate harsher conditions or inconsistant gas. Making small incremental steps and logging to verify results is crucial unless you've done numerous tunes and know what to expect. If your head is spinning at this point and you don't want to invest the time to learn all the details then contacting a professional tuner is a wise idea.

That's just a 5000 foot overview of the steps involved with tuning these cars, any advice is at your own risk so verify that your car is responding the same way before assuming anything.

blk-majik

iTrader: (6)

Great input, thanks! Thats the kind of experience I'm looking to gain first hand, but its nice to hear it in a newb-friendly context The bad part is that that's not what I've seen so far. Like I mentioned, reducing timing advance 1-3 degrees (tapered smoothly) actually caused MORE knock counts. Thats why I'm looking into how false positives are registered now. It's more an exercise in understanding than it is an exercise in eliminating knock at this point. The overall view you provided is very hopeful, thanks!