11.8:1 is not "lean."

People need to stop getting past the stigma that "X AFR" is ideal. Every motor is different. My old stock 1.6L with my GReddy liked it around 11.8-11.9AFR (no knock, good timing) whereas my new built 1.6L likes it a bit richer around 11.6AFR.

 

Theres some LS coils for sale right now IIRC in the FS thread.

 

As the seller of those coils I whole heartily agree that they would be an awesome replacement for him.

 

ha

 

Agreed. I threw the .040 gap out the window as soon as I read it. I have been down the spark blow out road before, and .025 on yoda caps with NGK BKR7ES-11 s results in no miss thru all rpms up to 24 psi for me. Someday I will get something better for a bigger gap, but it works.

In the past few days I rechecked base timing and did some data logs. Timing light, MS, and my orginal timing scribe marks on the CAS all state 10 deg at 900 ish rpm.

Secondly I don’t know why KnocksenseMS gets a bad rap up here. Mine works great. When I heard knock the little blue light from KnocksenseMS was lit as well. I have to admit that in the past I wondered if it was giving false readings, but the tuning I did with the suggestions up here resulted in a positive LOUD knock and a confirmation that KnocksenseMS works.

Tonight I did back to back runs, on the same strip of road, and the results are to follow. I left KnocksenseMS on so you could see where it knocked. MS pulls 1 deg of timing for every sec of knock. Note that KnocksenseMS is triggered by my TurboX RFL blow off valve, which is noted in MegaLog Viewer when the TPS goes from 99 to 0 rapidly.

 

First run. Lean VE table and medium timing.

Notes: Very audible knock at 13 psi, 11.3 AFR, 12 deg. Tried to boost twice, got same results, and called it quits due to loud knock.

 

Second run. Proven rich VE table and same timing from first run.

Notes: Lighter audible knock with fluctuation across RPM range. Able to hit 21 psi.
1st run trouble area no knock, AFR 10.5.
Audible knock at 18 psi, 9.8 AFR, 11 deg. Knock due to being too rich? Fuel knock? Immediately reboosted for run 2_b.

 

Second run b. Proven rich VE table and same timing from first run.
Notes: No knock fluctuation. Able to hit 21 psi.
1st run trouble area no knock, AFR 10.2.
Able to hit 21 psi. Audible knock after peak psi at 19psi, 10.2 AFR, 11.5 deg. Knock is due to fuel knock?

 

Third run. VE table and aggressive timing (Pretty much a copy of Braineacks map at link above).
Notes: Loud Knock. I would not go past 7 psi. Loud knock 7 psi, 11.6 AFR, 24 deg.

 

Forth run. My original tune.
Notes: Zero knock fat AFR.

Time for bed, but it looks like my ride likes an AFR around 10.5. Looks like I can get a bit more advanced – may be 11-12 deg max at peak torque. Thoughts?

Finally thanks Faeflora for the reminder of NGK race plugs. Keith at FM mentioned them a year ago and I totally forgot. I have some on order. As a tip Rock Auto sells them for $1.69 each. I will be curious if these allow a bigger gap, and might alleviate some knock. More to come.

 

KnocksenseMS is incapable of picking up light knock at peak torque without also throwing false positives for engine noise at high RPM. If you turn the noise filter up high enough to avoid the false positives, you will never pick up the midrange detonation. This is a huge, huge problem because detonation usually happens at peak torque.

The fact that your blowoff valve sets it off should be a pretty good indication that it can't be trusted. If it only picks up audible knock, then it's completely useless - the point of a knock sensor is to pick up the light knock that you cannot hear with your naked ear.

In order to solve the noise problem, you need a 2D filter map that alters the noise filter based on RPM. This gets you a lot closer, but it's still not perfect.

From there, you want to filter based on resonance frequency. Knock waves will resonate at a particular frequency, based on the bore diameter of the engine. Any other noise caused by an exhaust rattle or other vibration that happens at a different frequency will be filtered out as a false signal.

Once that's done, you want window filtering. Peak cylinder pressure occurs at 10-12*ATDC, so knock only occurs at a specific engine position - something like 10*BTDC compression to ~40*ATDC power stroke. If the noise occurs at some other position (i.e. valvetrain noise at 60*BTDC compression), it's obviously not knock.

If you have frequency filtering, 2D RPM filtering, and window filtering, the next thing you'd want is wave form filtering. Instead of listening for a resonance, waveform actually looks for a particular sound pattern, making it incredibly accurate.

The best way to detect knock is using piezoelectric pressure sensors tapped directly into the cylinder bores. OEMs are using this to do factory calibrations, but it's still a little pricey for enthusiast use (last I heard it was ~$80k for a full 8-cylinder diesel logging setup).

The poor man's knock sensor is either a set of mechanical det cans (do a search, it involves a 1/2" copper sweat, some nylon tube, and a set of construction earmuffs) or a set of electronic det cans (basically a speaker with an amplifier circuit and headphones.

To answer your original question, you shouldn't be pinging at those boost/timing levels. If you're knocking on 12* at 13psi, you've got other issues. Is your compression really 9.8:1, or was that a typo?

 

I agree with savington. If the bov can cause your knock sensor to go off, you need to throw the knock detection in the garbage and get something better.

 

Not a typo. I already addressed this earlier in the thread.

 

I had knocksense for about a week and removed it because my ears do a better job. constantly false positives and had to filter everything about like 5.5K, and everything below 2K, so it was pretty pointless.


I'm not sure about 22psi, but at 15psi (and im pretty sure people have gone above) the toyota cops are powerful enough to keep the plugs gapped at .040". You want the largest-gapped, hottest-temp-range plug you can get away with.

 

Yeah but tuning is different at different levels of boost.

Guys, his BOV is not causing knock.

That is "lift on shift" knock. That is the driveline slamming around when clutch is disengaged at high load and high RPM. If your logging has enough resolution you would see the knok occur -after- or right when the throttle goes to zero.

Rabbit, there is a very important thing about tuning:

You use sensors to tune. Everyone has different sensors. A lot of the time the variances between people's tuning maps is due to variance in sensor calibration. What I mean is you can not always tune by the numbers. On a knock limited fuel, you gotta tune to what doesnt knock.

My second point is that your sensors might be miscalibrated. If I were you Inwould recalibrated your AFR sensor and recheck base timing.

Btw as a data point, at 24psi on my old turbo, at 5000rpm I only ran 12 degrees of timing. By 7000, though, I was running 20 degrees. At 12psi and 5000 I ran 19 degrees. 93 octane though. No w/i.

 

Something is not right, you should be able to run 11.5:1 and not knock. I suspect part of this is compression ratio related, but I think it should take more spark than it is.

Check your static spark timing, check the wiring on your WB, reset, re-scale, and re-calibrate the WB, install BKR7E plugs, stop logging knock because its reporting BS, listen with det cans, get back to us.

 

I disagree that knock is reporting bs.

 

Have you used knocksenseMS?

 

use some det-cans to correlate with the data the knocksensor is outputing.

 

Please explain how he is able to tune out the "knock" then.