MyG37 - EcuTek and Knock Detection: Is your engine knocking?

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- - EcuTek and Knock Detection: Is your engine knocking? (https://www.myg37.com/forums/ecu-tuning-dyno-data/283628-ecutek-and-knock-detection-is-your-engine-knocking.html)

I worked at a small research plant for 27 years that did research on refinery processes. My father (BS Chemistry) was one of the founders. That's why I have a copy of the API Project 45 report. Had to learn to decipher MSDS sheets. Took a few semesters of college-level organic chemistry, too. Worked with Ph.D Chemical Engineers who were happy to answer my silly gasoline questions once I got into the Internet car thing.

Slatey:
How does the car feel with the tune?

Quote:

Originally Posted by SonicVQ (Post 4149008)

Slatey:
How does the car feel with the tune?

It feels great, I did a review of the tune on my sedan in this section with similar results. Totally worth it.

Guys I was just trying to boost octane, not die. Though I would have 0 knock because I'd be dead lmao

I tried torco, 32 oz to 12 gallons. Based off the mixing instructions it should be 100 octane.

Quote:

Originally Posted by Slatey (Post 4149095)

Guys I was just trying to boost octane, not die. Though I would have 0 knock because I'd be dead lmao

I tried torco, 32 oz to 12 gallons. Based off the mixing instructions it should be 100 octane.

With this safer tune, the knock is all but gone. I still see the odd event at when it is warm and somewhat humid, but only under heavy load.

I am gonna run with this for a while, in the next little while I'm throwing on resonated test pipes and see if more exhaust scavenging will make for cooler engine temps and less knock.

Gonna be an interesting experiment.

MORE DATA! MORE CAUSES OF KNOCK

So I installed a grounding kit (Big 3, etc.) and it caused some issues.

I went from a next to no knock to TONS of knock all over the rev range.

Temperature ranged from 70F-85F, high and low humidity, different gas stations, fresh oil, it didn't matter. I was getting knock events greater than 3* at different loads and RPM points.

All of that being said, I found this post by scarguy055

Quote:

This is a copy of something I posted on the DIY sticky for the grounding cables. Putting it here because this thread is more recent.

Connecting an additional cable from the battery negative terminal directly to the chassis bypasses the battery current sensor, which can impact the power generation voltage variable control system, possibly leading to improper battery charging.

If this causes the alternator to charge too often, it can cause battery over-charging, premature alternator failure and decreased fuel efficiency.

It seems to me like the additional ground to the negative terminal would cause the battery current sensor to see less of the current, making it think there was less battery use, causing it to under-charge. Not only is a weak charged battery an issue for multiple reasons, but on my 'vert could impact the top operation which is very sensitive to battery voltage.

Like many current sensors, the battery current sensor appears to be a "ring" that just sits around the factory ground cable. The factory ground cable seems very thin and the battery current sensor appears to have plenty of room to accept a much thicker cable.

https://cimg0.ibsrv.net/gimg/www.myg...119001e19d.jpg

Has anyone tried to replace the factory ground cable from the negative battery terminal to the chassis by running a thicker gauge ground cable through the battery current sensor?

I wonder if the decreased space between the sensor and a thicker cable would cause the sensor to incorrectly sense what it thought was a higher current, causing the alternator to run too much?

After discovering this, I removed ONLY the ground from negative battery terminal to chassis. VIOLA! All of that weird knock was gone, 100% back to the normal behavior of my tune.

I think the tolerances of my tune, plus the now inaccurate voltages, caused it to deviate enough to cause issues.

My conclusion is: if you are doing a grounding kit DO NOT ground from battery to chassis, bypassing the current sensor. Especially after a tune.

Genius! Shall we call you Colombo, Holmes or Castle?

Quote:

Originally Posted by slartibartfast (Post 4155830)

Genius! Shall we call you Colombo, Holmes or Castle?

https://cimg8.ibsrv.net/gimg/www.myg...8af7e46af3.jpg

Quote:

Originally Posted by Slatey (Post 4149094)

It feels great, I did a review of the tune on my sedan in this section with similar results. Totally worth it.

Your tune turned out quite well. Is it the same tune as the data log you posted earlier in this thread except for ignition timing?

Quote:

Originally Posted by jrb55gh (Post 4155989)

Your tune turned out quite well. Is it the same tune as the data log you posted earlier in this thread except for ignition timing?

It is. The tune was solid except for the knock, but that could be a number of factors causing that. Pulling 4-5 degrees doesn't impact power too much, so overall it is a very good tune.

I am looking at your posted data log and something seems odd. Compared the data logs for my ecutek tune you are running richer with less engine load and less timing but still getting ignition correction due to knock. Are you running 93 octane?

Quote:

Originally Posted by jrb55gh (Post 4156835)

That's where a lot of my initial confusion came from. The car shouldn't be knocking based on what I've read and heard. I am running 93. I've tried multiple gas stations, running octane booster, pulling timing, even doing WOT pulls in cool weather. I think something else is going on with the engine unrelated to the tune. It rarely knocks now with the current tune, even in warm weather, but I still see events greater than 3* every now and again.

Post what your logs look like if possible

Here is a data log from a month ago covering the same rpm range as your posted log. The cam timing data is not in this log, but afr, load, ignition timing, temperatures and rpm are. The knock you are experiencing may be caused by combustion chamber deposits in your 100k mile engine. Maybe some fuel additives to clean the combustion chambers and the backs of the intake valves will help.

Quote:

Originally Posted by jrb55gh (Post 4157086)

I gave it some thought and I think you may be right, I figured its likely one if a couple things: Carbon deposits or a vacuum leak.

I figured it could be carbon because it was definitely highway miles based on the amount of rock chips on my front bumper. I did a full seafoam treatment, one spray bottle for each throttle body (not simultaneously), and a canister in the fuel tank.

This seems to have definitely helped. I'm getting way less knock throughout the rev range on hot days. I say hot days because it was 92F yesterday and this has been the hottest day since I treated it and saw improvements since my last file update compared to prior hot days. Cool days dont produce much, if any knock, obviously.

My next plan of attack is figure out why I'm running lean compared to my target AFR. Your car is essentially right on your target AFR vs. Actual AFR for bank 1 and 2. My theory is maybe a vacuum leak somewhere. Unless my intake is bringing in that much air and dropping target AFR is the only way to compensate.

Since the purpose of the grounding kit is to reduce resistance in the ground circuit, you can simply attache to the same grounding point as the battery cable instead of directly to the battery terminal. This will direct all current through the sensor. The negative battery cable is sized for the starter current load, so the running current should be no issue.