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Road Tuning - Knock question - AEM Infinity

Road Tuning

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Discussion and questions related to the course Road Tuning

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I'm going through the road tuning process in order to better understand the process and sort out any problems before I have the engine dyno-tuned by a professional. It would be awesome if someone could help me understand my log file, specifically in the knock department. Whenever I log pulls, it seems as though AEM is detecting knock and wanting to throw in more fuel to compensate causing a deviation from my target AFR. I can see this when I plot AFR Target and AFR Target Table against each other. I have attached my log file / basemap tune.

What I want to understand is:

How much knock is too much knock?

Is it engine noise or knock?

How to compensate for my problem (take timing out of the ignition map where I see knock?)

Should knock values/raw data increase with increased rpm or should they remain constant?

Thanks for your help! I would like get this figured out so I can either rebuild the bottom end if I need to or continue on with the tuning process.

Just some background to what I have done so far:

-Engine is a freshly built 1JZGTE, single turbo

-Single wire OEM knock sensors are being used.

-Loaded and modified a 2JZGTE basemap to suit my needs

-I have road tuned the VE table up to 5000rpm.

-I have not touched the ignition map yet.

-Only running on wastegate spring pressure, 11-12psi

Attached Files

I have the exact same question in a Sr20 tune, Bump!

I own a jzx100 1jz gte vvti. Okay your threshold looks like it’s set at a constant value. U need to understand with more rpm and load there is more noise therefore values will go up too me It looks like threshold hasn’t been set up properly. U need audio knock detection equipment too know if u hv knock especially if threshold hasn’t been set right. With knock u need to act fast especially at high rpm and load however down at low rpm and engine load it won’t suffer badly.

ANDRE has made webinars explaining knock and how to set up properly man knows wat he is talking bout hope that helps use

Hi Austin,

I have never used the AEM knock control, although first thing I noticed (As Andrew said) your threshold value is a flat line, this needs to increase with rpm. To determine what your threshold needs to run at you do need to have some knock ears so you can confirm knock and see what the levels reach.

I have attached a couple of webinars below for you which, although on different ecus, should prove helpful.



Ok, I watched both webinars about knock audio as well as read the AEM infinity manual on how to calibrate the knock floor. Theyre instructions suggest temporarily taking out 2-4 degrees of timing, and adding 10-15% fuel in the ve table then doing a third or fourth gear pull. The log should serve as a baseline where there is no knock and then you can roughly adjust the curve of the floor using the logged values.

As for knock listening equipment, how would I go about making my own setup? Do I take one or two Bosch knock sensors and wire them up to an amplifier running on a 9v? Or can I tee off my existing knock sensors with the use of a couple capacitors to prevent noise from back-feeding to the ecu? If making my own is out of the question what is a good kit that is reasonably priced?

Thanks for the advice guys, i'm learning a bunch!

That should work and you should find that the threshold should increase with rpm. There should also be a little bit of a buffer from the cylinder levels to threshold. To test you can then introduce a little bit of knock so you can see the spike and ensure the system works.

I have attached an example from a log I have. This is from a Spitfire replica plane I tuned with an LS engine. You can see the bottom section shows the knock levels and the threshold. The threshold moves up and down based on rpm, so does the levels.

This particular engine was having mechanical issues on cylinder 5 hence the excessive noise.

There is a couple of links below to people asking about knock gear

I personally use the Link knock gear and have for many years with great results.




Attached Files

In order for us to see your log on AEM Infinity, you need to upload both the .itssn file which you have attached but also need the .itlog file.

I own a 2JZ and can tell you first hand the stock knock sensors are terrible. Swap them out for a single Bosch wideband knock sensor to get more clear knock signals, making it easier to differentiate noise from actual knock.

We usually reply within 12hrs (often sooner)

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