The stock ECU will pull timing as well as a couple of other things when it senses knock. The problem is that when you are modifying a car to power levels well above stock and tuning on the edge, even a little instance of knock can blow a motor.

That's why knock is one of the most important aspects of tuning and why people want a way to monitor it. Basically, you want to tune right up to the limit to where knock would begin to occur, but you wouldn't want to go any further. Even at stock settings and with the ECU pulling timing, etc, knock is bad for an engine. It is bad on the bearings, pistons, rods, etc. Even small amounts of knock over a long period of time can cause things like spun rod bearings, fractured pistions, etc.

Hope that answers your question,
Eric

 

i use pocket logger along with safc and flashed ecu. lets say i can view my curent ignition map in the flash ecu (which i cant), if i log timing, rpm and airflow/calculated load, it should show me exactly what degree, rpm , load that the ecu see at that instance regardless of how i have the safc set (because safc send fake signal to ecu but logger logs what ecu see). so i compare the logged data vs. my ecu ignition map regardless of the safc settings.

for instance, if my log says that at 5000rpm, my timing was 12 deg BTDC, and load was XXX, and i look on the ignition map at 5000rpm and load XXX, it should show 12 deg also (if i didn't have knock). if the ecu saw knock, it would have pull timing by subtacting from the 12 deg or use a seperate load column that have the retard timing value.

so basically, the logger will log what the ecu see, so you should be able to compare logged data to actual ecu ignition map regardless of piggyback settings.

 

Like i always say , i'm new at this . But when the ECU pulls timing (your refering to retarding the ignition so that the fuel doesn't ignite before TDC), wouldn't a ECU tuning be a way to fix your ignition and set your timing correctly ? I mean i have seen melted down pistons and rings just shot, but some of the problems to re-ignition (from what i have always been told) have to do either with carbon build-up on the wall and causing excess heat, poor fuel, or the major one timing being too fast and lighting off the fuel on the compression stroke . So, if you made a sensor that showed mild knock i see where you would be going with this thread, but why wouldn't the person that tuned the car set it up right ?

 

A good tuner should set it up right, but that's the point of this thread. You need to be able to log/monitor knock to tune right. And a lot of people like tuning themselves rather than paying for it.

And tuning 'right' is a relative term. Some people like to tune very conseravatively, while others like to be right on the edge. But, in the end, you need to know where the knock threshold is either way.

Eric

 

When knock elevates higher than the learned noise floor the ECU tries to pull timing or add fuel.

Once modded the engine environment may be out of range of the factory safety features. That or it wont be able to react fast enough to save the motor.

Normally you cannot hear or feel a few degrees of knock.

L2r99GST,

The XEDE has no idea what overall engine timing is. It doesn't have access to any OBD-II features. Basically it only allows you to adjust boost, timing, and fuel.

I am using this: http://www.auterraweb.com/scantools.html

Its pricey but you can use it on all OBD-II cars and I do alot of tuning for local fellas here.

 

does this system allow you to monitor knock through the obd2 scan port. the pocket logger does not, which i don't understand why, it can log every other sensors on the engine.

 

problem is, with using a piggyback....you aren't gonna have a stock-like timing curve to compare to. even with only the afc, where you can't actually pull or add ignition timing, you are passively adding ignition timing by pulling fuel because you trick the MAF signal and the car is put in a lower load cell. so, if you are pulling fuel with teh s-afc and your timing curve is the same as stock, the car is probably actually pulling timing out.

make sense?

 

do you actually have a serial port on your laptop, or are you using a serial -> usb adapter?

 

yeah, i understand that part, i've use vafc on honda vtec for a long time and it's always been a problem until i went with uberdata and crome. but the point is that the logger logs data after the safc does it things through the obd2 scan port. so you are seeing the exact data that the ecu see. hope you understand the point i'm trying to make.

 

the ECU sees a signal AFTER the afc....so, thats not right.

 

1. I cannot read knock. And even if I could I dont know what an acceptable noise level is. I read timing changes in relation to overall timing. Taking into consideration coolant temp, air temp, and air flow.

2. I actually have a serial port.

 

I've been looking at getting this product. Do you know what kind of sample rate the Auterra logger is capable of getting on the Evo?

l8r)