Direct Scan help

[chrisgarrett46]

I can't seem to find two items in my DS handbook.
1. How do you zero out the knock count on startup?
2. How do you delete old files?
Can someone inform me please?

[Steve Wood]

Never knew you could zero the knock count...don't know why it matters? Timing retard is the vital number.

Go into My Computer to the DS folder and delete the files.

[Doc1of7]

Originally Posted by chrisgarrett46

1. How do you zero out the knock count on startup?

As I recall there is no memory, for knock counts.
ie it starts at 0, at start up. If you have a high KC generated during first start, or cranking, something is rattling, or a *fractured* serpentine belt (least from what I'se seen).

[chrisgarrett46]

Why wouldn't you zero-out the knock count? Whenever I go out in the car I have to remember what the starting knock count is so I know if it knocked while driving. Sometimes DS doesn't agree with SM or knock sensor. I notice when I start the car it will have a given knock number that doesn't seem to correlate to the last time.

Also, if I to into the files while DS is running and try to delete a file, it won't let me. It says "delete file?", I say yes and it doesn't delete. Anyway, I just did it the way you suggested and it worked. Thanks

[Doc1of7]

Originally Posted by chrisgarrett46

Why wouldn't you zero-out the knock count? Whenever I go out in the car I have to remember what the starting knock count is so I know if it knocked while driving. Sometimes DS doesn't agree with SM or knock sensor. I notice when I start the car it will have a given knock number that doesn't seem to correlate to the last time.

Why would the ecm want to remember it?. Unlike the BL it isn't a learned item.

How much actual timing retard is showing?.

[chrisgarrett46]

Originally Posted by Doc1of7

As I recall there is no memory, for knock counts.
ie it starts at 0, at start up. If you have a high KC generated during first start, or cranking, something is rattling, or a *fractured* serpentine belt (least from what I'se seen).

Geez, it never occurred to me that it was picking up knock on startup. Everytime I looked at it it had 2-3 knock counts and I thought they were from the last time. Dumb. Sorry.

[Steve Wood]

The starter engaging is usually the source of initial knock count...that is a pretty good bang.

You can always go backwards in DS to see if the knock count was in existence before the run as well as watch in as you page thru the frames.

Knock count does not necessarily have any correlation to detonation . As discussed here frequently, knock counts are filtered, analyzed, etc. by the ecm before the ecm determines if they might actually represent detonation and begin retarding timing.

Also, as we have frequently discussed, timing retard can occur from some other source of noise that happens to fall within the passband of the esc module. That is the reason I always harp on looking at the pattern of the timing retard to determine if you actually have detonation.

To date, I have yet to ever see any evidence of detonation on any of your DS files even tho you constantly tell me that you have detonation.

[chrisgarrett46]

Okay, I won't beat this to death, but I've been meaning to clarify this with you. When you say that real knock will increase or get worse with time, do you mean in a single episode, or do you mean over a series of episodes it will get worse? Sorry to keep going over this, but I'm just trying to get it all straight. As I do these DS files and SM and DS tell me I've got kr, it scares the hell out of me. I don't want to do something dumb and hurt my car.

[pacecarta]

in ds when you save files they usually get put on the dektop, and when loading files DS go to those first,
in windows you can mange files as you would any other , create a folder on desktop and drag and drop the ones you want to save into that folder the ones you dont want delete as you would any other file

i keep a seperate folder for each car and when I save a file i find the date and run # works great for filemane , and put as much info as you can about the file in the comment section when you save the file like the stuff DS doesnt record like launch boost , run boost , fuelpressure, tires , 60' 1/4 1/8 et , MPH , alky setting ,egt ,did you spin .


Knock can be picked up on startup , at burnout ,at shifts , and when spinning tires and DS records these as knock count , if you scroll through file and knock count doesnt rise during run than you were knock free

knock retard (spark retard) is if there is a sufficient count of knock or a severe enough konck than the ecm will retard timing based on severity and DS will show this as degrees of timing retard .

the knock sensor is essentially a microphone , think of it like your desk at school , tap on it once or twice light no one cares , tap on it constantly and youll get the attention of the teacher , bang on it and the whole class will turn and look

if you see knock come up and contiinue to rise and not go right away especially in third gear then you had knock and should change something in your tune , (more fuel, less boost , less timing), you can get knock retard in second and not third but usually only if 1-2 timing is too high and this lik third gear knock you should change tune to eliminate

if you see knock at a shift point and it goes right aay it could be driveline
if you broke tires and see knock it could be driveline shudder , try not to break tires loose , it looks cool but costs money and when trying to go fast it costs time

[Steve Wood]

What Paul said, except that I would have said "Noise that is reported as knock" as the majority of his examples are not truly detonation (knock) (Nor did he mean they were )

With regard to your question regarding my comments that true detonation increases frame to frame:

True detonation does not begin in a full blown form instantaneously, but, rather, begins small and increases in magnitude in time. This time is generally very small, and, that is why DS is such a valuable tool for analysis as it is capable of some 18 samples per second rather than approximately one sample per 1.4 seconds as scantools that use the ALDL port are capable of.

Now, this increasing detonation rate is reflected in the scantool by the increasing number of degrees of timing retard that are reported while detonation is occuring. The ecm decreases timing in an attempt to head off damage from detonation. It will not be successful if detonation is severe.

As an example, DS reports:

Frame 25- 1.0 deg timing retard
Frame 26- 1.8 deg
Frame 27- 3.0 deg
Frame 28- 5.2 deg
Frame 29- 8.0 deg
Frame 30- 12.0 deg

and so onward....

To me, that is a sure sign of true detonation as once it starts, it seldom stops until something pops, or one lifts off the gas. Occasionally, if one encounters a little detonation at the top of a gear before the shift, it may go away after the shift if it was minute in magnitude. Not always.

False detonation may appear such:

Frame 15 4.0 degs
Frame 16 3.8 degs
Frame 17 3.0 degs
Frame 18 1.9 degs
Frame 19 1.1 degs
Frame 20 0.2 degs
Frame 21 0.0 degs

As Paul exampled (find that verb in Shakespeare), false detonation, or false knock, is the ecm's misinterpretation of some extraneous noise that happens to fall within the esc module's frequency passband, and, which passes the ecm's algorithm for detonation. As it seldom is an ongoing event which continues to trigger the ecm's response, the timing retard is tapered out as full timing is restored. The rate of timing restoration may vary from chip to chip according to the programmer's whim.

Note that the above examples are intended as examples of patterns, and, the actual numbers may vary according to perceived magnitude of the event being dealt with.

Also understand that actual detonation seldom disappears without a significant change in the events that created it. It is a lot easier to prevent than it is to stop once set in motion.

Now is the time to ask what detonation is if you don't know.

[Steve Wood]

When I see one of the above patterns, I look at all the other parameters for clues as well when I make a judgement...were the o2s taking a dive, did the voltage drop down, did the coolant temp jump, did the converter lock, did the tranny shift, etc.

[chrisgarrett46]

Thanks Steve and Paul. I appreciate the explanation.