Knock Sensor, Knock Filter, ESC and swaps!

[JeepsAndGuns]

Ohms have always been a weak point for me. Its one of the many things in life that confuse me. So I really have no clue what all those different settings mean other than it measures ohms in some way. I really have no idea what setting to use when trying to measure something, so I just try them all till it reads something. About the only times I read ohms is at request, like this thread. So I just post up what I read and hope the person needing the readings knows what the readings mean.

[JeepsAndGuns]

Using the link Robert posted in Jim's toyota thread ( http://www.phormula.co.uk/KnockCalculator.aspx ) to calculate what a engines estimated knock feequency is, mine came out to 5.4kHz. Are there any knock filters/sensors that match that?
If I'm reading that chart right, I saw 5 and 6, but nothing close to 5.4.
I get crap loads of false knock with my current setup using a 350 knock filter and sensor, and I even took and mounted the sensor in a brass elbow. That helped some, as I now get hundreds of counts instead of thousands, but still cant use it. I tried a 454 knock filter but I got more counts with it than I did with the 350 filter.

[EagleMark]

False knock counts are sometimes an issue in a conversion, or even an old motor that came with the knock system stock, can be worse on stock engine modified and even the noise of headers alone can throw them off. Heck on Thirgen they tracked down false knock to a bushing on rear axle control arm!

I don't know the answer?

I do know that just taking out the knock sensor and disabling error code in a 1227747 is killer if you don't get rid of the ESC test.

You could always build a safe spark advance table and take out knock sensor. But from memory in $0D can't remember if there is, or how to stop knock test?

[1project2many]

Understanding Ohms is simple. It's the "something" that doesn't want electricity to flow. Ohms is to electricity like kinking a garden hose is to water flow. The more restriction, the less flow in the hose. The more ohms in the circuit, the less amps want to flow.

But you don't need to know what Ohms are (is?) to take measurements correctly. Start with the lowest setting on the meter and move up from there. The lowest setting that gives a reading is the one to use.

The LT1 knock sensor is 5.2 kHz. That may be due to an excess of mechanical noise. The sensors get "excited" at the frequency listed so you pick the one closest to your engine and go from there. The other values in the chart such as , gain and offset probably describe how the signal is tailored to the engine but until I know more, they're just numbers. There are a few relevant SAE papers that probably tell the whole story. Anyone here a member of SAE??

Once upon a time I diagnosed false knock back to metal junk rattling around in the bed of the truck. Hard to believe in the knock system when stuff like that happens.

Many of the circuits and ideas used on these EFI systems were either designed by Motorola or by Delco engineers. There are two relevant patents which have similar artwork and some similar claims. The first is by Motorola and was filed in 1980. The second is from Delco and was filed in 1983. At qucik glance, the Delco patent appears to be a combination of the Motorola patent plus a means to actually adjust spark timing.

If I had some spare time I'd spend it trying to determine how closely the Motorola patent matches the knock filter in the memcal.

[RobertISaar]

But from memory in $0D can't remember if there is, or how to stop knock test?

later calibrations did away with the forced knock test.... 0D probably doesn't have it, especially if it's not in the XDF already. otherwise, would have to look around in the DTC43 area of the algorithm to see if there is a section that adds SA for a small amount of time as a test.

Once upon a time I diagnosed false knock back to metal junk rattling around in the bed of the truck. Hard to believe in the knock system when stuff like that happens.

WOW...... metal in the bed being detected as knock.... that's a new one for me. i have a bad lower engine mount causing some racket for me at the moment.

[1project2many]

The metal in the bed was in a 90 or 91 R / V style truck with an aluminum flatbed that was not mounted on insulators. It was loud, but GM school teachers had told me the sensors would only pick up engine noise. I wasted a bunch of time ignoring the obvious.

[Six_Shooter]

This is why I usually turn down the knock attack rate and listen for real knock. I don't trust knock sensors to be anything near accurate.

[EagleMark]

I'm just amazed at how many knock sensor paremeters there are in newer stuff? This is a 2002 so this is old!

[RobertISaar]

yeah, pretty soon after the transition to OBD2, the hardware filters went away... not 100% certain how it's done in those applications, but i've heard anywhere from the PCM doing really rapid sampling of the circuit to make a "noise profile" and when the signal strays too far outside of the normal noise boundries, it's considered knock(that's similar to how the hardware filters work from what i've seen) to extra hardware being permanantly embedded into the PCM(digital sound processor).

[JeepsAndGuns]

later calibrations did away with the forced knock test.... 0D probably doesn't have it, especially if it's not in the XDF already. otherwise, would have to look around in the DTC43 area of the algorithm to see if there is a section that adds SA for a small amount of time as a test.



WOW...... metal in the bed being detected as knock.... that's a new one for me. i have a bad lower engine mount causing some racket for me at the moment.

I was going to ask the same thing, does $0D have a knock test? Right now I have everything hooked up and "working", but have spark retard enable temp set to max and tuned my spark table by ear.
This old Jeep probably has no shortage of noise making components. Heck, the old T18 4 speed makes a audible click with each shift, and 3rd gear syncro is a little worn and the teeth sometimes hit on downshifts. So with that being bolted straight to the engine, I'm sure it picks up noise from it to. I just always keep having a feeling I will never have a properly functioning knock system. But that doesnt keep me from trying.

[34blazer]

WOW, looking at that KS freq calculator, im using the wrong sensor for my application. since im using the 3.1 v6 sensor on a 302, would that cause some false knock issues? doesnt seem to be too bad, just cant run more than 31* WOT advance without knock showing up, or going leaner than 12.8:1. anyone successfully use the LT4 knock filter and sensor? I saw an old thread on the TGO, but no real source for the filter.

[RobertISaar]

i've seen one person adapt the last-style knock filter to a 92-93 LT1 P4 MEMCAL and supposedly it worked... PM'd them a long time ago for info on what all they did, but no reponse.

those also have 8 legs that connect to the board, so i imagine all you have to do is match them up and swap the knock sensors?

[RobertISaar]

and here is another interesting image i downloaded long ago...

matches up 4 pins, supposedly those are the only 4 that do anything, just like the P4 applications? really don't know why GM used 8 pins in both versions if only 4 were actually useful. i have one from a 95 3.4 that i could pop open and take a pic of/look at if necessary.

then again, i'm about to study the P4 specific filters to see just why the other 4 pins don't do anything.

[EagleMark]

Man I forgot who did this for us and I never got it posted! Anyone remember the thread so we can give credit?

We should get a moderator to compile all this knock, memcal stuff in a thread?

[RobertISaar]

document shows an author of "Frank".