Cobra289

I have a 165 with MAF $6E and I use the code APYP in my 305 car (APYP is for a 350).
I am interested to know what it is the "Forced Knock" and how can I get rid of this.

I am doing my SA table now looking to the data logging at a determined LV8 vs. RPM, when I see a determined retard, this value I change to my SA.
Is that the correct way?
Regards,
Cobra289

dimented24x7

iTrader: (2)

The forced knock is when the ECM adds in alot of advance to force detonation to test to see if knock can be detected and the ESC hardware is working properly. If you disable the bit in the diag. mask that corresponds to the ESC error code the forced knock test should be skipped. Dont know where that is in your ecm's mask but it seems like the standard tuner definitions should have it defined.

dimented24x7

iTrader: (2)

heres what youll want. This is the $6E 'ARAP' and the mask byte should be at 0x1DF in the bin. Disabling code 43 should cause the test to be skipped if I remember correctly.

Cobra289

OK. I am not a code expert but I found that my APYP hac got the same information see below:
So I need to change the bit # 4 and in my case (1111 1101) to (1111 0101) is that right?
In decimal the 1DF is 253 = $FD and should be 245 = $F5
So I can change that via HEX editor of TunerPro RT
Regards,
Cobra289

Cobra289

Hey! I start to like this CODE thing.

I found that it will add 10 deg SA to test the knock sensor and EST:

The value at LC239 is $47, so how to disable that?
$47 doesn’t mean anything to me. Do I need to zero it?
Regards,
Cobra289

JP84Z430HP

From the way it looks, you can set LC237 to: $FF (max out the enable temp) to disable the test.

Is this test the only way to set a Code 43, or is there a circuit check also that would trigger the code? I know on some ECM's, they test the sensor electrically, and if it's unplugged, it will set a code, but the only ones I can remember for sure that do that had the ESC module on the Memcal, IIRC......

JP84Z430HP

I think I just answered this question. I just read the diag chart for a code 43 in a MAF TPI car. About the only way they tell you to test it is to tap on the block, and look at a scanner to see if it detects knock.... They say that the "Forced Knock" test is only performed once per engine start, and it has to be above 95C coolant temp to run it, unless it encounters knock before it gets that warm.....Have to look through the code to verify all this though, I've seen the diag charts be incorrect in the past!

Grumpy

Disabling the flag just disables the reporting, and results of what would normally be a code setting condition.

To full remove the test means, removing the test, not just the flag.

So you need to do two things, one disable the flag, and two disable the actual test.

Getting interested in code, makes Heroin, seem like a desire for something sweet. It gets real addicting. Specially when you start running code on the ecm bench, and see it work. Never mind the goofy smile you get when you get your car running on your own code.

dimented24x7

iTrader: (2)

In my tbi ecm, the forced knock test is performed once per run when in PE by adding 14 some odd degrees of SA, I think. Have to go look at it again to be sure. If knock isnt detected the computer tries again, but the next time around with 20 deg. Still no knock it sets the code 43 and sets max knock counts untill knock is detected or teh motor is shut down. Dont know how the other ecms work but with stuff disconnected, the knock counter will go crazy due to an open circuit so if things are unplugged itll set a code.

If there is a temp threshold then that could disable it as well. Youll want to make sure that it isnt used anywhere else as a threshold for other things that are knock related. Its probably not but ive affected other parameters by messing with stuff that I thought only pertained to one thing. Im not familiar with the '165 so check the hac.

dimented24x7

iTrader: (2)

Short on time at this moment but I took a quick peek at the code and it looks as though setting b4 for the code 43 or maxing out the threshold temp would cause the routine to be skipped or not run. Still would be a good idea to search out the mask and the temp threshold to be sure before you disable the forced knock test. I personally havnt had much trouble with the forced knock on my motor other then the first time I step on the gas itll nose over momentarily while the test is in progress but other then that it doesnt cause any codes to be set and its nice to know that the KS is still picking up something...

Cobra289

Grumpy
Yes it is nice to get some knowledge of the code. ECM bench is for the future, now is important to get a WBO2 to tune.
I will do both changes, disable the flag and the test, just for fun to see my abilities on code, and as you know with a Prominator it is so easy to change the bin to compare.
A couple of weeks ago my brother in low has helped me to understand how the processor works, so I have got my first lesson.
He took a “flip over” and start to mention things and draw some other things. Have look of the first lesson. (See picture)


dimented24x7
Thanks for your input, like I mention above I will do a test with both settings changed, but only for a short period. I am tired to get every time I start the car a 23 knock counts and I was thinking that changing the “Forced Knock” will help that.
Looking more in detail to my data logging and with your information about the code I come to the conclusion that it is the start motor that causes those counts.
See my data logging, the car start after 1.3 sec. but the start motor is still running.
http://www.donostia.demon.nl/csv.zip

It is nice to see how thing correlate:
Like at record 22
LV = 255; MAF = 8.6 gm/sec; FP volts = 7; O2 mV = 453 (ECM reference)
Once the engine starts:
LV = 42; MAF = 12.5 gm/sec; FP volts = 9.5; O2 mV = 107 (Sensor); [Knock count =14]


Oh I forgot that to change at “LC1DF” the bit 4 it should be 1110 1101

Regards,
Cobra289

Grumpy

Doc's reviewing it now.
He's copied it over to his Etch-A-Sketch for safe keeping.....