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Author Topic: Acceptable limits for knock voltage  (Read 95344 times)
nupustas
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« Reply #105 on: July 21, 2022, 10:16:31 PM »

Updating my progress.
Made detcans, and can confirm what stroked engine is much noisier than stock (a have both cars, so no problem with comparing). Extra sound looks like from pistons(i think due to higher piston to wall gap, ant shorter piston skirt).
So first, i was right about fake knock - i can't hear any knock at low rpms/load, but ecu pull timing about 10 degrees. So what i done and where i ended(?) :

1. Set CWKRREF to 1
2. After reading FR, decided not to touch KFKEF maps at all, left it stock. Maybe it doesnt fit for stroked anymore, but without cylinder pressure sensors its impossible to set this values.
3. Made a lot of pulls 3/4 gear with different boost level and timing to find where real knock appears.
4. According rkrn values from from log without real knock, increased RKRMX1(2)N. This values adjusted after few puls, just to get point, there is no real knock.
5. Slightly increaseded boost level(with new RKRMX1(2)N values), and knock apears, but ecu also detects knock and pulled timing. This knock not continuous - appeared and gone (after pulled timing and extra fuel via KLAMKLRL). Log attached.

How do you think, did i do everything right?
« Last Edit: July 21, 2022, 11:11:25 PM by nupustas » Logged
R32Dude
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« Reply #106 on: July 22, 2022, 05:44:59 PM »

Best to do your own baseline for each cylinder and then use that to see whats going on.
Log ikr(i), vkr(i),rkr(i)

 Calculate 64*ikr(i)/(2^vkr(i)) . This is the instantaneous signal from the knock sensor for cylinder i.
Do the same calc for rkr(i).

Compare the normalised rkr(i) above to RKRMX1/2N (check which cylinder is mapped to which of these two maps). If the calc value or rkr(i) is< map then the map is never used, which is what you want really. You want the true rkr to be used, not some fixed map value which is there for safety.

Unfortunately, logging is usually not quick enough to catch the moment the knock occurs, but if you do these baselines when the load is partial, you can get the true knock free baseline of the motor and can start looking at the kek values that are now too close to the baseline due to the mechanical noise. You can also use the readings to make your own RKRMX1/2N maps as described in the FR.

Do make sure that B_krldy =1 under load in 3/4 gear first. It does a few things, 1) decrease knock sensitivity and 2 makes rkr(i) follow ikr(i) quicker. It does other things too.

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nupustas
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« Reply #107 on: July 22, 2022, 11:01:47 PM »

Best to do your own baseline for each cylinder and then use that to see whats going on.
Log ikr(i), vkr(i),rkr(i)

 Calculate 64*ikr(i)/(2^vkr(i)) . This is the instantaneous signal from the knock sensor for cylinder i.
Do the same calc for rkr(i).

Compare the normalised rkr(i) above to RKRMX1/2N (check which cylinder is mapped to which of these two maps). If the calc value or rkr(i) is< map then the map is never used, which is what you want really. You want the true rkr to be used, not some fixed map value which is there for safety.

Unfortunately, logging is usually not quick enough to catch the moment the knock occurs, but if you do these baselines when the load is partial, you can get the true knock free baseline of the motor and can start looking at the kek values that are now too close to the baseline due to the mechanical noise. You can also use the readings to make your own RKRMX1/2N maps as described in the FR.

Do make sure that B_krldy =1 under load in 3/4 gear first. It does a few things, 1) decrease knock sensitivity and 2 makes rkr(i) follow ikr(i) quicker. It does other things too.



Thanks for explanation. B_krldy =1 should be all the way during pull in 3/4gears ? From logs i can see what it =1 only at "noisier" load/rpm range.
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R32Dude
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« Reply #108 on: July 23, 2022, 02:34:40 AM »

It must be 1 before any knock is detected.
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nupustas
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« Reply #109 on: July 24, 2022, 01:19:38 PM »

It must be 1 before any knock is detected.

Thanks for help. I think i finished my knock detection. krndy trigerring exactly before real knock.

I bought supertech pistons without any coating, next time i think worth to pay more for coating; it should reduce extra noise and and maybe no need to bother with knock detection adjusting
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