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Title: Removing false knock caused by new exhaust Post by: R32Dude on June 16, 2022, 04:59:19 AM I replaced the MK5 R32 exhaust to the cats with one out of a MK6 golf R , which is straight bolt on job, but has no resonator.
Now I get small constant KR on one cylinder only. It's only -1.5 , but I know it is not real because when I retard the timing by 5 degrees it still want to retard by 1.5 every time. It only occurs when the muffler valve opens, which I set to 4500 RPM. I assume some pulses are interfering with the detection. What would be the usual way a tuner gets around this problem? Adjust RKRMX2N (this cylinder is the only one mapped to this) or adjust KE4N? I understand that RKRMX2N is only used when rkr > RKRMX2N * 2ˆ(vkr-6), so I need to log these to make sure, otherwise it is pointless to alter the map. Title: Re: Removing false knock caused by new exhaust Post by: prj on June 16, 2022, 07:58:20 AM Bump engine noise map for that cylinder is how you get around it. If you want it in laymans terms.
As to how it is modeled in ME7 I don't remember anymore. Also, are you sure that the -1.5 you see there is not adapted from previous runs? Does it knock and is actually detected every time? ;) Title: Re: Removing false knock caused by new exhaust Post by: R32Dude on July 06, 2022, 08:21:34 AM Quick update, Im still investigating. Not so sure it is the exhaust but it is not knock.
The retard shown is not triggered by B_kl which surprised me me. Adaptive kr is off, and wkra array are all zero when I dumped RAM the end of the log. Wkr suddenly gets a value of -1.5 and when it advances by 0.75 (when the counter hits zero), it is immediately brought back down to -1.5. Again, not by B_kl. I patched in some small custom code to log the B_kl by incrementing a counter, at free RAM location, as it is too fleeting for normal logging. Looking at IDA atm,alas very slowly. Title: Re: Removing false knock caused by new exhaust Post by: R32Dude on July 07, 2022, 12:06:32 AM Found the issue, LZ is active for that cylinder.
Title: Re: Removing false knock caused by new exhaust Post by: _nameless on July 07, 2022, 12:29:35 AM nice work
Title: Re: Removing false knock caused by new exhaust Post by: IamwhoIam on July 07, 2022, 02:59:36 AM Found the issue, LZ is active for that cylinder. What exactly do you call LZ? Title: Re: Removing false knock caused by new exhaust Post by: R32Dude on July 07, 2022, 03:34:43 AM Optional Leading Cylinder (LZ)
The leading cylinder function is enabled: - On exceeding a cylinder-specific speed threshold KRNLZ, above which the cylinder has poor knock detection, this cylinder is led by the cylinder with a good knock detection........ If the code word CWKRLZFK = 1, the retard for the led cylinder is determined according to the following minimum selection: i is current(led) cylinder, j is leading cylinder, WKRLZOF is the pesky -1.5 that kept rearing it ugly head. wkr_i = MIN (wkr_i, wkr_j) + WKRLZOF_i Title: Re: Removing false knock caused by new exhaust Post by: prj on July 07, 2022, 05:30:13 AM This offset is the per-cylinder offset for knock limit between the cylinders.
Can be positive or negative. Removing it can mean you can be knocking on that cylinder and the ECU will do nothing. I wouldn't randomly turn it off. |