contrast
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« on: April 26, 2017, 01:40:11 AM »
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Hi all,
Having this issue with tip-in/transient knock. I have coded a knocklight into ECU to blink MIL when average retard is above threshold and
I can make it blink when i touch accelerator pedal little quicker than very slowly. Doesn't happen all the time, but more evident when engine is up to temp.
It happens even during idling and also <2000rpm range. Above that it's clear all load/rpm ranges. WOT is clean as a whistle.
I have googled and found it to be a common issue and somewhat dark matter. Nobody knows for sure... Maybe you guys do.
What have I done so far? Retarded timing by 5-6 degrees around the problematic area. Increased acceleration enrichment. No help still.
I was thinking limit throttle opening at lower rpms to counter sudden airmass spike?
It's definitely worrying.
I found only one log quickly where it is recorded at idling.
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« Last Edit: June 28, 2017, 10:00:56 PM by contrast »
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nubcake
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« Reply #1 on: April 26, 2017, 01:54:48 AM »
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Log AFRs, see how lambda behaves around the problematic area, play with %ESUK. Most likely too little "short-term" transient correction, so it doesn't enrich quick enough.
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contrast
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« Reply #2 on: April 26, 2017, 02:05:24 AM »
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I have played with ESUK maps. According to WB gauge, AFR drops to about 13ish and then resumes at stoich. In logs there are a few mildly lean spots sometimes.
Is there a delay parameter in ESUK? Quick glance at FR didn't tell about it.
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nubcake
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« Reply #3 on: April 26, 2017, 04:45:44 AM »
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AFR drops to about 13ish and then resumes at stoich. Depending on your lambda request, that might be too lean overall (not enough enrichment generally), but it definitely looks like there's actually not enough long-term compensation. Is there a delay parameter in ESUK? Quick glance at FR didn't tell about it. There are two components to the enrichment/enleanment basically: short-term and long-term. Firstly the total amount is determined, then the distribution between long and short-term (KFABAK out of memory, could be wrong). FR tells quite nicely about it, try a "long" glance at that section.  |
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prj
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« Reply #4 on: April 26, 2017, 04:55:19 AM »
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The real reason for this, is that your timing map on middle loads is too advanced.
Knock during transients is usually almost purely due to incorrect ignition timing. The fuel mix does not affect it at all when the engine is not super hot.
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contrast
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« Reply #5 on: April 26, 2017, 05:11:01 AM »
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I have reduced timing at 700-2500rpm and from low to mid loads. Currently ranging from 3-6degrees reduced. Just tested, during warmup its perfect, as soon as engine temp needle stops at middle, i get blinking MIL...
This is an 04 Volvo S60R if it matters btw.
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contrast
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« Reply #6 on: April 26, 2017, 01:45:33 PM »
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Any more ideas guys? I rarely ask for help, I try to figure stuff out on my own. But I'm truly helpless here.
Found a value DUKK in %ESUK, defined it it my file, it's 1.5ms. not sure if it matters to be honest.
Reduced timing even more. Delta from stock values is up to 12degrees.
Added more enrichment for acceleration. I'm starting to get inefficient, lots of pops and bangs. Fuel mileage agrees...
Still problem, once coolant temp reaches 80ish C, shit hits the fan.
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prj
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« Reply #7 on: April 26, 2017, 02:07:39 PM »
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Get some detcans and listen to the engine.
Maybe something is banging against the block when the engine moves in the engine bay, and actually there is no knock... ecu just sees it because something is hitting the block.
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contrast
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« Reply #8 on: April 26, 2017, 02:25:28 PM »
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I was thinking that (along with getting and setting up detcans), but would it not register retards at any engine temp?
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phila_dot
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« Reply #9 on: April 26, 2017, 02:35:17 PM »
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Seems everyone is ignoring the obvious here.
Look at dwkrz, not all retard is the result of actual knock.
It should jump out just based on the behavior in your graph.
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nyet
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« Reply #10 on: April 26, 2017, 04:03:30 PM »
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This? (B_kseb1 = 1 & B_kseb2 =1), erfolgt die Aktivierung der Sicherheitssp¨atverstellung (B_krdws = 1)
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contrast
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« Reply #11 on: April 26, 2017, 11:23:30 PM »
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I'm confused. Is it not for circuit error? B_krdws I mean.
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nyet
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« Reply #12 on: April 26, 2017, 11:31:55 PM »
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I'm confused. Is it not for circuit error? B_krdws I mean.
Yes, I thought that too. The other path I posted is one I don't know anything about. |
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contrast
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« Reply #13 on: April 26, 2017, 11:50:48 PM »
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Seems everyone is ignoring the obvious here.
Look at dwkrz, not all retard is the result of actual knock.
It should jump out just based on the behavior in your graph.
I'm open to the idea of it being some safety mechanism, but it puzzles me why is it active only at warm engine? |
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prj
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« Reply #14 on: April 27, 2017, 04:50:36 AM »
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There are also:
1) Knock adaptation value
2) Pre-emptive ignition retard during tip-in.
I thought you made sure it is actual knock.
Look at knock voltages and individual cylinder trims, not just average.
Do the knock voltages spike? If not, this is not coming from actual knock.
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