Using ignition trim for cylinder knock on boost & WOT AFR's

FlashPro questions & answers specific to the 2007-2008 Acura TL
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Yungone501
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Using ignition trim for cylinder knock on boost & WOT AFR's

Post by Yungone501 » Mon Jun 03, 2013 10:03 am

I have an issue where there are knocks detected on cylinder 1 and sometimes on cylinder 3. I am new to tuning but understand it pretty well as I have background in automotive fuel management diagnostics and repair so am not oblivious to most things on FlashPro. I read the help files on many of the problems Ive ran into thus far and have managed to solve them but this issue I wanted to ensure I understood before modifying any tables.

Basically, if my datalog reads that ONLY cylinders 1 and 3 knocked, I should trim -1.0 (retard) off each cylinder until I no longer see any knocks recorded in the datalog right? Also, I can add +1.0 (advance) any other cylinders (2,4,5 and 6) and continue to advance until a cylinder knocks...at which point I back off (retard) 1 degree correct?

If the methods above are true, can the same be done for the low and high ignition tables? Would it benefit me to (starting at far left column) slowly advance the ignition one degree at a time until knock or power loss is detected and then back off a degree on that column? I could maybe even do this first and THEN use ignition trim to fine tune the table.

Or if anyone else has any better solutions/ideas on knock control, Id be happy to consider any logical approach.

And also one other question, Ive noticed that my AF ratio in datalog doesnt meet my table value for WOT fuel values. Datalog shows that if I have my AFR set at 11.50 at a specific RPM and MAP value, the actual AFR may be 13.30 and slowly drop over 2-5 seconds while sometimes spiking again between under WOT. What causes this sort of air/fuel inconsistency during WOT pulls...ignition maps?

Thanks in advance for all the help.
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Hondata
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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Hondata » Mon Jun 03, 2013 10:41 am

I would retard the ignition for cylinders which show knock, but don't advance for the other cylinders. With less knock the knock control will drop and the ignition will advance by itself.

The WOT compensation tables are not target lambda tables - it is not logical to many people, but that is how the WOT compensation tables work.
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Yungone501
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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Yungone501 » Mon Jun 03, 2013 12:03 pm

Hondata wrote:I would retard the ignition for cylinders which show knock, but don't advance for the other cylinders. With less knock the knock control will drop and the ignition will advance by itself.

The WOT compensation tables are not target lambda tables - it is not logical to many people, but that is how the WOT compensation tables work.
I just got back from trying this and it helped but I seen that you posted something about zeroing out the knock limit and retard tables before adjusting ignition timing. Should this be done BEFORE fine tuning this issue with knocks im having?

As for the WOT AFR, this seems like a bad thing for the engine (especially while boosting 9psi) because very rarely does it ever stay at the set target. I would understand slight variance but 1-2 points higher than target sounds unsafe to me....thoughts?

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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Hondata » Mon Jun 03, 2013 1:05 pm

I still would address the cylinder trim first, then look at reducing ignition timing in any spots with knock.

Repeat after me: the WOT compensation tables are not target AF tables. You will need to tune the fuel tables (not the compensation tables) to get the correct AFR.
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Yungone501
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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Yungone501 » Mon Jun 03, 2013 1:18 pm

Hondata wrote:I still would address the cylinder trim first, then look at reducing ignition timing in any spots with knock.

Repeat after me: the WOT compensation tables are not target AF tables. You will need to tune the fuel tables (not the compensation tables) to get the correct AFR.
On the ignition timing thing, how am I reducing ignition timing to make knock disappear if I already did this with the trim first? I'm confused on this.

And for the WOT AFR, sorry. I obviously missed that statement earlier. But I get what you're saying about Making finer adjustments in the fuel tables. I'm learning here and I appreciate you helping me.

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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Hondata » Mon Jun 03, 2013 3:56 pm

While some cylinders are knocking more than others, reduce the ignition trim for those cylinders up to a max of 2-3 degrees.

Then datalog and look for specific areas where you get knock, and reduce ignition on the ignition tables in those places.
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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Yungone501 » Mon Jun 03, 2013 5:20 pm

Hondata wrote:While some cylinders are knocking more than others, reduce the ignition trim for those cylinders up to a max of 2-3 degrees.

Then datalog and look for specific areas where you get knock, and reduce ignition on the ignition tables in those places.
Almost ALL knocks have been removed and I was amazed at what difference it made in power and drivability. After changes were made, I had to go back in multiple places and add roughly 15% fuel to the low speed table. Then I did what you suggested in the WOT by going off of a few datalogs and cleaned this up too. Seems like the more you clean things up in the ignition, everything else looks and IS so much better.

Why only retard a max of 2-3 degrees in trim?

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Re: Using ignition trim for cylinder knock on boost & WOT AF

Post by Hondata » Tue Jun 04, 2013 8:14 am

Usually 2-3 degrees makes a large difference to the amount of knock, and more than that would start to create more cylinder unbalance.
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