2013 Impala 3.6 LFX - Overkill 87 tune - audible pre-igniton under power

I got the Overkill tunes for my 2013 Impala a few years ago, ran well on the 91 tune. After switching to the 87 tune I can hear it pre-igniting (or pinking as I call it) under power / uphill.

I emailed Will a few weeks ago asking for help in solving this problem, have not got a reply.

The question is, how do I solve this problem?

I have the HP Tuners tool, I'm maybe hoping someone can help walk me through what data I need to collect, how to analyze it or what to look for, and what changes need to be made.

The other alternatives I have are to put the factory tune back for 87, or take the car to someone with a dyno and spend some money on getting it dialed in.

Appreciate anyone who might be-able to help me out.

Post the tune you are using now and a log file that includes knock retard in it.

Thanks for the reply.

After posting I had the thought that after I flashed the 87 tune, I didn't disconnect the battery to reset/clear any stored data nor do I recall it going through a relearn period. Couple weeks ago I did that, noticed that it went through the usual relearn period, after that I have not been able to hear it pre-igniting (at least), and it seems to be running better than before - since its winter I cant be 100% sure that has fixed it.

I'll capture a log next chance I get.

Quote:

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Originally Posted by 5FDP

Post the tune you are using now and a log file that includes knock retard in it.

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Attached is the tune and the log.

The car has just had 100k mile service done 2 days ago, new plugs, EFI clean, all fluids changed etc.

The fairly steep hill I can sometimes hear pinking is about 2 minutes in, after that just some random acceleration here and there on the streets back to home.

Hopefully that has useful data.

Attachment 143458
Attachment 143459

The random part throttle knock is likely going to be hard to ever get rid of. It could be real or it could be picking up vibrations.

The knock that shows up when you are deeper into the throttle it something you can try to work on. I'd personally try to make PE happen sooner to see if that stops the knock. Try lowering the throttle percent to 60%, lower the enable torque to 40% and the delay torque from 100% down to 40% as well. I'd be curious if doing that will help stop those knock spike around 3,000rpm and 70ish percent throttle.

The changes to the cam timing are bs. I spent several hours on the dyno with a 16 impala and the gm tables were spot on. Picked up 2-3hp moving the tables 1* or less only out toward the top end.

Every knock event occurs during high MAP and Commanded EQ=1. Seems to me an easy fix would be to adjust PE so that it comes online when it needs to. See attached.

You should be logging Cylinder Airmass to see where KR actually occurs.

Also, MAF looks like it needs some work. Log Mass Airflow Frequency so you can make corrections.

Quote:

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Originally Posted by SiriusC1024

Every knock event occurs during high MAP and Commanded EQ=1. Seems to me an easy fix would be to adjust PE so that it comes online when it needs to. See attached.

You should be logging Cylinder Airmass to see where KR actually occurs.

Also, MAF looks like it needs some work. Log Mass Airflow Frequency so you can make corrections.

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Thanks for the info and file. I'll look for and add those options to the logging next chance I get.

I used the tune provided by SiriusC1024.

Attached is the log from today with the extra options (hopefully I found the right ones!)

Attachment 144140

Same as last time the steep hill is around 5 minutes in, there was stop start traffic leading up to it from where I can stop somewhere and start the log. After that couple jabs on the accelerator here and there.

Today was bit warmer around 65F, didn't hear any pre-igniting, seemed like it ran a little better with the PE changes, but hard to tell :cool:

Ok. Put High Octane, VCP, and Fuel>Gas spark back to stock.

Quote:

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Originally Posted by SiriusC1024

Ok. Put High Octane, VCP, and Fuel>Gas spark back to stock.

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These all appear to be in Spark > Advance:

Base > High Octane
Fuel > Gas
VCT > VCP Spark

Correct?

Yep those. Did you change them? If you don't have a stock reference there's a 2013 Impala 3.6 in the repository.

Quote:

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Originally Posted by SiriusC1024

Yep those. Did you change them? If you don't have a stock reference there's a 2013 Impala 3.6 in the repository.

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I have the original factory tune I saved before anything was changed.

I'll make those changes, and get another log. Might be a few days again.

Here's the log after making the changes of those settings back to stock tune.

Attachment 144259

I also compared the stock tune in the repo, exactly the same as mine except for one flex fuel setting (mine aint flex fuel so is was disabled).

The VCT tables are different in the stock file. Did you put those back, too?

Quote:

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Originally Posted by SiriusC1024

The VCT tables are different in the stock file. Did you put those back, too?

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Yes these were set back to stock (double checked):

Spark > Advance:

Base > High Octane
Fuel > Gas
VCT > VCP Spark

Airflow>Variable Camshaft

All of the Airflow>Variable Camshaft settings back to stock, here is the log:

Attachment 144312

If it's at a stock tune and you're still getting that much knock then it's a mechanical problem. Check for oil in the intake, plug condition, and do a seafoam cleaning through a vacuum line.

100k mile service was done a few weeks ago (new plugs, EFI clean (intake was removed to do that), all fluids changed), nothing unusual was noticed or noted.

I might do the seafoam.

Thank you for your help, much appreciated.

Im sure this is much more powerful with the cam timing back to stock, the dyno showed 2-3hp gains with very small increments of adjustment. This was at 6-7k rpm with only losses shown at lower rpms.

The VVT change back to stock has it running noticeably smoother.

Power seems about the same. Maybe pulls up the steep hill with less effort, need to drive it more.