False Knock?

[Eqcj]

Hey everyone,

I've been learning tuning for a while now and decided to tune my Chevy Caprice. The car currently has the stock tune, and I installed a new VCM OTR intake along with a 3" exhaust and the stock catalytic converter. I started by working on the MAF, and I noticed the car was running very lean?it was showing 15-22% off. I also noticed I kept getting knock retard (KR) values of 1-3, which I initially thought was due to the lean condition. However, even though I'm almost done with the MAF tuning, it's still showing KR values of 1-2. I tried zeroing out the burst knock table, but nothing changed. I also reduced spark by a few degrees, but it?s still showing KR values of 1-2. I don't hear any knock, so could the knock sensor be too sensitive? It even shows knock at idle. I've paused tuning for now until I see the KR table showing zeros. I'm running 95 RON octane, which I believe is equivalent to 91 octane in the U.S.

I appreciate any support or advice!

[biholliday]

can we see the tune file?

[Eqcj]

I've attached the tunes. They're mostly stock tunes; I?ve only disabled the DOD and made adjustments to the MAF calibration, which is still a work in progress.

[Alvin]

That file, vin, etc. is weird.

Post the absolute stock file.

[Eqcj]

I?m from the Middle East, which is why it?s a bit different. The stock file is attached.

[JayRolla]

Not on my computer with hptuners so can't read the files. Do you have a wbo2 hooked up to see your fueling at wide open throttle? If so what AFR's are you hitting under boost? You say the car was 15-22% lean (positive fuel trim?) and fixed that. Did you also tune the MAF vs wbo2 error at WOT to reach your set power enrichment?

Also 1-2* timing pull is nothing to be really concerned about. Seeing it consistently on every pull is a bit strange and could be false knock.

[Alvin]

That is pretty bizarre. After it runs for a while do you notice any check engine lights? Scan for codes after it runs for a while? no codes are stored in start up.

[Eqcj]

I got a reading from my WB that the car is running 15-22% leaner than the commanded AFR all the time. The percentages are better now, but I'm just curious? is that normal? I know 1-2 degrees isn't much, but I keep getting that reading on 'Idle' and in almost every other cell

.

[Alvin]

that 1-2 degrees that it's pretty much constantly sitting at doesn't look normal at all. That isn't normal knock sensor or burst knock behavior.

I didn't see burst knock logging.. but you could log that to see if that is it.

[Eqcj]

Nope, I never got an engine light, and I don't see any codes.

[Eqcj]

I will try to check for burst knock next time I log. However, last time I zeroed out the burst knock table, and it still showed the same values

[JayRolla]

Looked at the logs now. I do see you have a wbo2 and didnt realize this was happening at idle or light throttle. Does seem very strange because its very consistent.

[Eqcj]

I tried zeroing out the static knock table and logged the data at idle while I was fixing the driver's seat, so I couldn't move the car. It looks like this fixed the issue. I then put the old tune back, logged all knock-related channels, and observed total knock retard values of 1-3, while all other channels showed constant zeros. However, I still don't have a clear understanding of the purpose of the static knock table. Can someone explain it to me? And should I just leave it zeroed out?

[JayRolla]

I tried zeroing out the static knock table and logged the data at idle while I was fixing the driver's seat, so I couldn't move the car. It looks like this fixed the issue. I then put the old tune back, logged all knock-related channels, and observed total knock retard values of 1-3, while all other channels showed constant zeros. However, I still don't have a clear understanding of the purpose of the static knock table. Can someone explain it to me? And should I just leave it zeroed out?

I believe this is static retard per cylinder at specific RPMs. From what I understand this can show up as false knock. In most OEM files I have seen this table is usually zeroed out. I know it is on my CTS-V. You should be okay to keep it zeroed. But let's also see what other more experienced members will say.

[Alvin]

Yeah that static knock table would be it.. It's ok to zero.

I've never seen that table populated with anything other than LT4 GEN 5's..

That is very bizzare but also seems like a export calibration that we don't run into in the states.

[Cringer]

Yeah that static knock table would be it.. It's ok to zero.

I've never seen that table populated with anything other than LT4 GEN 5's..

That is very bizzare but also seems like a export calibration that we don't run into in the states.

Chevy SS sedan (aka Holden Commodore) has values in the static table filled out on an E38.

[Alvin]

Chevy SS sedan (aka Holden Commodore) has values in the static table filled out on an E38.

Well I'll be damned.

I've never seen this as a result.