01MAROONz2890

Hey guys I recently swapped in an ls2 on my project car that used to have an ls1 in it. The knock sensors are now on the sides of the block. I have HEARD people change the sensitivity on the sensors but most people in practice seem to leave the tables stock. The guy tuning the car locally here in ohio said it should be just fine with the stock tables. I'm just looking at what people are actually running.

JimMueller

iTrader: (9)

Not sure if this is apples-to-apples, but when I switched from a LS1 to a LS3, using the OEM computer, I left the knock sensor tables at OEM defaults, using the LS1 knock sensor PN's.

redbird555

iTrader: (14)

I'm actually in the same boat lol thanks for the reply here jim I sent you a pm about this but the post answered my question. I find a lot of people talk about it but most don't actually do anything.

Anyone else?

DrX

iTrader: (6)

I had to modify my tables to get any knock to show up. Changed from cylinder mode to engine mode and increased sensitivity.

redbird555

iTrader: (14)

See i experimented with mine, I left it in cylinder mode and reduced the table by 30% which gave me false knock. I then cut it down to 15% from stock and that seemed like a good spot. However I cant do any wot pulls in 4th. I did 3-4 in 2nd and 3rd gear and they were clean but is that safe to say that they wont pull for false knock again at some point when I'm not logging it.

Basically I'm afraid of making them too sensitive and having them pull timing when its not needed.

JimMueller

iTrader: (9)

Perhaps it's PCM related? My VCM OS is 9375576, which is a 1998 OS... I have read that some sensors are incompatible with certain PCMs.

http://www.hptuners.com/forum/showth...ensor+resonant

I just compared my current calibration to the stock one the dealer put in when they replaced my PCM a few years ago, the knock sensor tab is completely stock. I used ACDelco PN 2133521 knock sensors, but the local engine builder tapped the holes on the side of the block.

thunderstruck507

iTrader: (18)

I ran mine stock and then have been gradually increasing the sensitivity...took a good bit to get anything to show up.

Not sure I trust them.

If you don't increase the sensitivity I would make sure to be extra picky about fuel. Top tier name brand premium only (nothing from walmart, ez mart, caseys, kum n go, etc)

DrX

iTrader: (6)

Should have included that I am still using the LS1 style sensors, screwed into pre-tapped holes on the sides of the LSX block(iron). Might make a difference iron vs aluminum.

redbird555

iTrader: (14)

i would assume it does but out of curiosity how much did you decrease your tables by from stock

DrX

iTrader: (6)

I just implemented engine mode, including filling in the related multiplier A and multiplier B tables, which were zeroed in the stock tune. Don't recall where I got those values from or how much I modified them. The stock cylinder mode tables are untouched/unused.

I see reasonably normal knock sensor activity.

redbird555

iTrader: (14)

Heres what I have found thus far and I feel like I'm close. I tried switching to engine mode and that just resulted in false knock in a lot of random places. The global setting tables I believe are used when you have that mode active seeing as changing that table netted me no different in knock sensor activity. In the other table I had tried upping sensitivity 15% at first and that still didnt show any activity. Then I tried 30 and got one degree 1 time out of 3-4 pulls. I then upped it to 35 and saw knock retard in the 4500 rpm area which should be false as higher up in the rpm range I have more timing and had nothing.

So I will try one more iteration of 25% since 30 showed a little and 35% showed too much. I'm thinking 15-25% should be a good spot. What say all of you lol?

DrX

iTrader: (6)

These are my engine mode tables:

redbird555

iTrader: (14)

are you using efi live drx?

In hp tuners the first table you have is rpm vs cyl the second one is global gain. I changed global gain once and didnt get any response so I just changed the rpm vs cyl which is what ED hutchings does. That's where I originally got the 30% figure.

I just went out and tried 25% and got no knock retard like the other sporadic readings so I'll do a couple more logs and if it looks good I think I'll keep it there. Besides if the tune is good the knock sensors really shouldnt have to be used unless you get bad gas

redbird555

iTrader: (14)

I did a couple other more logs and 25 seems to be the number. What's interesting is a I did a low rpm pull and found that I got a little 1-2 degrees KR around 2800 rpm however those tables were stock... I only modified the 3600 rpm on up tables. So now the question is should I put the others back to stock since I know they work with stock low rpm tables

DrX

iTrader: (6)

Yes, EFILive. Don't see those tables in HPT. I can select the knock detection mode, but don't have any tables to populate. Seems that the knock thresholds would all be 0V(maximum sensitivity = knock retard always active) if all the table values were left at 0 as per my stock tune.

redbird555

iTrader: (14)

I attached what the tables look like in my bone stock tune. I modified both but had no results from the map one so I toyed with the rpm vs cylinder.