Low load Knock retard

[tlavoie87]

any ideas.. im getting quite a bit of low load Knock (under 3000) only on cylinder 4.. my fueling is really good under 3% stfts ..not sure if this is coincidence but it started when i put my new catch can in.. should i replace the sensor ?.. i tried pulling spark with no change.. any ideas? thanks

[Leo72793]

Originally Posted by tlavoie87

any ideas.. im getting quite a bit of low load Knock (under 3000) only on cylinder 4.. my fueling is really good under 3% stfts ..not sure if this is coincidence but it started when i put my new catch can in.. should i replace the sensor ?.. i tried pulling spark with no change.. any ideas? thanks

The v6 is notorious for internal top end build up. depending on your mileage damage is probably already been done. You may need a top end cleaning ( valves as they arent hit by fuel to clean them )

[tlavoie87]

..i spray a ton of meth so my valves are very clean..already checked that ..thanks for the input

[tlavoie87]

Originally Posted by Leo72793

The v6 is notorious for internal top end build up. depending on your mileage damage is probably already been done. You may need a top end cleaning ( valves as they arent hit by fuel to clean them )

so come to find out my valves were not as clean as i thought .. just to play it safe i decided to take my manifold off again to double check.. and they were all gunked up so i went to harbor freight and made my own walnut blaster for under 60$$ and worked amazing.. looks brand new.. ill do a log later to see if it helps with the KR

[Leo72793]

Originally Posted by tlavoie87

so come to find out my valves were not as clean as i thought .. just to play it safe i decided to take my manifold off again to double check.. and they were all gunked up so i went to harbor freight and made my own walnut blaster for under 60$$ and worked amazing.. looks brand new.. ill do a log later to see if it helps with the KR

lol nice. post a DIY for that?

[Lil' Nasty]

Originally Posted by Leo72793

lol nice. post a DIY for that?

+1 I'm hesitant to try this as I'd be worried that the valve isn't all the way seated.

[Russell James]

What kind of oil are you using? Oil burning can induce knock. Especially if using a high detergent oil. Many of the mass marketed oils have switched to calcium as a detergent.... which turns out to be a possible cause of LSPI... low speed knock.

Burning oil, especially an oil with calcium can cause that low engine speed/high load knock. It basically mimics a diesel engine.... high cyl pressure, some oil in the fuel... same recipe for diesel combustion.

May have nothing to do with it, but maybe try some low detergent racing oil as an experiment to see if the knock reduces.

https://fuelsandlubes.com/fli-articl...ewest-engines/

[tlavoie87]

Originally Posted by Russell James

What kind of oil are you using? Oil burning can induce knock. Especially if using a high detergent oil. Many of the mass marketed oils have switched to calcium as a detergent.... which turns out to be a possible cause of LSPI... low speed knock.

Burning oil, especially an oil with calcium can cause that low engine speed/high load knock. It basically mimics a diesel engine.... high cyl pressure, some oil in the fuel... same recipe for diesel combustion.

May have nothing to do with it, but maybe try some low detergent racing oil as an experiment to see if the knock reduces.

https://fuelsandlubes.com/fli-articl...ewest-engines/

Rotella T6

[Russell James]

Originally Posted by tlavoie87

Rotella T6

I'd try a performance gas engine oil.

In the list of possible culprits for LSPI, oil additives/detergents is one of them. Easy to rule out by trying a low detergent racing oil and seeing if KR is gone.

Diesel oils are loaded with detergents to combat soot. And they are not formulated to run in a gas engine, so the oil engineers spec'ing out the formula could care less about LSPI.

I'd at least try it to rule it out before chasing down other causes.

[tlavoie87]

Originally Posted by Russell James

I'd try a performance gas engine oil.

In the list of possible culprits for LSPI, oil additives/detergents is one of them. Easy to rule out by trying a low detergent racing oil and seeing if KR is gone.

Diesel oils are loaded with detergents to combat soot. And they are not formulated to run in a gas engine, so the oil engineers spec'ing out the formula could care less about LSPI.

I'd at least try it to rule it out before chasing down other causes.

thanks for the info..theres a few of us FI guys running the Rotella due to the heat.. what do you recommend for a Good Performance oil i try and run a 5w40 full syn

[Russell James]

Originally Posted by tlavoie87

thanks for the info..theres a few of us FI guys running the Rotella due to the heat.. what do you recommend for a Good Performance oil i try and run a 5w40 full syn

Amsoil ZRod 10w30. Or Amsoil Signature Series 10w30. The ZRod I believe has more zinc/phos, which in theory could be damaging to cats and O2s. But I think that is just a theory. I've never actually seen anyone having problems.

I run the Signature Series 10w30 in my LS3 1LE. Lots of track days, and no complaints, I think its a real good oil. I have a drag car that I run Brad Penn racing oil... top quality stuff. But it's only partial synthetic. If there are heat issues, I'd probably stick with a full synthetic.... Amsoil, Redline, Driven.

I talked with one oil chemist at Brad Penn about using high zinc/phos racing oil in cars with cats and O2s. He said, technically they can't recommend it because it's possible over a very long period... if an engine is burning a lot of oil... it could reduce the cat efficiency and reduce O2 life span. But he also commented, it's more a theory and practically if an engine isn't burning much oil, shouldn't be an issue. And if that engine has performance mods... real good to have the extra wear protection of zinc/phos.

In my drag car I tried all kinds of oils over the years. They all seem to have issues, and the biggest thing was all the big name oil companies seem to change their formulas every year. One oil that worked fine one year, was killing my bearings the next. Or causing detonation. A friend turned me on to Brad Penn, started running Brad Penn straight 40 racing green oil. Perfection. My bearings now last 2 years, no more cam wear, no more detonation. And I know in talking to the chemists they have no intention of ever changing the formula.

The Amsoil Zrod and Signature Series I'm pretty sure are the same formula that has worked great for a long time. So I know those are a great choice for a performance street car.

[tlavoie87]

cool thanks