Knock 136!?

[dano4127]

Hey guys,

Just wondering if you can give me an idea of what might be happening with my car

94 GTS25T Mods: Exhaust, Cooler, Pod and Power FC only use BP Ultimate and Royal Purple Oil

thursday night i had an intercooler pipe pop off and the car stalled was a little hard to start but once going again all seemed fine.

I did an oil and filter change on friday night also put on new silicone hoses for IC pipe

i feel as though since saturday night the car was running a little rough then lastnight late (was quite cold night)

i was heading home and the engine light was came on at 4500rpm the knock reached 136 so i babied it home

let it cool down for an hour while i stood there looking at the engine like a fool took it fo another short drive and the same thing happened

I did to put a bottle of Nulon Injector cleaner in my tank on saturday not sure if this could have anything to do with it though?

on the way to work today i did take it really easy but got the revs upto about 5500 twice which saw knock reach 35

so yeh any ideas on what the reason for the knock getting so high? Is it safe to drive it like this?

I think the car has not been tuned for atleas 15,000ks mabye even 20,000k could this be the reason - do cars just get out of tune??? or is this likely to be something more mechanical like a broken/melted/worn part?

cheers,

Dan

Edited September 11, 2006 by dano4127

[mad082]

if it was a cold night then that would've been part of the problem.

[dano4127]

ohh ok fair enough i thought that it was the other way around?

so cold = more knock?

[paulr33]

read the powerfc faq (in my sig), it covers knocking and debugging it in detail

[mad082]

yes, cold = more knock. cold air is denser, so it leans it out more.

[dano4127]

paulr33 - i just read that whole article awesome work now i feel like i need to go lay down to take all that information in!

i think i will take it to someone to get it tuned as i would like to put in a Z32 AFM, new fuel pump and mabye an AVCR then i can get it all setup at the one time and get the car fully retuned

you just seem to hear so many varied opinions on who to get to tune you car it is so hard to know who to trust!!!

[SKiTLz]

Cold = more knock? I thought knocking was a heat issue in the first place since its basically early combustion? Have i been looking at it backwards the whole time?

[The Mafia]

Cold = more knock? I thought knocking was a heat issue in the first place since its basically early combustion? Have i been looking at it backwards the whole time?

its both.

Cold air = More air = leaner more unstable mixtures = Knock.

Heat soak or hot air = hot fuel = unstable mix = knock.

you need to get it somewhere in between, or tune the car on a stinking hot day, and you'll never knock out in the cold.

Thats how I tune my car.

Also, cold air can make your turbo boost an extra psi sometimes, and lean the car out, causing knock. Get an electronic boost controller.

[SKiTLz]

Makes sense. Cheers mate..