Cold Air and Knock

[NY87GN]

I recently installed my new cold air system, after some very aggressive driving I pressed recall on my scanmaster and noticed a 3.0 knock. Not sure if just bad gas or need to adjust fuel after CAI install. My blm's look about right at wot 120's.
Thank you in advance for your time and response.

 

[charlief1]

It's cooler out side and you just put a cold air kit on. That means the engine is getting more air and not more fuel. Time to adjust the mix some.

 

[earlbrown]

WOT should have been closer to 128. Might need to add a little bit of fuel up top due to the cooler air temps. (or verify you have fuel pressure up top. You do have a pump, hotwire, an good wiring, right?)

 

[NY87GN]

Earl, thanks for your feedback, yes hotwire and fuel pump, 60lbs injectors, matching chip etc... I will add some fuel. Not sure if this is a dumb question but,,,,, obviously zero knock is ideal, is there any level of "Safe" knock. I was told upto 6.0. I dont think thats right...
Agian many thansks..

 

[Bescurred]

Only "safe" knock is false knock...

 

[Emiliano Lago]

safe level is 0 knock,that's what you need to look for.Good luck on taking care of that

 

[Heisenberg]

Only "safe" knock is false knock...

Earl - wouldn't a Block Learn Multiplier of 120 (less than the optimum 128) mean the ECM was trying to trim injector pulse / fueling though?
Or maybe that is what you are saying - it needs to be opened up a smidge.
Didn't hear what kind of MAF was running.

 

[earlbrown]

Colder air would require more fuel. Depending on the chip it most likely locks on 128 at WOT.


Back in the old days it was common to trim that with fuel pressure adjustments. Modern chips (and/or Translators) make it easy to change WOT fueling.

 

[NY87GN]

Earl - wouldn't a Block Learn Multiplier of 120 (less than the optimum 128) mean the ECM was trying to trim injector pulse / fueling though?
Or maybe that is what you are saying - it needs to be opened up a smidge.
Didn't hear what kind of MAF was running.

Heisenberg, I am running the LT1 MAF with Translator, I am going to try and add more fuel this week and post.
I really appreciate everyones advice and insight. Very, very helpful.

 

[we4Mateo]

Who's chip do you run? TT chip won't change wot fuel with translator adjustments, you need an extender chip to make the translator work that way. If using a TT chip, you need to add fuel through the chip.

 

[NY87GN]

Who's chip do you run? TT chip won't change wot fuel with translator adjustments, you need an extender chip to make the translator work that way. If using a TT chip, you need to add fuel through the chip.

Yes, I run the extender chip, im going to try to make the adjustment on Translator.

 

[Wld87GN]

So here is a stupid question... but never having it pointed out to me, what does this "knock" sound like?

 

[Bescurred]

Marbles in the upper intake pinging around...

 

[PSID6]

Pinging, snapping, bucket of bolts, blown head gaskets, windowed blocks, aka carnage

 

[we4Mateo]

So here is a stupid question... but never having it pointed out to me, what does this "knock" sound like?

I think it sounds like someone hitting a desk in rapid succession with the eraser end of a pencil but without the eraser in the pencil. Just the metal tip hitting the desk.

And not a stupid question. Once you train your ear, you'll hear it in other cars too.

 

[Wld87GN]

ok, I have a tapping noise that does not sound like that. I just had my drivers side header welded up. Sorry don't mean to hi-jack the thread

 

[psycho6cyl]

Knocknsounds like a man wimpering and crying,wait thats the sound after you had to much knock lol. Sounds like marbles hitting everything in the motor...

 

[Wld87GN]

Okay, I think I understand the "knock" noise.

Can I safely assume that the reason the OP was asking with cold air intake is that the engine has now "leaned" and the knock is noise that is a result of lack of proper air/fuel ratio?

If this is true, how do you fix it? I cannot imagine that adjusting the FPR will fix this, but shit I have learned so much I cannot leave anything to chance.

 

[TurboBuRick]

In the more extreme form it sounds like gun shots under the hood.

What were o2 millivolts when you took the knock reading? What was MPH?

Rick

 

[we4Mateo]

Okay, I think I understand the "knock" noise.

Can I safely assume that the reason the OP was asking with cold air intake is that the engine has now "leaned" and the knock is noise that is a result of lack of proper air/fuel ratio?

If this is true, how do you fix it? I cannot imagine that adjusting the FPR will fix this, but shit I have learned so much I cannot leave anything to chance.

Upping the fuel pressure does work with the older chips if the motor is lean, but now a days you can add or subtract fuel via a translator or through the chip itself using a scanmaster.