43 knock counts at part throttle

[fwdtsi]

Hello, I am trying to figure out why I have 43 counts of knock just at part throttle. I will be just cruising under vaccum and go to hit the gas to pick up speed and it will knock crazy, but if I get on it from the start and keep my foot on the gas it wont knock. Its only when you let off the gas and just try to cruise. I have richened idle up on my maf translator +15% and it actually worked for a bit but then it just started to do it again and the funny thing is everytime I richen Idle up my fuel trim will go down from 139% to like 116% but if you let it idle for awhile it will start climbing up to 139% again. Can somebody help, thanks

 

[AL92]

You have what many of us have its called phantom knock.it seems to come and go ..
Some things that have worked for some but unfortunately not for all :

1)upgrade to newer 3 g style lifters easy drop in cost about 130 bucks.
2)change out knock sensor bit of pain install..about 60 bucks US
3)Put MCCC treatment thru engine and on pistons..cheap at your local dealership.
4)Bad motor mounts..not sure how much these cost..install easy to annoying depending on which ones are bad.
5)Some have some luck with going to disabled straight thru pcv catch can mod.Taboo site shows pics of this.
6) Some have found other sources of rattling under the hood..loose starter bolt etc.

Lilkly maft won't help.I have one also.But I haven't done any of the above either yet aside from putting thru one can of MCCC.I did buy new knock sensor not intstalled yet and will order new lifters shortly.
I tried to mod my factory pcv and drill it out but its not easy to drill out.LIkely will just get a straight thru fitting to replace it.Already not venting the engine into the intake tract.Supposedly that oil going into intact causes knock and carbon build up on pistons.

So mabye try some of the above.And let us know if that works.There is a entire message board that just talks about this knock problem.Some guys had luck with some of the above..some had none.

Good luck with yours..

 

[fwdtsi]

see, I dont think its phantom knock. Its real, my lifters dont even tick. I richened it up a whole lot on idle and part of it went away but sometimes when you hit the gas hard cruising it will do the same thing. I want to believe its a weird vaccum problem. Can you actually feel phantom knock pull back timing? becuase when it knocks like this and you hit the gas you can feel it pull timing back real bad

 

[TURFNNSURF]

To the ECU Phantom Knock and Real Knock are the same thing! Knock over 12 to 14 counts will pull timing. The knock sensor is sending a signal to the ECU telling it there is something wrong in the motor and to pull timing. I have a similar issue with my car but only intermittently. At part throttle, under NO BOOST, when I try to accelerate, lets say from 40mph to 45mph, i'll get 43 counts of knock. As soon as I let off the gas and then get back into it a little more the knock isn't there. Im hoping that a GM MAS and translator will help with metering air flow and maybe also lowering my base timing from 5 or 6 to 2 or 3 will keep part throttle knock down.

 

[AL92]

Phantom knock is actually not the best choice of words..its real,it shows up..just not the same knock you get from being too lean under boost.If you can richen up wot and cut down on knock or even richen up part throttle and reduce or eliminate it then thats not what they call phantom knock.This knock happens when not under boost and at times like you said and usually not even all the time.Thats what makes it hard to get rid off.It not cut and dried.It might be from lifters.it might be from carbon on your pistons.It might be from your old knock sensor ,it might be from your motormounts or something thats rattling under there or it might be as one poor guy found out trashed bearings or things in the engine.It might be a lot of things.
Some guys figure it out and fix it ,some don't.Mine seems to fortunately not be all the time.And yes big counts make the car slower for sure.
So this isn't a good thing.

One last ditch way to eliminate it might be to go to standalone like aem ems as it has some special knock options and think you can run the 2g sensor and set different amounts of sensitization.

I will post some results when I start doing some of the things I posted about.

One test is to run race gas or maybe like 30% xylene or toluene.If the knock goes away its octane related.You can also try reducing boost to as low as you can go.

But if its there off boost then likely again its what is called phantom knock.Its got to be physically there in terms of some real noise setting off the knock sensor but finding out exactly what is doing it can be a pain.

 

[fwdtsi]

This was very awful before until I made it run pig rich at idle. Now its not as bad, But if I drive for 15 min. It will knock like this at least 4 times out of my drive so a daily driving is screwed. Can I wrap something around the knock sensor, maybe to dampen it out? What are some fixes that are not expensive? thanks

 

[Enigma_Man]

Here's the easy way to see if the knock is "Actual" (gas is exploding, not burning nicely) or "phantom" (other misc. noise).

Find somewhere that sells really high octane gas, not just 93 or anything like that. Get at least 100. Put as much of that as you can afford into as empty a tank as you can get.

If your knock goes away, then it is "actual" knock, if it doesn't (which it probably won't) try one of the other things AL92 listed, which is a very good list of things to do.

-Jesse

 

[GSX JOE]

What if the knock goes away completely when you put in race gas? What would you check then?