what is considered an allowable amount of knock?

[excel8951]

I've been playing around with DSMlink for a about a week, trying to figure it out thus I've also been doing a lot of data logging.

What is considered an allowable or normal amount of knock? whats considered A LOT of knock?

on a few occasions I've seen some instances of maybe 2 or 3 degrees but on one occasion a spike of 13 degrees and @ 4500 RPM- i know thats not good.

also, anybody have some recommendations on getting to know ECM link. I've watched all the demos and browsed the wiki but its all pretty sporadic and theres a lot that isn't covered.

 

[LiquidX]

Generally you want 0* timing pull. I'd say that no more than 3* would be "alright". You should tune for 0* however.

 

[JusMX141]

on a few occasions I've seen some instances of maybe 2 or 3 degrees but on one occasion a spike of 13 degrees and @ 4500 RPM.

Holy shit man....that just murders your timing curve. If you had 13* of advance, it would now be 0* at 4500rpms.

I'd suspect a bad knock sensor or something else creating sound within the engine that is translating to knock at that RPM (timing belt idler pulley, bad water pump, etc).

 

[excel8951]

the motor was just completely rebuilt about 2 years and 5k miles ago. I don't doubt that its possible that one of those components could be going bad and getting translated into knock but I find it unlikely. again, that 13 degree timing retard only happened once and was very short.

something else that makes this more interesting, the car has a 3" GM MAF with MAFT and Delphi 680CC injectors.

according to the ECMlink wiki the normal global fuel settings at 37 PSI fuel pressure (which my car is set at) is -29% and 300 micro seconds of dead time.

I had to set mine at -50% and 1050 micro seconds of dead time for the car to run right. what could cause such a variance?

I ordered cable from ECMlink to directly wire the MAF into the computer and eliminate the MAFT so I'll see if it makes a difference but still. what could do that?

 

[Artago]

Do you get 2-3 degrees of knock or counts of knock?

 

[excel8951]

2 to 3 degrees of knock retard and one instance of a 13 degree knock retard for a period of .19 seconds.

I wasn't aware there was a way to monitor the actual counts of knock in ECMlink.

I understand that knock retard is the ECU backing timing down to compensate for knock. what exactly is a "count of knock"? I mean, a detectable amount of knock over what period of time?

 

[LiquidX]

Once the sensor picks up an audible sound in a set frequency/range then it will count it as knock. I cant recall what it amounts to but I want to say that 6 counts of "knock" is 1* of timing pull. Don't quote me on that however.

Regardless, you'll be better off tuning for 0* timing pull rather than having the ECU pull it through some possibly bad sounds. It's best to make sure it's real knock and not just phantom knock.

 

[excel8951]

whats the best way to rule out Phantom knock? I mean I could just start replacing parts and see what happens but thats not really practical. is there somewhere to start?

also, when tuning, how do you know when to pull/add fuel versus pulling/adding timing? Obviously if your AFR is whacked you want to adjust your fuel to compensate but does the fuel calculation still play a role in eliminating knock?

 

[LiquidX]

Well first you would want to see if anything is vibrating under the hood. Loose parts, wires, metal on metal contact etc. Next you could throw in either race gas and see if it goes away or you are able to get setup for e85 run that. I would say race gas though being that you are fresh to tuning and all.

First you need to determine what AFR you want to run. Using your wideband (hopefully logged) do a pull and see where the discrepency is between estimated AFR and your wideband. Adjust accordingly with either the sliders or using the DA table (more accurate). Go do another pull and see how things line up again.

If you see knock get off the throttle. Lower the point where it knocks down x* (same as the timing pull) and generally a * or 2 before it starts to knock.

If you are too rich or too lean you will also knock. It's a lot of trial and error for the beginner and even some of the experienced members. Once you do it enough you'll understand and learn it a lot better.

Just take small steps and you'll be fine.

 

[Artago]

2 to 3 degrees of knock retard and one instance of a 13 degree knock retard for a period of .19 seconds.

I wasn't aware there was a way to monitor the actual counts of knock in ECMlink.

I understand that knock retard is the ECU backing timing down to compensate for knock. what exactly is a "count of knock"? I mean, a detectable amount of knock over what period of time?

Yeah you can log raw knock. Ideally you want to stay below 1* (ie: 0.7 = 0) in WOT pulls.

I want to say that 6 counts of "knock" is 1* of timing pull.

I think it's 3 counts = 1* but don't quote me on that see: www.ecmlink.com

Well first you would want to see if anything is vibrating under the hood. Loose parts, wires, metal on metal contact etc.

I have some of this knock happening when pulling out from a stop. My heat shield is vibrating.

 

[Jaydog]

I've gotten .4 - .7 knock the last two times that I was tuning. It happened at 3500-4500rpm.

 

[excel8951]

did a pretty thorough check and after talking with a guy that knows about these cars and reveiwing data logs, the thinking is it phantom knock maybe from my exhaust rattling

 

[Artago]

I've gotten .4 - .7 knock the last two times that I was tuning. It happened at 3500-4500rpm.

I get that too. Not a big deal. Are you going WOT during this time?

did a pretty thorough check and after talking with a guy that knows about these cars and reveiwing data logs, the thinking is it phantom knock maybe from my exhaust rattling

I have that that too but not from the exhaust.

 

[MitsGray97]

Would like to revive this thread. Now I know that you always want to tune to 0° knock ret. So my issue is that i got knock anywhere from .7° to 3° knock ret. I have pulled timing and added fuel and i still cant get it to go away. Now the issue only persists at part throttle from about 2500-3k. Ive performed some pulls at full boost wot. And i dont see very much knock at all (very little knock). But at part throttle it knocks all the time... litterally. I get lots of constant knock. It hasnt gone over 3° but it does hold for seconds. Any ideas on what i could do to get rid of it? Id really appreciate any help i could get. Thanks.

 

[c2ypt1c]

Could be phantom knock. What are your knock sensor settings at?

 

[red_devil]

A log would help

 

[MitsGray97]

Sorry for taking forever, my laptop died on me so I couldnt log anything for a while, but it seems to have gotten worse. could anyone tell me how to post logs so you guys could see how horrible it is. thanks.

 

[RIDSM]

im trying to tune my 2g gsx and i keep getting .4degrees of knock im not going wot and temps are low so im not sure whats up im new to link so any info would be helpful ill post a log i get 2 instances of knock at around the 873 mark

 

[boost97gst]

.4 just isnt really knock. Its too small. Maybe pull a degree of timing or add a bit of fuel and see what happens.

 

[RIDSM]

i feel like my car probably needs a few degrees of timing pulled along with a few other things because its rediculously rich but i dont have enough knowledge to where i would know whats safe and what isnt

 

[snowborder714]

Make sure to read the sticky threads in here, and then once you've done that, start a new thread with your question and log(s).

 

[RIDSM]

ive read a few of them along with the ecmlink tutorials and my values still come out screwy. im not 100% sure whats wrong im going to put a new timing belt and water pump in along with new pullies because god knows when they were done last...and at risk of sounding like a noob i cant figure out how to start my own thread for the life of me

 

[born2tune]

So all my motor mounts are solid, and my subframe bushings in the front are solid, and im in the middle of my build and I wonder if I would deal with a lot of phantom knock when the time comes?

 

[jeremy1375]

So all my motor mounts are solid, and my subframe bushings in the front are solid, and im in the middle of my build and I wonder if I would deal with a lot of phantom knock when the time comes?

I am in the same boat and wondering the same thing.