Seeing knock sometimes in the 4,000-5,000 range.
05-10-2014, 03:35 PM
#1
Seeing knock sometimes in the 4,000-5,000 range. SOMETIMES.... is the key word. It's not consistent.
I first saw about 0.5-1.0 degrees of knock when the car was on the dyno back in November in the 4-5k rpm range. So to test if it was real, I dropped the timing in that area from 16 degrees down to 13, and still see the intermittent 0.5-1.0 degree of knock, so I don't believe it's real. I run 93 octane, and have tried a couple different places, and I'm spraying plenty of meth, enough to drop the afr's from 11.8 down to 10.5, so it's not lean.
As it's not related to timing, nor octane, I think it's just a phantom knock because like I said, it's not consistent. I could be at different throttle position, different rpms, different timing, and still get it.
So should I desensitize the knock sensors in this area?
Here's the log showing what I'm talking about. Sorry, didn't click in the right area, but it was a max of 0.7 degrees KR, and you can see it's only at 15 degrees of timing, and the afr was high 10s. I've dropped the timing in this area from 16 down to 13, and still see it.
Thoughts?
I first saw about 0.5-1.0 degrees of knock when the car was on the dyno back in November in the 4-5k rpm range. So to test if it was real, I dropped the timing in that area from 16 degrees down to 13, and still see the intermittent 0.5-1.0 degree of knock, so I don't believe it's real. I run 93 octane, and have tried a couple different places, and I'm spraying plenty of meth, enough to drop the afr's from 11.8 down to 10.5, so it's not lean.
As it's not related to timing, nor octane, I think it's just a phantom knock because like I said, it's not consistent. I could be at different throttle position, different rpms, different timing, and still get it.
So should I desensitize the knock sensors in this area?
Here's the log showing what I'm talking about. Sorry, didn't click in the right area, but it was a max of 0.7 degrees KR, and you can see it's only at 15 degrees of timing, and the afr was high 10s. I've dropped the timing in this area from 16 down to 13, and still see it.
Thoughts?
05-10-2014, 04:37 PM
#2
9 Second Club
It's just noise, if in doubt check with det cans, stethoscope, or whatever you want to call them.
But factory knock sensors are good for factory engines....modify anything that can affect how noisy they are, and any settings relating to the sensors will need checked and possibly altered to suit the new "noisy" engine
But factory knock sensors are good for factory engines....modify anything that can affect how noisy they are, and any settings relating to the sensors will need checked and possibly altered to suit the new "noisy" engine
05-11-2014, 07:45 AM
#3
Have you tried going the other way with the timing and see what happens? If its real, and you add more timing, you should see more knock right?? I have seen knock show up from being too rich and too little timing. With your meth you said you were in the 10's A/F wise, so add a degree or 2 and see what the log shows.
05-11-2014, 03:26 PM
#4
9 Second Club
Take randomly adding timing to an engine where detonation may be already present ( even though it isnt present in this instance ) as very bad advice. And I have never seen an engine with knock caused by too rich or low timing...even with AFR's dipping into the 8's
Keep it simple.
Pull some timing or just listen to the thing and confirm beyond any doubt..
Keep it simple.
Pull some timing or just listen to the thing and confirm beyond any doubt..
05-11-2014, 03:32 PM
#5
I've seen rich knock...but it was really just too much EGT and Rich fuel igniting itself...
likely just some noise...you will have to check with other methods to find out for sure if its real knock or not...
it could also be calculated knock... Burst knock....
burst knock is most likely what you are seeing....calculated from airflow/cylinder air values
remove burst knock stuff and see if it goes away
likely just some noise...you will have to check with other methods to find out for sure if its real knock or not...
it could also be calculated knock... Burst knock....
burst knock is most likely what you are seeing....calculated from airflow/cylinder air values
remove burst knock stuff and see if it goes away
05-11-2014, 03:36 PM
#6
Take randomly adding timing to an engine where detonation may be already present ( even though it isnt present in this instance ) as very bad advice. And I have never seen an engine with knock caused by too rich or low timing...even with AFR's dipping into the 8's
Keep it simple.
Pull some timing or just listen to the thing and confirm beyond any doubt..
Keep it simple.
Pull some timing or just listen to the thing and confirm beyond any doubt..
, I have proven it on back to back logs that too rich a/f and too little timing WILL knock. Just because you haven't seen it doesn't mean it doesn't happen as guys over on efilive have seen the same. Also, I never said to RANDOMLY add timing. The knock on that log is hardly much to be worried about considering what his a/f and timing looks like and he's spraying meth. Adding a degree between pulls if the first log looks like the above will prove if its real or not, and nobody is saying to go make a mile run with the extra timing.
05-11-2014, 03:49 PM
#7
While I appreciate the condescension , I have proven it on back to back logs that too rich a/f and too little timing WILL knock. Just because you haven't seen it doesn't mean it doesn't happen as guys over on efilive have seen the same. Also, I never said to RANDOMLY add timing. The knock on that log is hardly much to be worried about considering what his a/f and timing looks like and he's spraying meth. Adding a degree between pulls if the first log looks like the above will prove if its real or not, and nobody is saying to go make a mile run with the extra timing.
, I have proven it on back to back logs that too rich a/f and too little timing WILL knock. Just because you haven't seen it doesn't mean it doesn't happen as guys over on efilive have seen the same. Also, I never said to RANDOMLY add timing. The knock on that log is hardly much to be worried about considering what his a/f and timing looks like and he's spraying meth. Adding a degree between pulls if the first log looks like the above will prove if its real or not, and nobody is saying to go make a mile run with the extra timing.while you are technically correct... that adding 1* when you are pretty sure its not actual knock should not be an issue.....
it is bad tuning advice to tell somebody to add timing when they are seeing knock in the scanner.
you should always exhaust other options before trying to add timing to prove if its knock or not..
and in some cases...1* more can be the difference between a working engine or a busted piston...
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05-11-2014, 05:21 PM
#8
while you are technically correct... that adding 1* when you are pretty sure its not actual knock should not be an issue.....
it is bad tuning advice to tell somebody to add timing when they are seeing knock in the scanner.
you should always exhaust other options before trying to add timing to prove if its knock or not..
and in some cases...1* more can be the difference between a working engine or a busted piston...
it is bad tuning advice to tell somebody to add timing when they are seeing knock in the scanner.
you should always exhaust other options before trying to add timing to prove if its knock or not..
and in some cases...1* more can be the difference between a working engine or a busted piston...
What you guys aren't realizing is he posted asking about changing the knock sensitivity tables, meaning they're likely stock. If they are the recovery time is super slow so once the initial knock event is detected, the decay rate takes forever. If he adds a degree, the tune will simply retard more timing and it'll still take forever to decay, keeping the motor safe. Maybe I'm just more immune to dealing with knock stuff since I have 2- 98 computer fbodys
05-11-2014, 06:22 PM
#9
Trust me guys, I know better than to add timing when seeing knock. Re-read what I have already done in trying to diagnose if it was real or not. I pulled out 2 degrees of timing, and still saw the random 0.5-1.0 degree. Tried gas at different locations, to eliminate bad gas, and still saw it.
I'm also calling it random because it's not everytime I hit specific rpm, or map position that I get it. Sometimes I do, sometimes I don't.
I'm also calling it random because it's not everytime I hit specific rpm, or map position that I get it. Sometimes I do, sometimes I don't.
05-11-2014, 06:28 PM
#10
Trust me guys, I know better than to add timing when seeing knock. Re-read what I have already done in trying to diagnose if it was real or not. I pulled out 2 degrees of timing, and still saw the random 0.5-1.0 degree. Tried gas at different locations, to eliminate bad gas, and still saw it.
I'm also calling it random because it's not everytime I hit specific rpm, or map position that I get it. Sometimes I do, sometimes I don't.
I'm also calling it random because it's not everytime I hit specific rpm, or map position that I get it. Sometimes I do, sometimes I don't.
05-11-2014, 06:29 PM
#11
Knowing Alchemist, he usually is rather thorough with his setup and wouldn't ask the question if it was something obvious and he hadn't already played with it. We're also not talking about a stock motor. Doing lower gear pulls and playing with timing and watching the logs is how you find out what the car likes.
What you guys aren't realizing is he posted asking about changing the knock sensitivity tables, meaning they're likely stock. If they are the recovery time is super slow so once the initial knock event is detected, the decay rate takes forever. If he adds a degree, the tune will simply retard more timing and it'll still take forever to decay, keeping the motor safe. Maybe I'm just more immune to dealing with knock stuff since I have 2- 98 computer fbodys
What you guys aren't realizing is he posted asking about changing the knock sensitivity tables, meaning they're likely stock. If they are the recovery time is super slow so once the initial knock event is detected, the decay rate takes forever. If he adds a degree, the tune will simply retard more timing and it'll still take forever to decay, keeping the motor safe. Maybe I'm just more immune to dealing with knock stuff since I have 2- 98 computer fbodys
I haven't touched the actual knock sensors tables, other than making the decay happen quicker, but even there I was very conservative with how quickly the decay happens. You are right, I was looking for advice on which table to modify, and what a safe change would be.
As for the comment of burst knock, I don't think it is, because people have said that burst knock doesn't get logged as regular knock, but rather there is a specific value to measure it.
05-11-2014, 06:31 PM
#14
TECH Enthusiast
Also wondering if it's in a certain gear? Lately but not all the time, I've been feeling some flat spots in upper rpm range in just 3 or 4. I was thinking I had a knock issue too.
05-11-2014, 06:37 PM
#16
Just checked, and my burst knock table is zeroed already.... guess I did that a while ago when I first went procharger....so it's not burst knock.
I'm wondering if it's wheel spin causing a vibration issue, or maybe I have a harmonic issue somewhere in the driveline.
I'm wondering if it's wheel spin causing a vibration issue, or maybe I have a harmonic issue somewhere in the driveline.
Last edited by The Alchemist; 05-11-2014 at 06:47 PM.
05-12-2014, 06:28 AM
#17
It's possible its something in the drivetrain....I know my TA will pickup knock in 3rd, but as soon as I hit 4th, it goes away. Doesn't matter if I vary fuel from the 10's to upper 11's and have anywhere from 8* to 14* of timing. You didnt say if it was gear dependent or not, I am assuming you were in 4th if your speed in the log was correct. Do you see it in 3rd?
05-12-2014, 07:37 AM
#19
It's possible its something in the drivetrain....I know my TA will pickup knock in 3rd, but as soon as I hit 4th, it goes away. Doesn't matter if I vary fuel from the 10's to upper 11's and have anywhere from 8* to 14* of timing. You didnt say if it was gear dependent or not, I am assuming you were in 4th if your speed in the log was correct. Do you see it in 3rd?
Maybe. I do have the solid timing chain damper, but that doesn't mean it's not making some noise.
05-12-2014, 09:57 AM
#20
With the solid motor mounts my LS KS’s are useless. I did work with knock sensors for years back in my my turbo buick days, and more recently with my DSM. I found true knock isn’t intermittent/sporadic. True knock will almost always start low and build. Blips of 1* or less for a brief period I always ignored. True knock in my case would always start out small and if you stayed in the throttle it would build with intensity. IE I’d see 1* at 5k and it would progressively get worse say 5-6* by 5600 or so.
I’d never suggest someone completely ignore knock readings. If your plugs look good and you see a random 1* or less blip I wouldn’t worry about it personally.
Good luck!
I’d never suggest someone completely ignore knock readings. If your plugs look good and you see a random 1* or less blip I wouldn’t worry about it personally.
Good luck!
