tuning out knock, the checklist

[v8s_are_slow]

okay, i'm seeing a lotta guys here comparing their trims and knock. i have the same problem at the moment. i'm around 100 in low, mid, and wot trims yet i get anywhere up to 28-30 something counts of knock.

anyway, i wanna know EVERYTHING that i could do to get rid of knock and what all would cause it. would think i need to have the air cool enough (have a dejontool race front mount), think i'd need to have big enough injectors and pump (running 650's and 255lph walbro pump with GT-13 pump), would think you'd need good plugs (have ngk's bpr7's but just have to throw them in) but not sure how much, if any, that gap would have an effect on it, and maybe if the motor was running a bit hotter that would have a part in it??? have a fluidyne radiator sitting in front of me but have to throw that in as well. bad knock sensor maybe as well?

of course tuning is an obvious answer but just wanna make sure i'm ruling out anything that could be a problem and maybe a checklist for anyone who's having the same problems, they'd know of everything to go and look at being the problem. and i have the newer version maft just so ya'll know. i wanna throw in the radiator and new plugs to see if it helps any, but just looking at everything in the meantime aside from tuning it good. anyway, thanks for the replies guys!!!

scott

 

[TurboGeoff]

If your tuning isnt terrible, its probably phantom knock.

 

[v8s_are_slow]

well, it's only doing it at WOT. no part throttle knock at all. my coolant temps are around 204-209 on the highway right now (still warm here in florida) so of course the reason for the fluidyne. egt's are at about 1250 or so at about 65-70 mph. think that's normal. think my tuning is okay so wanting to rule out all options before i go messing around with my maft again.

 

[scottsee]

noisy lifters in normally 80% of phantom knock.

 

[R3dR]

what do your plugs look like after you run the car for 20 min or so at 70?

I am not talking about boosting it or anything like that.

I like to have the egt closer to 1350 or so at 70 mph with 3500 or so rpm.

Just giving you some suggestions.

 

[Joesmoke]

The way I see it, if your engine is healthy (good head, compresion, yada), you feed it cool air (you have a big front mount) enough fuel (you have 650's, assumed they are adjusted right ) and give it good gas, there is not a hope in hell that you could be having true detonation/preignition in the high 20's, mid 30's. Period. Not going to happen.

Also, when watching for knock, if the sum peeks and then goes away almost instantly as soon as you stop giving it gas, it is usually engine noise. True knock will peek, then step down slower.

Also, detonation/preignition is less likely to occur at high load. More likely to occur at low rpm and light load.

EDIT FOR REASONING ABOVE:
Why? because det has a window where it will be more likely to occur. Between 10 deg and 70 deg ATDC. This window is approx 20ms @ 500 rpm's and only 1.25 ms @ 8000 rpm. There is not nearly as much time in the combustion process for it to happen. Not saying it cant or wont though.....
Source for the above information @

http://ccrc.wustl.edu/~roger/427M/spra039.pdf

Yes, I did just regurgitate the information, but it does make sense.
As always, if someone sees a flaw above, speak up.

 

[psychlow]

Also, detonation/preignition is less likely to occur at high load. More likely to occur at low rpm and light load.

Huh?

This doesn't make sense to me, as with a higher load, you're normally going to have more stress on the engine, more heat and higher combustion pressures at peak torque.

V8s_Are_Slow, I notice that you're using a MAFT to tune.... You may be seeing too much timing advance due to the decreased airflow that the ECU is seeing. At WOT, because of the engine load and amount of advance, it may be knocking.

Checked your base tming lately? If it's at 5*, try backing it down 2-3*.

 

[v8s_are_slow]

haven't checked the plugs lately. but i'll have to do it here soon. not sure how accurate this would be since i don't know my exact base timing. but i just did a log week before last and haven't driven the car since. did a 3rd gear run starting at 3063 rpm and ran it to 7031 rpm.

i'm trying to figure out how to copy and paste the info from the pl viewer from pocketlogger. but i'll give a brief overview real quick.

fuel trim low 105
fuel trim mid 108
fuel trim high 97
coolant 200

and here's a lil chart for some of the info. guess i'll just have to type out each reading. from left to right....rpm, knock, timing, and O2's. only listing from 5531 rpm and up cause that's where the knock starts (not to mention it's way more than i wanna type).

5531, 0, 29, .86
5531, 3, 29, .86
5844, 6, 29, .86
5969, 13, 26, .86
6000, 12, 27, .86
6094, 12, 27, .86
6563, 23, 25, .86
6719, 22, 25, .86
6813, 22, 26, .86
7031, 21, 27, .86
7031, 28, 25, .71

the pl viewer cut off the end of the log for some reason but on my palm, after i let off the gas, it shot down to 6312 rpm and knock went to 1 and then the 5500 and 0 again. so it went away pretty quick.

at the moment i have some bosch plugs in there that are pretty dang new. think they're regulars but i have the bpr7's ready to go in when i get the chance (dang broken foot and surgery. uggghhhh!!!!). anyway, ya'll tell me whatcha think. laters!

scott

p.s. i made a typo earlier. i'm not running 1250 at 65-70 mph on egt's. it's about 1300-1350.

 

[v8s_are_slow]

no one has an opinion on my log?

 

[diambo4life]

haven't checked the plugs lately. but i'll have to do it here soon. not sure how accurate this would be since i don't know my exact base timing. but i just did a log week before last and haven't driven the car since. did a 3rd gear run starting at 3063 rpm and ran it to 7031 rpm.

i'm trying to figure out how to copy and paste the info from the pl viewer from pocketlogger. but i'll give a brief overview real quick.

fuel trim low 105
fuel trim mid 108
fuel trim high 97
coolant 200

and here's a lil chart for some of the info. guess i'll just have to type out each reading. from left to right....rpm, knock, timing, and O2's. only listing from 5531 rpm and up cause that's where the knock starts (not to mention it's way more than i wanna type).

5531, 0, 29, .86
5531, 3, 29, .86
5844, 6, 29, .86
5969, 13, 26, .86
6000, 12, 27, .86
6094, 12, 27, .86
6563, 23, 25, .86
6719, 22, 25, .86
6813, 22, 26, .86
7031, 21, 27, .86
7031, 28, 25, .71

the pl viewer cut off the end of the log for some reason but on my palm, after i let off the gas, it shot down to 6312 rpm and knock went to 1 and then the 5500 and 0 again. so it went away pretty quick.

at the moment i have some bosch plugs in there that are pretty dang new. think they're regulars but i have the bpr7's ready to go in when i get the chance (dang broken foot and surgery. uggghhhh!!!!). anyway, ya'll tell me whatcha think. laters!

scott

p.s. i made a typo earlier. i'm not running 1250 at 65-70 mph on egt's. it's about 1300-1350.

It's pretty obvious what your problem is. First of all, don't even look at those O2 values. Your timing advance is sky high. I bet your airflow values (as seen on the logger) are below 1606Hz from leaning out those injectors. You need to get a chip to compensate them. Once you do that, your knock will disappear with minor tuning.

REPEAT: You are not going to tune out that knock without getting a KD-chip first.

 

[v8s_are_slow]

talking about a keydriver chip? where would i get one of those and for how much? and why would i need a chip to compensate? i thought that's what the maft was for????

 

[diambo4life]

www.keydiverchips.com or www.dsmchips.com

I will try and put this in a nutshell. Well, the MAF-T pretty much works like an AFC. It modifies the airflow signal. Basically slows it or speeds it up to deceive the ECU. Basically, when you add % on the AFC, you increase the airflow # the ECU sees and vice versa. However, this is best when a small range of adjustment is desired ie. using injectors slightly bigger than stock. Now with 650cc's, which are quite bigger than stock (>30%,) you're forced to use the same correction (on airflow) with the MAF-T or AFC. By doing so, the timing will get altered as well (since it's dictated by airflow as well.) Remember, with the MAF-T, you can only control the airflow and cannot control the timing. With the ECU seeing lesser airflow, you will get more aggressive timing since the ECU isn't really aware that you are pushing that 22psi for example. It thinks you are just cruising at some low rpm. Get it? That's the simplest way I can put it.

At WOT, without the chip and a MAF-T correction for 650cc's, you may see a max of 1700-1800Hz if you have a "big" turbo. However, with the chip, you may see closer to 2500-2600Hz at the same boost level. That makes a big difference on your timing advance through the RPM range and will consequently affect your knock. In this case make it easier to tune out.

 

[v8s_are_slow]

ahhh, okay sweet. guess i'll have to look into it pretty quick then i guess. just wondering, but how much of a difference could i feel in the seat of my pants once my knock is gone and timing pulled back? very noticeable? just curious. thanks for the info. scott

 

[BoostedTalonTS]

I've been reading about a lot of people who are running the 1.3 version of the MAFT that have encountered a lot of knock... This may help you:

http://www.fullthrottletech.com/forums/showthread.php?t=152

To sum it up, try temporarily swapping your hacked 1G mas back in and log it. -Many have found that the older version 1.3 MAFTs had some issue that actually leads to "creating" knock. Apparently, this was fixed in the later 2.0 version MAFTs.

I personally researched this before deciding to go with a 2G MAS, SAFC, and reflashed EPROM myself. Added a set of revised lifters and I don't see any knock counts that are higher than 3-5 counts at any RPM range, under the most amount of boost that I've run so far on my rebuilt head (about 14-15psi). So far, so good. (I can't wait to turn it up!!)

 

[sweet97]

What's bad with the high timing? 1 click to the plus side of his maft on the WOT knob should back off the timing and decrease the knock. Still confused about the timing. If he had that timing but no knock would that be good? i am learning totune and found my dwnoipe rubbibg onthe transfer case so I will bend that away. This is a good post on causes of knock besides tuning! mark

 

[Joesmoke]

Psychlow,

I have edited my post above to reflect what I was trying to say more clearly.

 

[diambo4life]

The V2 just increase the adjustments points from my understandng. I have the Ver. 1.3 and the KD compensated chip made the biggest difference.

You can still adjust the tip in point but this guy is having absurd amounts of knock at WOT in the 5-7K range. A V2 MAFT will not exactly "fix" that.

If you read my first post, you will see what needs to be fixed. Having another (say 10 additional) adjustment points when you are still peaking at some 1800Hz in 3rd gear at WOT will not do squat for you.

v8's-are-slow...Yes, you will notice a BIG difference in power when the car pulls with timing in the 18-20 range all the way to redline on pump.

I could hardly run 15psi without getting ton of knock. After getting the chip, running 20psi on pump gas was not a problem anymore.

 

[v8s_are_slow]

okay i bought a stage 3 chip today. so guess when it gets here i'll see how well that helps.

question about timing though. what kinda timing should i be looking at when i'm at full throttle or thru the rpm range? i know at idle it should be at 5 correct?

also as far as the lifters go, if they're not making noise at idle, is it possible for them to be making noise at a higher rpm that i can't hear? my car's already pretty loud anyway. but they're pretty quiet at idle. if they could make noise at a higher rpm and not a lower, how could i detect it so i know that's the problem? guess i'd just have to change them out and see if the knock goes away? i doubt this is my problem (sure the chip will help out) but just another thing for other people to check on.

 

[diambo4life]

Set your base timing to stock (5deg +/-2* BTDC) with a timing light. When you get the chip, zero out everything (MAFT and AFC if you have one,) adjust your fuel pressure and lower the boost level to like 12 or 13psi - then start tuning as you raise the boost slowly. Your timing normally would be in the 18-22deg and peaking at around 18-19deg at redline if everything is ok. Just remember you can not really adjust your timing (like the DSMlink guys), so if it's waaay off, find out why it's so.

I think a good idea is to work on one thing at a time - this way, you can isolate the problem and know what the fix is. If you change 2-3 things at the same time and your problem disappears, you will not really know what the problem was to begin with. If you still keep getting insane amounts of knock even after getting the chip installed (and tuned), look at the lifters then. My car ticks like crazy sometimes but it never triggers knock so I don't even f*ck with them. I got used to the ticking a long time ago.

 

[v8s_are_slow]

well, i have a tial and the lowest my boost will go is 17. so guess i have to start from there. but i'll still 0 everything out and start all over once i get the chip.