General Crazy knock under low throttle. Has anyone had that?

[Newlogics]

Originally posted by Newlogics
Ok, here are some logs.
(I'm at work,so I can't download the from my palm. I had to redraw them, but ti's enough to give abasic knock pattern.
Both scenarious are in 3rd gear starting at 2300rpm.
Before the washer:

You must be logged in to view this image or video.

After the washer:

You must be logged in to view this image or video.

As you can see, the washer didn't really decrease knock count, but rather changed it pattern and duration. Also it has reduce its occurence.

As you can see in the first pic, without a washer, once knock comes on, it won't go a way untill throttle is released.
With the washer (pic 2), knock does come on every so often, but begins to fade right away.

 

[FastRthenU]

So the question is. What the hell does this tell us. How would MCC, and putting a washer in affect what is happening. It is obviously not real knock. But somthing tripping it. So how would MCC help, to make this go away. Its cleaning somthing that makes this stop(For a little while) I did not say before that I sprayed it into the spark plug hole. But I did, and let it sit over night.

So what could cause the knock sensor to trip that much under such low throttle. Then go away once you let off the gas? As I said before if I race my car at a stand still it has never done this. I think we need to find the common denominatior, in all of are case's

 

[FastRthenU]

I Pm'ed one of the wiseman on this board. Candela
this is what he said about the problem. hope this can help

Well i was hoping you could tell me what you think is your problem. Phantom (not tuning based) knock that I know of that have caused crap like this to happen are the following:
-too loose of a knock sensor
-too tight of a knock sensor
-faulty knock sensor
-some irregular vibration (such as a loose axle bracket...etc) causing the sensor to pick up "knock"
-to tight of a timing belt/other belt causing a sort of sound wave that the knock sensor seems to pick up. I know this sounds silly but Ive seen it on 2 different cars including mine
-boost leaks
-improper seal of the wireing on the back of the knock sensor which causes a inconsistent signal...voltage=knock in which cause a little silicone sealant does the trick
-piston buildup of carbon
-screwy engine mounts
-lifter tick
....etc there are more than this that people have thought is the cause, but you really just have to narrow this down. Im not sure yoru specific situation which is why I asked. So many people have ha dtrouble with this before and most seem to eventually figure it out. A knock count of 43 is as high as the ECU will read out on any form of logger and this results in as little as 5* of timing in some cases. Anyhow, if you see this crap you can most liekly set aside the worry that your motor is getting banged up as its VERY rare that someone is dumb enough to cause a count of 43. Although this will still cause the sensor to retard timing which sucks for power, its not hurting anything. Try to go threw the list and eliminate all of this stuff. Anyhow all I can really tell you is to try and figure this out yourself. Its hard to do, especially over the internet , but you have to do it. Anyhow good luck and I hope I helped a little bit.

 

[Newlogics]

Originally posted by FastRthenU
So the question is. What the hell does this tell us. How would MCC, and putting a washer in affect what is happening. It is obviously not real knock. But somthing tripping it. So how would MCC help, to make this go away. Its cleaning somthing that makes this stop(For a little while) I did not say before that I sprayed it into the spark plug hole. But I did, and let it sit over night.

So what could cause the knock sensor to trip that much under such low throttle. Then go away once you let off the gas? As I said before if I race my car at a stand still it has never done this. I have a qustion. How many ppl have this problem, that still have there balancer shafts hooked up. Just out of curiousity. I still have mine in. I think we need to find the common denominatior, in all of are case's

Well, as I understand it from reading likes posted above, there could be substantial carbon buildup on your pistons. If it's thick enough (and it's very possible, especially if you blow oil into your intake), it will actually hit the underside of the cylinder head. I assume that's an extreme case, butit doesn't seem all that unlikely.

I've completely eliminated lifters from the suspect list, so there isn't much left. I will try to lift the car up and give it some throttle while applying brake (to simulate a load). I assume something that is strong enough to trip knock sensor into reading maximum knock, should be noticed easily.

 

[Newlogics]

Originally posted by FastRthenU
I Pm'ed one of the wiseman on this board. Candela
this is what he said about the problem. hope this can help

Well i was hoping you could tell me what you think is your problem. Phantom (not tuning based) knock that I know of that have caused crap like this to happen are the following:
-too loose of a knock sensor
-too tight of a knock sensor
-faulty knock sensor
-some irregular vibration (such as a loose axle bracket...etc) causing the sensor to pick up "knock"
-to tight of a timing belt/other belt causing a sort of sound wave that the knock sensor seems to pick up. I know this sounds silly but Ive seen it on 2 different cars including mine
-boost leaks
-improper seal of the wireing on the back of the knock sensor which causes a inconsistent signal...voltage=knock in which cause a little silicone sealant does the trick
-piston buildup of carbon
-screwy engine mounts
-lifter tick
....etc there are more than this that people have thought is the cause, but you really just have to narrow this down. Im not sure yoru specific situation which is why I asked. So many people have ha dtrouble with this before and most seem to eventually figure it out. A knock count of 43 is as high as the ECU will read out on any form of logger and this results in as little as 5* of timing in some cases. Anyhow, if you see this crap you can most liekly set aside the worry that your motor is getting banged up as its VERY rare that someone is dumb enough to cause a count of 43. Although this will still cause the sensor to retard timing which sucks for power, its not hurting anything. Try to go threw the list and eliminate all of this stuff. Anyhow all I can really tell you is to try and figure this out yourself. Its hard to do, especially over the internet , but you have to do it. Anyhow good luck and I hope I helped a little bit.

Well, in my case its prety narrowed down:
-too loose of a knock sensor - Checked
-too tight of a knock sensor - Checked
-faulty knock sensor -Replaced
-some irregular vibration (such as a loose axle bracket...etc) causing the sensor to pick up "knock" - Knocks while stoped and revving in neutral, so NO

-to tight of a timing belt/other belt causing a sort of sound wave that the knock sensor seems to pick up. I know this sounds silly but Ive seen it on 2 different cars including mine - No, TB changed, belts adjusted
-boost leaks - None.
-improper seal of the wireing on the back of the knock sensor which causes a inconsistent signal...voltage=knock in which cause a little silicone sealant does the trick - New sensor

-piston buildup of carbon <-pending
-screwy engine mounts - No
-lifter tick - Replaced lifters.

 

[FastRthenU]

Well I have a feeling that what ever is causing this on your car. Is the same reason mine is doing it. When you replaced your knock sensor, was the old one bad? or did you just replace it to make sure? I hope that we can figure this out.

 

[Newlogics]

Originally posted by FastRthenU
Well I have a feeling that what ever is causing this on your car. Is the same reason mine is doing it. When you replaced your knock sensor, was the old one bad? or did you just replace it to make sure? I hope that we can figure this out.

The old one didn't look bad.
I replaced it to narrow down my list of suspects.

I'll try that MCCC soon and hopefully that will do it, otherwise I'm forced to think that my internals are knocking (like crank journals out of wack or something.)

 

[FastRthenU]

Humm. Well that makes me feel a bit better. Hopfully its my knock sensor. Because I know It was bad, and now its over tightend. But I hope you can figure out what is causing yours.

 

[JCG-GSX]

Well, keep us posted, and let me know where you find that MCCC. I searched around a handful of auto parts stores and have so far come up empty-handed.

 

[LandoAWD]

MCCC
M is for MOPAR.

Try a Dodge dealership.

 

[Newlogics]

Originally posted by JCG-GSX
Well, keep us posted, and let me know where you find that MCCC. I searched around a handful of auto parts stores and have so far come up empty-handed.

Here's place:
http://www.buymopar.com/store/chem.html

 

[painmaster]

Most of you guys are saying that your high knock is at low RPM and low load. Are you getting the knock will driving or just reving? This may be completely obvious ,so please don't let this offend you if it is, but when I let other people drive my car I notice that they are allways under reved. I didnt think much of it till I was logging one day and saw tons of knock while just slightly accelerating.

What happens if you keep your RPMs up higher? Never shifting into 2nd or 3rd without having at least 4500RPM.

I get a knock count of 43 when I accelerate from a light with low RPM. My knock will stay maxed completly through first gear until I shift at 4500rpm at which point it drops to zero. If I rev up to somewhere around 5000 RPM and then launch hard I have 0 knock.

When you launch hard do you have knock?

 

[FastRthenU]

Really?

 

[painmaster]

Yep! You must not drive around under-reved. I would have thought you knew this!

You must be logged in to view this image or video.

j/k

 

[Newlogics]

Originally posted by painmaster
Most of you guys are saying that your high knock is at low RPM and low load. Are you getting the knock will driving or just reving? This may be completely obvious ,so please don't let this offend you if it is, but when I let other people drive my car I notice that they are allways under reved. I didnt think much of it till I was logging one day and saw tons of knock while just slightly accelerating.

What happens if you keep your RPMs up higher? Never shifting into 2nd or 3rd without having at least 4500RPM.

I get a knock count of 43 when I accelerate from a light with low RPM. My knock will stay maxed completly through first gear until I shift at 4500rpm at which point it drops to zero. If I rev up to somewhere around 5000 RPM and then launch hard I have 0 knock.

When you launch hard do you have knock?

Welcome to the club.
Only it is not 'just another perk of the engine design'.
It is a problem, and it's not normal. I've poured some MCCC into the pcv hose over the weekends, and it helped situtation quite a bit. Next thing I plan to do is to pour some of it directly into cylinders and let is soak for a night.

Anyone else tried anything?

P.S. I've also installed 660s over the weekend, and now can go full boost WOT in 5th gear without knock or rising EGTs. They're awesome!

Another observation:
I seem to get most knock when engine has too little load, but rpms are fairly high. For ex. when I'm going 40 in 2nd, but not accelerating.

 

[FastRthenU]

as i said. Mcc is just a band aid. it will come back

 

[jdk906s]

Diagnosed mine: 3" exhaust was lightly bumping into the rear carrier bearing. Tweaked rear bracket - 100% fixed.

 

[LandoAWD]

Originally posted by jdk906s
Diagnosed mine: 3" exhaust was lightly bumping into the rear carrier bearing. Tweaked rear bracket - 100% fixed.

Could this REALLY create the frequency that the sensor picks up?
Wondering, cause my exhaust rattles a little off the front care bear under 2k. Remember, though, the sensor picks up a frequency of sound.

 

[FastRthenU]

This thread is back from the dead

 

[Newlogics]

Originally posted by jdk906s
Diagnosed mine: 3" exhaust was lightly bumping into the rear carrier bearing. Tweaked rear bracket - 100% fixed.

Can you describe procedure a little more ?
This seems to be interesting.. (mine started knocking abound after I had 3" downpipe installed)

 

[jdk906s]

Sure, first off it didn't fix 100% of my knock - just the insane and common phantom knock I was getting.

It was fine with the 3" catback before, but when I put on the 3" downpipe it all started up so I started there. (3" bushcur slip fit, no cat)

First off it was lightly tapping on the rear carrier bearing... I unhooked the far passenger side mount, then used some of that metal holed strapping tape to hold it slightly more toward the other mount so it shifted the muffler ever so slightly toward the center of the car.

I also found that it was lightly tapping against my shield by the drive shaft. A quick cut of about 4" of the metal there with my dremel made short work of it.

I still think I'm getting a little phantom knock, but I think it's cause by my sensor being near death. It no longer reads 42, it'll just read weird blips of say 6 for 1 second or 2 on low throttle and then go away. Nothing near what I was.

I tested it though, I hooked the muffler back up and it resumed massive knocking. My hypothesis: The light metalic "ping" of the exhaust tapping the carrier bearing or metal shields is very similar to detonation therefore the sensor should pick it up. I think this problem is increased by weak/too tight/too loose knock sensors.

 

[4doorsNmore]

Sure, first off it didn't fix 100% of my knock - just the insane and common phantom knock I was getting.

It was fine with the 3" catback before, but when I put on the 3" downpipe it all started up so I started there. (3" bushcur slip fit, no cat)

First off it was lightly tapping on the rear carrier bearing... I unhooked the far passenger side mount, then used some of that metal holed strapping tape to hold it slightly more toward the other mount so it shifted the muffler ever so slightly toward the center of the car.

I also found that it was lightly tapping against my shield by the drive shaft. A quick cut of about 4" of the metal there with my dremel made short work of it.

I still think I'm getting a little phantom knock, but I think it's cause by my sensor being near death. It no longer reads 42, it'll just read weird blips of say 6 for 1 second or 2 on low throttle and then go away. Nothing near what I was.

I tested it though, I hooked the muffler back up and it resumed massive knocking. My hypothesis: The light metalic "ping" of the exhaust tapping the carrier bearing or metal shields is very similar to detonation therefore the sensor should pick it up. I think this problem is increased by weak/too tight/too loose knock sensors.

Man, that's thinking outside the box!! I hadn't even thought about exhaust rattle, but my Galant has the same light throttle phantom knock describes as everyone else and it has a 3" downpipe on it too. It's had the phantom knock issue as long as I've owned it, but then again, it's had the 3" downpipe as long as I've owned it. The motor has been out of the car and checked over so I know that everything is good internally.

I will definitely have to check into the exhaust and see if I'm having the same problem.

Thanks!!!

 

[GVR4592]

Can you describe procedure a little more ?
This seems to be interesting.. (mine started knocking abound after I had 3" downpipe installed)

It's probably due to boost creep. Do you have a boost gauge?