How can I get rid of this 'phantom' knock?

[MindBlowin03]

Ok, ever since I got the new car running it has had knock basically as long as I have my foot on the gas. I get 0-4 counts at idle alone, and 30-43 with any gas what-so-ever(even in neutral). At WOT it will sometimes clear up, meaning knock will go away and car will pull fine. That only happens about 1 of 5 pulls though. Listening to the engine with the hood open you cant hear anything unusual at all. Here is just a list of stuff I can think of to help.

- Bottom end sounds fine with no unusual noises. Also, pistons were all cleaned nice when I installed the head.
- New head installed
- Lifters are not loud at all(cant hear them even when ear is near valve cover)
- Stock injectors dont seem to be unusually loud. Also tried installing my 650s with a rough tune, and that didnt help at all.
- Base timing set to ~5*(seems to jump a bit with cams installed).
- Rechecked my camshaft timing and everything is perfect.
- Although my knock sensor looks brand new I tried another with no success. I also tried tightening it at differant torques which didnt help. Also tried a metal and rubber washer, neither helped at all.
- Although my ECU looked to be in perfect shape I also tried another with no success at all.

The only other things I can add are that the car drives pretty decent. Even when the knock is at 43 counts while normal driving the car seems to drive ok. Also, if I set me base timing lower than 5* the car has NO power at all. It just falls on its face until mid RPMs then drives ok.

If anyone can give me something I can try out it would be appreciated.

 

[DSM90AWD]

Filling out your vehicle profile with any "mods" would be a good start.

Not sure if you've visited the Phantom Knock List on Yahoo Groups, but it has years worth of good information and suggestions.

In my case eliminating the PCV and instead running an open line to catch can along with disconnecting my FPR solunoid helped me (did both at once so don't know which helped more).

There are other reports where bad grounds, loose motor/trans mounts even the exhaust/tranny making noise causing what the ECU percieves as knock.

In any case it's just a matter of trial and error to see what works for your car.

BTW.. there are other options. DSMChips.com and DSMLink both offer EPROM mods that will eliminate part throttle knock by ignoring the knock signal under certain Throttle/Airflow points. This is more a last resort as it does not fix the underlying problem, more a bandaid so you dont' end up pushing the car off a cliff in exasperation

 

[VBGSX]

Do a simple search for phantom knock and you will get lots of responces.
I've answered a bunch of them in the past week alone.
Here's one post you might want to look at:
http://www.dsmtuners.com/forums/showthread.php?t=183922&highlight=phantom+knock

Also look for anything loose that could be shaking about.
You could have phantom knock from lifters and you not really hear it to bad(most common it seems)
Like I said, look at the above thread and see if any of that sounds familiar and let us know.
Good luck

***edit***
DSM90AWD, good extra info

 

[MindBlowin03]

I filled my car info in(thought I had it in there already actually).

DSM90AWD... I dont have my FPR solenoid, but I do have my PCV still(going into a catchcan). I checked most things over and everything seems ok. No loose/bad grounds, no loose bolts, no noticable noises, etc. My motor mounts are window weld'd, so I know they arent the problem.

VBGSX... I did a search and tried about everything I read on here and DSMtalk. Thats mostly why Im finally posting about it. I definately dont have anything rattling, and I highy doubt its the lifters simply because you cant even hear them.

One thing I have heard, and Im wondering what you guys think. Taking the knock sensor and threading it into the back of the intake manifold where the factory bracket goes into. You ever hear of that before?

 

[MindBlowin03]

Some more info...

If I slowly raise the RPMs in neutral it wont really knock, but if I blip the throttle at basically any RPM then it will knock crazy again. During regular driving it seems anything over 10% TPS gets me alot of knock. I did do one log at WOT. First gear knocked like crazy(36counts/6* timing), second gear was good(1 count/16* timing, shifted at 6k), and third gear wasnt too bad I guess(7 counts/13* timing). Another thing I notcied is that my o2 is reading about .80-.82v during the pulls.

 

[DSM90AWD]

One sure way to find out if it is "real knock" is to drain your tank and use some VP110 Unleaded (or other high octane gas) for a similar pull. If you still have knock then it is not pre-detonation knock.

You said your knock sensor was in good shape and tried another with the same results. Did you happen to inspect the leads to the KS (i.e. harness itself) and make sure there is no damage? When the ECU detects a faulty KS (or that it is missing) it will go into "safe" mode and register knock at all time in order to keep timing low.

 

[TERBOLASER]

hey well will the ecu read a cod e for the knock sensor in that situation ?
beacue i feel that im in that same boat i get crazy knock like that driving for no reason retards timing and throws a crap load of fuel in there. cause the manifold to glow under normal driving since combustion happens so late in the cycle. its some thing that happend just randomly happened but at the smae time can the ecu its self be at fault for all this.?

 

[MindBlowin03]

I tried yet another working ecu and this still happens. I borrowed an AFPR off a buddy and Im gonna try that on there and see what happens. Hopefully once I get my fuel pressure straightened out the car will run alright.

TERBOLASER... The ecu will throw a code if the KS is unplugged, but not if its bad. If the KS is bad you will just get weird knock readings or 'phantom' knock. The ecu can also be at fault, probably because of leaking caps. In my case Ive tried replacing both and I still have the problem.

 

[MindBlowin03]

Another update...

I slapped on an AFPR and set it to 36psi base and the car still knocks pretty much all the time. One thing I did notice is that on a WOT pull, the car will knock a majority of the time. Sometimes it dose knock, but sometimes it dosent(maybe the RPM starting point affects this?). Anyways, the times it does knock, I just let off the gas for about a full second and go WOT again and the knock does not come back and the car pulls great again.

Any idea what else I can try?

 

[joeym4130]

In my case eliminating the PCV and instead running an open line to catch can along with disconnecting my FPR solunoid helped me (did both at once so don't know which helped more).

Is this common in trying to relieve pk? Just wondering, and what is the reasoning behind it?

 

[MindBlowin03]

Id like to know the reasoning behind this as well.

 

[DSM90AWD]

Is this common in trying to relieve pk? Just wondering, and what is the reasoning behind it?

My situation was somewhat different (but related). I'd get pretty good knock btw shifts when upshifting during spirited driving.

Since the PCV only opens when the manifold pressure < crankcase (i.e. btw shifts) I speculated that since ~90% of the crankcase vapors exit the PCV into one cylinder this could ultimately affect that cylinders AFR causing "rich knock".

You could also parallel this with the EGR valve which creates an opposite impact but is distributed across all cylinders. Though if one (or more)of the EGR outlet ports in the manifold were to clog (not a stretch), it would reason that the remaining passages would pass more gas and could cause a lean condition in those cyls.

As for the FPR Module, it shares a vacume with the FPR and during cold starts "boosts" your base Fuel Pressure by closing off the vacume to the FPR. My "theory" is that taking this module out of the loop would cause my FPR to react quicker to changes in boost/vac and removes a potential boost leak (especially if it was failing).

Sorry for the novel .. but after having tried many different things on my own car this is what worked for me. Others have tried similar things which did not fix their problems so your results may vary.

 

[fast1g]

If you are as desperate as I was I have a suggestion, People have been tuning without knock sensors for along time. I had a max knock count of 43 at idle it pulled all kinds of timing, I tried everything aswell nothing worked. What you can do is unhook the sensor get a nut that fits and hook up a ground from the sensor to the chassis. You will get zero knock no matter what. My car ran awsome after that it was one of the best mods I did at that time WTF . I have a 6 bolt and I thought crank walk was unheard of well I had .50 play. Some times it has knock for a reason. Do what you want I only noticed the problem b/c I built a 2.4 so do it at your own risk.

 

[DSM90AWD]

What you can do is unhook the sensor get a nut that fits and hook up a ground from the sensor to the chassis. You will get zero knock no matter what. My car ran awsome after that it was one of the best mods I did at that time WTF .

Remember the saying "your car runs fastest right before it blows up".
Running a "dead" Knock Sensor on a turbo car is just plain stupid

 

[me612]

This sounds exactly like what is going on with my car right now. I've tried new injectors, new Sensor, resetting timing. Once I get my daily driver, I'm thinking about doing the MCCC cleaning, getting revised lifters, and seeing what that does for me.