SoCalRedLine

iTrader: (2)

So, I have been trying to figure out why I was getting 1-18 counts of knock whenever i would lightly accelerate around 0psi. I noticed that it correlates DIRECTLY to the GM 3-port solenoid kicking in. It happens whenever the WGDC is >0% at low boost (it also happens at high boost, you just cant really hear it over the loud motor)

You can hear an audible clicking noise when this all happens, and most confuse it with a bad PCV or their BOV fluttering. So, in an effort to figure out where the clicking was coming from, i removed my pcv and unplugged the vac line to the BOV (not a good idea...) and went out and listened to the motor for the noise. While watching my Evoscan GPS logger I noticed that the noise was still there, and it started as soon as the WGDC went above 0%, and it went and came back everytime i repeated the process. Unfortunately i forgot to click the 'log to .csv' checkbox so there is no log from that test run. Im going to try and get a good log to show the direct correlation when this 'clicking/flutter' happens. Ill post logs this weekend after I finish midterms.

Ill also try a few solutions to try and deaden the noise of this solenoid, like soft mounting it and/or wraping it in sound deadening. Hopefully one of these will work to remedy the problem.

tephra

iTrader: (6)

yeah just use some foam between it and the chassis - should fix the clicking noise..

GST Motorsports

iTrader: (8)

Is the 3 port mounted on the stock solenoid mount which has the little rubber cushions?

- Bryan

ixbreaker

iTrader: (3)

I had a simlar problem with my prodrive bcs. I just increased the minimum load req'd for boost control in those areas where you hear it. Also, if your running 100% wgdc under certain load it needs to be turned off as well.

So this noise is enough to be detected as false knock? wow... i just though it was annoying hearing it flutter all the time...

Jack_of_Trades

iTrader: (17)

I'm surprised this is enough for the knock sensor to notice anything. Especially since the BCS is mounted to the frame rail and the engine is insulated from the frame rail with rubber engine mounts. Sure is a whole lot of obstacles between the knock sensor and the BCS which could absorb that noise.

fostytou

iTrader: (15)

My sentiments exactly. I don't have any proof to the contrary though. I'll be insulating mine either way, but I definitely heard my stock BCS, AEM, and EGR all do the same thing when it was cold outside.

ixbreaker

iTrader: (3)

Surprising indeed...especially since it's not just 1 or 2 counts. He said upto 18!?!? is that a typo?

I do notice it more when it's cold (~50 F) outside as well. During the afternoon where temps are in the ~70s I never hear it.

SoCalRedLine

iTrader: (2)

I couldnt get the OEM bracket to fit with the GM-solenoid attached. Im also very bad at Tetris, which may be unrelated... But it is bolted using the tab that is attached to the solenoid, bolted directly to the chassis in the stock location.



no typo. Ive seen up to 27 on occasion, and it quickly backs off when I go below the WGDC load limit (76.8%load @2.5-4k) and the WGDC goes back to 0%. It doesnt pull any timing out of the car so its as if it ignores the knock, but Tephra's CEL light sure goes crazy.
It does correlate to what you said about cold temps, tho. Ive only noticed it when the car is cold and the solenoid hasnt warmed up yet. I kinda wonder if the WGDC v. Temp table has anything to do with the noise.

I am thinking about bumping up the load limit for WGDC control at those RPM's to see if it will help reduce the noise, but that just means the noise will move to a higher load or a higher RPM.

I have noticed the knock sensor picking up road vibrations and bumps. Its pretty sensitive. The noise is loud enough for me to hear in the cabin over my chattery clutch and loud exhaust, so I'm certain it must be loud enough under the bonnet to make the knock sensor think the motor is knocking.

I currently dont have internet at my house (i moved), but I will try to post logs from tomorrow morning on my way to school. ill log coolant temps and ambient temps, as well as the WGDC and knock.

P.S. anyone else with an iPhone HATE that this forum comes up in mobile mode?!? That has been keeping me off here for a bit too... wish the "go to normal mode" button actually went somewhere...

GST Motorsports

iTrader: (8)

What couldn't you get to fit? I've installed pierburgs with no issues and they are basically the same size as the GM.

- Bryan

Jack_of_Trades

iTrader: (17)

Hitting a bump in the road will move everything under the hood a great deal, especially the long block. To say the plunger in the BCS can exert a comparible force would seem fairly unlikely. I would focus more on 2 things:

• Is the extra current demand of the COLD bcs causing circuit issues in the ECU?
  
• Do the settings in the BCS table affect anything else that could be contributing to the glitchiness?

I'm not saying your theory is wrong, just that I personally would like to explore all avenues before settling on the noise traveling to the knock sensor.

merlin.oz

Interesting thread here, any further developments?

THUB

iTrader: (5)

I've never personally heard my BCS click at all, but if it's hitting just the right frequency, I could see it setting off the knock sensor. It could also be interference within the ECU like a ground offset (term I took from my wide-band's manual ) or something. Is everyone using a resistor (can't remember the exact value) inline with their solenoid?

mrfred

iTrader: (50)

Interesting thread. I've got my GM BCS bolted directly to the tranny (using one of te slave cylinder bolts), and so far no additional knock. I've never been able to hear my BCS operating with it mounted in the car. On the benchtop, its not appreciably louder than the stock solenoid.

ziad

iTrader: (1)

i got a perrin.. and it bolted up to the stock bracket (with the rubber gommets) and i only needed to drill one hole in the bracket

tweakdsm

iTrader: (38)

I get knock when I rev the engine or drive the car at slow speed and hit gas pedal slightly ones i got WOT , thru 3rd and 4th 0 knock, im thinking to replace knock sensor....

my engine is build with muck balance shaft.