gazzy2000

more good info from a thread here: http://www.honestjohn.co.uk/forum/post/index.htm?t=33615 Although the knock sensor is tuned* to pick up the vibrations caused by knock, typically around 4KHz, it is possible for a knock sensor to 'hear' other signals which the ECU interprets as knock. Things that are loose, rattling or impacting together can confuse a knock sensor. As the ignition advance map is adaptive, it is possible for the ECU to learn an incorrect mapping if the knock sensor is hearing things. *The sensor may be tuned by torquing the attachment bolt is the bolt is mechanically in parallel with the piezo crystal. If the bolt is too loose, or too tight, the centre frequency of the sensor can be incorrect, so the sensor might pickup the valve train noise rather than knocking, for example. Also, as the knock sensor signals are very small, they are easily swamped by electrical interference and noise. The noise may be interpreted by the ECU as knock. I have ended up fitting metal braiding over the knock sensor wires, effectively extending the ECU metal casing all the way to the sensor, in order to shield out electrical noise in one particularly difficult case.

Just about forgot. ** DONT GET A FLASHING LED ** just get a normal one as a flashing one defeats the purpose, so ask at jaycar for a 12v NON flashing LED with resistor

Yip pics 2nite no wuckers. Just started a a whole thread on DIY knock sensor listening

Yea, you cud for sure, the boost gauge will tell you where you are at, of course you have to know what you max boost is and that your gauge is right. Have to use special 12v LED with resistor wired in, jaycar has them. TTs have two boost solenoids so i guess youd have to run two LEDs, get a green for primary and a red for secondary. While your are at jaycar get the right meterage twin core cable (just small gauge speaker cable with do at a guess 4-5 meteres) and medium cable ties. Plus i simply used scotch lock joiners to tap into the boost solenoid wiring ( i post pics tonight) May be a mission to get to the secondary boost solenoid in the BBOD. But it really is worth it just to know where you are at with the boost etc.

Originally this is the link i used http://home.netcom.com/~bsundahl/knock/listen/listen.htm#Recorder I first tried using the knock sensor with no amp, it was just too quiet. I used an old knock sensor rather than tapping into my main one. I wired it up ruffly for a start on my desk and used the free software called spectrogram to test it Here is the amp kit you need from jaycar, as per this link http://home.netcom.com/~bsundahl/knock/listen/listen.htm#Recorder Jaycar has all the stuff you need incl the wee box http://www.jaycar.co.nz/productView.asp?ID=KG9032&keywords=kg&form=KEYWORD

Hi, I started this thread due to finding a DIY knock sensor kit on the net here: http://home.netcom.com/~bsundahl/knock/sound/KnockSounds.htm I got all the things i needed from jaycar. Myself, i need to determine if detonation (det) is present simply to write off knock being an issue for my boost problem (of which is a work in progress)and i just dont want to pay a tuner $75+ to tell me. Plus i have found with most tuners you have to talk to their belly button so they can hear you properly because their heads are so far up their own assss. A knock sensor is in its simplist form is a microphone, youtube and the internet has loads of info on knock sensors and det, YT even has vids on what DET sounds like. If you are one of these ball bags that bypasses the factory boost controller and cranks the boost way high with no other mods to compensate that extra boost, well firstly your are a ball bag and secondly, you can save some bucks and save your engine by using this DIY knock system to check for det. Once i have proven the concept (maybe with kooms help as he has done this too) we will put up pics etc, but the above link will get you started. Here is some info i found useful from threads when i first started learning about knock sensors: FROM: http://www.iwsti.com/forums/water-meth-injection-nitrous-intercooler-cooling/162723-new-meth-failsafe-idea-using-knock-sensor-signal.html -I'm not sure if the knock type of timing pull is exactly what you want. But, I'm not really the person to chime in on this. It may be that pulling timing in the manner that the other failsafes do it is gentler or something. -There are essentially two types of sensors that the knock sensor could be. One puts out a voltage (probably from 0-5 volts) and the other is a pulse width modulation (remember morse code...it's sort of like that...sort of). -IIRC the knock sensor on a subaru is a voltage (aka analog) signal of 0-5v. -I think the ecu pulls timing only when it receives several knock events (knocks?). I'm not sure if a continually applied voltage to show one large knock would work. You may need to do several knock-on knock-off repetitions to get it to trigger a timing pull. I know on the hydra you get a knock level and can tune a knock table so this trigger value changes. Not sure about the stock ecu. -http://www.northursalia.com/modifications/misc/wiring/04_STi_ECU.pdf says that the knock sensor is at 2.8 Volts at idle. I'm guessing this is your no-knock condition. FROM: http://forums.nasioc.com/forums/showpost.php?p=3257963&postcount=4 I think the you believe there is some threshold voltage from the knock sensor that the ECU interprets as knock. This is not the case. First, the ECU limits the times at which it montors the knock sensor to what are called "knock windows." A knock window is the period of time (measured in crankshaft angle degrees) during a power stroke when spark knock can actually occur. The ECU also varies the start/end of the window based on ignition advance and engine RPM. Only monitoring the knock sensor during knock windows allows the ECU to ignore the sounds of valves falling into their seats, which occur outside a knock window and are quite noisy. Also, the ECU uses another sophisticated method to distinuish knock from noise. During the knock window, it computes two values: the average noise level and the peak noise level, at the frequency that is characteristic of knock in the EJ20 engine. The knock subsystem only "declares" knock when the difference between these two values exceeds a threshold, which can be varied based on RPM and load. And finally, the ECU may sometimes retard ignition timing only after a certain number of knocks have occurred within some short time period. If no knocks occurred during that interval, the ECU might even advance ignition timing further.

Yip, its a 12v one from jaycar with built-in resistor. You can see the flashing lenght change with the duty cycle, its quite cool! Yea, its a good way to see if you ECU is causing boost issues electronically and if not you can start looking else where with confidence. PLUS - it really is the only way to tell if you are in safe mode or not, cause the ECU sure wont let you boost if it detects engine probs, and safe mode does not throw a CEL. ugot any pic of the wiring where u pinched the wires to on the solenoid - i might do the same ay bro.. that is a seriously good point u made - i will use that as one of the steps in troubleshooting for similar cases if i see any I will take some pics after work tonight, plus have a look at my DIY knock sensor listening device in my TT to single thread, just plugged that in too and it works real good!

Yip, its a 12v one from jaycar with built-in resistor. You can see the flashing lenght change with the duty cycle, its quite cool! Yea, its a good way to see if you ECU is causing boost issues electronically and if not you can start looking else where with confidence. PLUS - it really is the only way to tell if you are in safe mode or not, cause the ECU sure wont let you boost if it detects engine probs, and safe mode does not throw a CEL.

Well done, good to hear!

No worrys man, happy to help! Make sure you let us know how you get on aye! Cheers

Nup, piss easy man. Just be gental as a lamb and take your time http://www.scribd.com/doc/104227/How-Subarus-Factory-Boost-Control-System-Works-v11-01

Na, a wrecker will hook you up with a pill. Just reset your ECU afterwards and go for a drive to see if you get 15 PSI.

After all the bollocks i have been through testing boosting issues, i wud question any WRX that runs 10 PSI boost, as it may well be in safe mode The worst thing is "safe mode" dosent throw a CEL and runs the car really rich. My car boosts at 10 PSI with no mods, yes there is a problem right, i cud easily fit a boost tap as a work around and get 15 PSI, but the car will still be in safe mode, most likely running rich as well. So a boost tap wud only mask the problem. I reckon you should fit a pill and make sure its running 15 PSI stock standard before fitting any boost taps or controllers etc. WIth your boost gauge Youd know straight away if u had 15 or not. For more serious trouble shooting, when/if the ECU goes into safe mode it makes the duty cycle of the boost solenoid 0%, the best way i have found to test this is to put an LED across the Boost solenoid wires, run it into the cabin and tape on the dash, then watch the LED flash as the ECU dutys it on and off. If it does not flash, well that means the ECU is not controlling it, meaning possibly its in safe mode for some reason. Obviously your boost gauge will tell you that you are boosting 10 PSI in safe mode as well, but the LED tells you that its the ECU that is basically turning off boost control. If the LED flashes and you still have 10 PSI, well you rule out the safe mode theory and start looking at other possible causes.

http://subaru-offroad.blogspot.com/2009_02_01_archive.html

any CELs? no check engine light? I will hazzard a guess and say that the rich smell of fuel maybe casue the ECU is "safe mode" hense the low boost and richer mixture to be safer on the engine if it thinks there a problem. Thats my thoughts anywho

Hey, was that you that just brought my turbos of TM? LOL

cool, we are getting somewhere. Ok, so what about capping off the PVC system (on that inlet pipe where you fit yr DIY adaptor) so that you dont pressurise the engine internals and unseat cam seals etc, as per concerns in those links i posted? I had the engine out when i did the TT to single T conversion and cleaned all the hoses, so there really isnt any oil residue. CHeers

The car is running very rich under boost. I have been hving boost issues and need to eleminate these sorts of things. Yes i am aware of the adaptor (as per the links to web sites i posted earlier) and the concept of boost leak testing, but i am failing to understand what needs capping off so you dont get false boost leak readings. Also how you cud even posibly pressurise the inlet manifold in the first place, wudnt you need all valves closed which is not possible.

yip, i am not interested in vac leaks, its boost leaks i am looking for. I got brand new vac hoses alround. Hence the subject/title of this this thread that i started!

now your talking LMAO OR how about making a make-shift snorkle on the air box then drive it into a river up to the windscreen, leave it idling while you swim around it with a mask and snorkle looking for bubbles. If it stalls well you probably have a vac leak

i believe engine start or carb cleaner is the shizz

what about that spray and walk away stuff? that looks good too! LOL

is carb cleaner better?

Here is another link relating to the boost leak test, http://www.iwsti.com/forums/how-install/119676-diy-another-boost-leak-tester.html But what i am failing to understand (as were ppl in that thread) is if you place your DIY boost leak adaptor at the inlet bend like in the following pic, - what do you have to cap off so you dont get false boost leak readings i.e. PCV hoses? - and surely the test wont work if the throttle butterfly is open (becasue valves open in engine etc) and if its shut i bet its not a tight seal! - and what if the boost leak is actually somewhere in the manifold anyways?? has anyone actually done this test or one like it??