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Old 10-19-2013, 12:04 PM   #1
cowboy_Rob
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Car is an 03 wrx with an 04 sti engine. Fp red, dw1000s, aps fmic, crower 272s, bc springs/retainers, Perrin rails, ewg, group n mounts agency power pitch mount, lots more stuff. Running carberry speed density tune with gm temp sensor in ic pipe.

Engine is a new Outfront block with my used Manley slugs, stock rods with arps, new heat treated crank, stock sti heads

With my original wrx knock sensor it was reading knock from 6k up. I I loosened it pointed it the right way and retorqued it. Knock from 5500 up.

So far I've removed all the mani heat shields, gutted the rattling muffler, wedged heat wrap between the ewg dump tube and the down pipe in case it was buzzing, the intercooler pipes are bolted solid cant find anything that could be rattling. Did find some info saying engine displacement affects the frequency range the knock sensor needs to be so I got a used sensor from an 05 2.5 turbo. Connector was different so I repinned the connector and installed it. Now it reads full knock from 5k up.

This is all with the ignition timing pulled back so far that with knock correction it's down to 9* of timing from 5k to redline still reading full knock. Af ratio is 11.7 tapering to 10.7 at redline. Not sure if the richness is in the tune or due to the timing being pulled. It's at 12.3 under boost earlier in the rpm band before it starts pulling timing

Me and my tuner are running out of ideas. We're fairly sure it's false knock since it doesn't respond to pulling timing but what else could be causing it if nothing is rattling

This is all at wastegate boost so 10-11 psi. That was the first thing we tried was just lowering the boost
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Last edited by cowboy_Rob; 10-19-2013 at 01:09 PM.
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Old 10-19-2013, 01:09 PM   #2
Concillian
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Need det cans at this point.
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Old 10-19-2013, 01:13 PM   #3
cowboy_Rob
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Details on det cans? I've heard of them for cars without knock sensors but how can they help if we already have a knock sensor and know we have "noise"

Any input on mechanical vs electronic ones? I found some videos of how the engine was supposed to sound with/without knock on some Evo videos and Honda videos anybody have a subie version

Last edited by cowboy_Rob; 10-19-2013 at 04:51 PM.
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Old 10-20-2013, 10:15 PM   #4
Concillian
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It helps because you can listen to them and differentiate between regular noise and det. A knock sensor will trigger on any noise level in the bandwidth it's designed for. A tuner listening can differentiate between a noisy engine and actual knock.

This has to be coupled with de-tuning the knock sensitivity in the ROM so that the engine doesn't pull out timing / add fuel when it doesn't need to.

I think Harbor Freight carries an electronic mechanics stethoscope that would work. Just have to rig a way to get it attached to the block near the knock sensor.
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Old 11-01-2013, 07:51 PM   #5
cowboy_Rob
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Ok I made some det cans. Stethoscope and hose to a cable lug booted with the knock sensor. You can hear a slight tick idling and a bit louder at higher rpm but definitely engine speed and its doing this free revving it in my garage so its definitely not detonation.

Now what how can I chase this down? I'm inclined to think the noise is probably valvetrain since the shortblock is fairly mild. Anybody having these issues with crower cams and Brian crower springs/retainers? I set the valve lash at the crower spec I can look in my papers at work what it was.

I've got like 3500 miles on the rebuild so I would expect it to have gotten louder by now if it were something bottom end related.

Just changed the oil a couple days ago and it's nice and clean too. Rotella t6 5w40
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Old 11-01-2013, 10:47 PM   #6
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Quote:
Originally Posted by cowboy_Rob View Post
Ok I made some det cans. Stethoscope and hose to a cable lug booted with the knock sensor. You can hear a slight tick idling and a bit louder at higher rpm but definitely engine speed and its doing this free revving it in my garage so its definitely not detonation.

Now what how can I chase this down? I'm inclined to think the noise is probably valvetrain since the shortblock is fairly mild. Anybody having these issues with crower cams and Brian crower springs/retainers? I set the valve lash at the crower spec I can look in my papers at work what it was.

I've got like 3500 miles on the rebuild so I would expect it to have gotten louder by now if it were something bottom end related.

Just changed the oil a couple days ago and it's nice and clean too. Rotella t6 5w40
if your 100% its all phantom knock you can turn down the knock sensor sensitivity but make sure you know what you doing as it can be dangerous
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Old 11-02-2013, 12:48 PM   #7
blubug_768
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How do you change knock sensitivity on carberry, I'm pretty much having the same problem as op only its not consistent, some pulls I'll get knock sometimes nothing.
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Old 11-04-2013, 12:39 PM   #8
cowboy_Rob
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Quote:
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How do you change knock sensitivity on carberry, I'm pretty much having the same problem as op only its not consistent, some pulls I'll get knock sometimes nothing.
From what ive found its not adjustable yet. You have to add a filter to the wiring and electrically reduce the signal.
However if yours in inconsistent it's probably actual knock or something rattling that can be fixed. Mine does it every pull every time
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Old 11-04-2013, 04:10 PM   #9
Concillian
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You can't change sensitivity on knock correction in Carberry, but you can change loads and RPM where it will correct for knock. If it's not retarding in the midrange, then cut off the high RPMs early. If it's phantom knock at cruising loads, then increase the load triggers.

There's three knock settings you have to change. Fine, Feedback, and Rough. The settings in RR are pretty self-explanatory.
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Old 11-13-2013, 12:06 PM   #10
WRick
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What version of carberry are you using ???
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Old 11-17-2013, 09:46 AM   #11
cowboy_Rob
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What version of carberry are you using ???
I'm not sure, i'd have to check with Steve. Currently were tuning it with detcans with the knock correction disabled over 5300 rpm andjust taking it slow on adding timing back in. Nice to have the thing finally starting to make some power again
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Old 11-18-2013, 08:55 AM   #12
WRick
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Yeah, check with steve. Some older versions of carberry have a different knock sensitivity that can throw some ghost knock around.
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Old 01-16-2014, 09:32 PM   #13
cowboy_Rob
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It was getting worse where it would read knock down as low as 3k but it seems like I might've found the problem. I took the belts off to check the timing belt tensioner and noticed it was quieter. My alternator pulley is too small and my belt was a little long so the adjuster was maxed out and wearing into the side of the adjuster slot. And the top bolt for the ac belt tensioner bracket was half stripped. Once I fixed those problems I've taken a couple logs with no knock and I have another rom to flash on and reenable knock correction that we had disabled over 5k but I'm hoping I'm good to go
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