Rb26 knock readings with power fc

[nimblestix]

Okay im just going to go ahead and start a tech thread so its not over looked by anyone.

I originally made this thread because i was searching for knock sensors or cross reference #'s, but now im going to post as tech in case anyone else has some good info i could use!

OLD THREAD > http://forums.gtrcanada.com/gt-r-tec...ref-knock.html

Last post in old thread :

Yeah today i got a few 80+ and even a 120!!

However my head is slightly built and I've got so much noise coming from it!
Cams, port, manifold port, (& possible springs, not 100%)

My last head was pretty noisy too after I installed pon cams so I'm wondering if maybe I'm picking up knock from the loud a$$ head. Maybe re-shimming the cams might quiet her down.

Weird thing is though, when I went to Tommy, my ign timing was set at 20° retarded, and we could only set to 17° advanced before we maxed out the cas adjustment (all the way right). So maybe its true knock? When we were tuning there was no det sound at all until we upped boost to 17. No hiccups or anything. To be safe he backed off the timing even more after the tune so there shouldn't be any room for error.

During the engine break in When my timing was at 20° retarded and my wastegates unhooked, I didn't register any knock over 30(0 boost) from the few times I checked. So this is why I'm worried because now when its advanced to 17° its showing crazy high knock.

This also makes me think my knock sensors are still functional. Unless they're over sensitive or loose, and now any tiny knock is being shown as a really big knock?

Bear in mind this is an entirely different block, knock sensors and power fc from the block/sensors/pfc I had before. My last build never knocked over 50 on that power fc.

I don't know....

< Posted by me.

I don't want to eat my new engine, and even though my tuner says hes confident its safe, the little blinking red light on my dash scares the hell outa me! Invested far too much to rebuild again...


FYI if it helps, I can register a knock of 60 (power fc) just from revving the engine in neutral....
Also, This engine was built as "Loose Clearance", meant to spin fast and high.
407WHP @ 15.5 PSI < Racing Greeds Dyno.

[bobbo]

I'd have to check mine. Wish I had read this sooner as I was just out with the car.
That being said I decreased the value of when the light comes on (can't remember the value but lower than default setting) and I almost never get any knock.
I'm running peak boost of 1.10 mm/hg. I'll have to check and see what my timing is at. I'll let ya know asap.
Keep in mind I've got a very safe tune on an almost stock car. G-Teck says 317whp.

[christdeyoung]

Update?

[nimblestix]

Update,

i think my knock was coming from a broken peice of valve guide embedded in piston and quench pad.
However the engine that was controlled by this ecu had catastrophically failed due to improper bearing clearances, I'm now using an aem ems v2 on a full new build, and knock readings are mint.

When I tore it apart keeping in mind the really high levels of knock the pfc was showing, there was NO sign of detonation on the pistons.

Another gtrc'r was having issues with high power FC knocks and they were ruled out as being false. One of the best way to tell is with a set of detonation headphones, most of the time you will hear the knock through the headphones before some ecu's will even register.

Brent.

[Skym]

Sometimes something banging against engine, faulty coilpack, just to name a few are causes of higher than normal knock count.

Checking knock via the new (years old but new) knock detecting method (via signal that goes back through sparkplugs, ignition system when there's unstable combustion) will tell you that knock is going to happen before it happens. Some are already using this knock detection setup on OEM ECU's.

[NismoS-tune]

Who had built the engine with bad clearances so people can be aware of them (i had a new engine fail for the same reason)

[nimblestix]

Who had built the engine with bad clearances so people can be aware of them (i had a new engine fail for the same reason)

You and I both used the same builder, remember? We got screwed.

Sent from a galaxy far, far, away.