Thread: Detonation or Timing Chain? (Dyno Video)

I think smoothing 0 will show ridges on any graph. Oddly enough it got rid of the sharp 'bump' at the very end of the graph. here ya go:



Ya that's what makes me think it's the chain as it's so loud. You can hear the chain rattling at idle.

if the timing chain is the issue then replace the timing chain tensioner. I would also remove the guide cover that sits over the chain between the cams.

Nah, it doesnt sound like detonation. Detonation is more like a rocks in a can type sound and you would definitely hear it. It almost sounds the same pitch tone as your bov when it released almost like the bov may be fluttering open and leaking boost.

Doesnt sound like chain either. Not likely to have that type of sound at high revs under load. Chain is much more high pitched as well when its hitting the guide and so on.

If your plugs looked fine without any pitting or anything and a/f was good across the board during the dyno, im gonna say its the bov leaking.

I think it definitely was a metallic sound..listen to the clip again, are we listening to the same sounds/stuff? There's supposedly a few more videos of the other 2 runs my friend shot, so hopefully I can get those up as well for more references. You can really start to hear it around :06. The BoV is a crushed 1g DSM. It could be the boost leak around the compressor housing -- we've taken it apart two times to try and seal that mofo up but with no luck. Still leaks under boost leak test. I really don't think the BoV is leaking.

There's two things that changed since last dyno: JWT Tune and Timing Chain Tensioner. Maybe a 3rd which was attempting to seal the compressor housing.

Car WAS running lean. The new JWT tune was running lean, but I didn't realize how lean until the day of the dyno. AFR was About 12.1-12.2 I'm in contact w/JWT to get a richer tune. I knew it was running somewhat lean, but I've always seen it around 11.7 in the past on my wideband(showed 12.1-12.2 during pulls on dyno day).



Guide cover has been gone for over a year. I've changed the tensioner once before a few months ago, only to discover it made my issue worse. I think that's because my W10 came w/the N1 type tensioner and the new DE one I put in was too short for the already messed up timing chain. What needs to happen is to replace the entire timing chain and the two timing chain guides I will be putting the W10 one back in as soon as I get time.

-G

just get yourself a new style tensioner from Greg and be done with it if you feel its the chain. It just really sounded like the bov tone. If you listen to the sound its the same pitch as when the bov goes off when he let off. 1G dsm bovs are notorious for leaking even when crushed and also makes them flutter like that.

Again its hard to tell on the vid but we are listening to the same sounds. Ive heard detonation up close and that definitely doesnt sound like it. And detonation is more likely to occur at peak torque with the t2 turbos. Your a/f is slightly on the leaner side but not enough to cause issues unless your timing is too much but for jwt i doubt thats the case. Not likely to have that sound all the way through the upper rpm band.

I tried the new DE tensioner from Greg(in the car now and during dyno runs), but it made the chain stretch issue worse. I discovered that my W10 DET came w/the N1 tensioner and I think the new DE one is too short. I'm putting the old N1 style one back in when I get time, but the chain is still loose and base 15* timing is strange. I've made a few posts in the past regarding my timing oddities.

UPDATE: Final 2 videos have been uploaded to first post

-G

^agreed. Mine is NA, but I had detonation and I believe the chain has rattled since I bought the car and both happen under lower rpm; such as your in a high gear and open the throttle completely.

I can't really hear the noise because of crappy speakers, but do you think there's a chance your cam oil rails are partially clogged? I have a noise that sounds like what you are describing and I was told it could be that.

I also have replaced my TCT with the new one and I thought it made my noise louder too. Hmmmmm are other people having this issue too?

I really doubt it's the BOV(I wish it was). The sound in person is slightly more detailed than in the video and the sound I heard was very metallic like metal on metal sound. If there's any leak, it'd be by the compressor housing because that's a known leak during a leak test.

If you don't think it's detonation than it must be the chain hitting something or some other strangeness.

-G

if you dont have the upper guide then take your valve cover off and see if its hitting the valve cover. You would have to have some serious stretch to hit the valve cover but i have seen it but with the upgraded tensioner i highly doubt it. The new tensioner is pretty strong and is plenty long enough that even with stretch should have no issues tensioning your chain properly.

Again id have to hear it in person to be sure. The sound is too distorted.