Curious intermittent vibes

Okay, so gen juan with 92k on the clock. basic bolt-on's and stock k04. Running with the DM pmm and Tmm with a jbr dogbone 88. even before the mounts I get an occasional crazzzy vibe. If i blip the throttle it stops. this only happens when downshifting to slow down or cruising in 3rd or 4th. I've watched for knock retard during this and nada, not even a little. Nothing appears to be mechanical with the motor. yet i do occasinaly get a clunk like the motor is twisting. This weekend I loosened the mounts and re torqued all three per their specs. No change.

Anything else i should look for????

 

Check to see if any exhaust pipes are making contact.

 

Ill do that tonight. seriously doubt that i would feel that heavy of a vibe from that. I feel it in my gut when it happens

 

Alright so nothing is rubbing underneath. I know the mounts added some vibes but this is one that isnt always there. never an knock retard during the episode. It almost feels like a stumble or a mild misfire.

 

Might be worth logging while driving and try to capture, if tuning related. Could be maybe a loose heat shield or something. I remember someone finding their heat shield on the downpipe/manifold or somewhere was loose and was the cause for a long term headache.

 

That's the thing, I've been logging for freak, and it usually happens on decel and ill let it keep logging. it definitely feels weird but ill see if i can make it do it on a log and post here

 

I get a slight vibe between 3200-2800 on decel in 3-5th gears from my Damond TMM. It doesn't always happen, but it just started after I installed the mount. It's almost like the AC kicking in.

 

Mine is more than slight.lol
But i think that may be where its coming from. I'm changing out the plugs tonight since they have 40k on them. Ive also noticed some slop when i let off the throttle. I'll keep digging. Didnt happen last night so no log yet

 

Check the mounts? Maybe one is loose or the RMM might be damaged. I always had some vibes on neg. acceleration around 3k rpms and with the DM mounts it has gotten more noticeable. If it is not mechanical then hopefully the logs will find it.

 

I've always had vibes on decel. I just crank up the panda porn and enjoy.

crapatalk, yes it sucks for free.

 

Over the weekend I basically removed the pmm, and rear mount. to re-torque as if i was installing them new. i need to do the tmm this weekend just to rule it out. the vibes normally don't bother me, but this feels quite a bit different than heavy vibes. If i just lightly tap the gas and release it goes away. that seems odd to me.

 

I've literally got the same thing happening with my car. I've got the DMM trilogy and the same thing happens. It happend with my JBR trilogy too. I've thought it was something wrong with the motor or the vvt, but everything looks good from logs and my monitoring with the ap.

crapatalk, yes it sucks for free.

 

Modal analysis ftw. If your logs check out that is.

 

here is a wot log with some decel with vibes. you can see where i bliped the throttle to send it away.

 

Any resolution on this? I have the same problem and im hoping its not the VVT. Id look at the log but im on my work computer at the moment.

 

Not yet, i need to look at the transmission mount, and the AC. Its more pronounced with the ac on but, i think that may just be amplifying it. also need to check the rmm bushing block side

 

I find it wierd that it happens at like 3200rpm the dot everytime it does it and stops at about 2600. It seems like something more than just mounts but vibes from mounts can be wierd like that. Im going to check the balance shaft next time i work on my car.

 

RPM wise it varies, but only on decel, bliping the throttle will make it stop?? which is weird to me.

 

For me blipping the throttle or a quick clutch in-out doesnt always stop it.

 

My juan did this. I could actually get it to happen at ~75 on the interstate, a random, vicious vibration that would go away with a little throttle or slowing down a bit. Same RPM range you're talking about. Never figured out what it was and was never concerned, I think it was just a stack up of harmonic modes that resonated through the frame rails. My pu doesn't do it.