Fluidampr helping with false knock?

[Pleides]

Hey all, a potential part buy I'm considering is the Fluidampr crank pulley for our GTs. I've heard from a few people that it can help prevent false knock. Like many others, I've got a stutter at around 2K RPM that occurs mostly when driving the car cold, but often can occur when warmed up or hot-started as well. The engine is nearly new and has done this with it's previous engine and zillions of different mods from the fuel system to the valvetrain components. The usual fixes (tuning, vacuum line relocation, etc) have not fixed this problem for me and I'm fairly certain some sort of engine/engine bay noise triggers the knock sensor to aggressively pull timing quite sharply at that RPM. 

 

I'm wondering if the pulley has helped others with this stutter or other false knocks that had no other solutions otherwise? Also wondering if somebody has any before and after footage of their car on a dyno or the like before and after installing the Fluidampr pulley. It's an expensive item and I'm wondering if it's worth it for a stock shortblock car. If it solves that never ending stutter then I'll pony up.

[Underdog]

I went from the Grimmspeed LWFW to the Fluidampr pulley. My car did not have the stutter/false knock issue but did have a slight pulsing at low-load/steady-rpm cruise that I was hoping it would smooth out, and it did to some effect, although I’ve since discovered the cause elsewhere in the system. The main difference I noticed was a smoother idle (in terms of NVH) and the improved flywheel effect at take-off and in between shifts. I suppose the lessened NVH could contribute to fewer perceived knock events but have nothing to back that up. 

If you go with the Fluidampr you will need to dremel the timing belt cover to make some clearance. Not a big deal, just fyi. 

[Enlight]

1 hour ago, Underdog said:

My car did not have the stutter/false knock issue but did have a slight pulsing at low-load/steady-rpm cruise that I was hoping it would smooth out, and it did to some effect, although I’ve since discovered the cause elsewhere in the system.

What ended up being the source of your pulsation? Mine had the same problem but I'm hoping my next tune will take care of that.

FWIW, I also got the Fluidampr and noticed much smoother idling as well, but I don't think it would solve a stutter issue.

[Underdog]

3 minutes ago, Enlight said:

What ended up being the source of your pulsation? Mine had the same problem but I'm hoping my next tune will take care of that.

FWIW, I also got the Fluidampr and noticed much smoother idling as well, but I don't think it would solve a stutter issue.

I'm 99% sure it's due to the front O2 sensor being relocated to the downpipe bellmouth on the twinscroll setup. It appears to be a common issue on USDM cars running twinscroll setups (which is not a large pool to begin with, so take that with a grain of salt) - the last tuner I worked with explained that our ECU lacks the delay parameter to deal with the altered location. It's not definitive but I've turned over pretty much every other stone.

[NORULZleggy]

You should have already bought it. this is one thing I tell everyone to buy. My car did not have a stutter or anything else, but the car is smooth, and runs great. Buy it.

[KZJonny]

Definitely improved smoothness at idle for me. I still haven't installed my SMFW, so I get some shudder/judder with low speed shifts still, but less with the Fluidampr.

Installed with too many other things to be able to be able to say what specifically it was that caused the improvements, but I'm pretty happy in any case with the results.

FWIW I do not find I have the stutter at the 2500 RPM point so many speak of, but I may not have before all the modding started....

 

It is a nice quality piece in any case, and I appreciate the added layer of smooth running and idle. I've also seen them on quite a few higher output engine builds on YT done by people whose knowledge and skill are far greater than mine. Interestingly/oddly they aren't always mentioned, but I see them on engines nonetheless... Maybe they either go under the radar, or it's something to do with not mentioning products who don't support channels etc... If the latter, then it's noteworthy that people use them a bunch without being sponsored by them..... tho that is just a theory.

Edited January 27, 2023 by KZJonny

[Pleides]

Thanks for all the replies. My stutter is some sort of knock event triggered by something nobody who has worked on the car (including myself) has been able to track down. During tuning the car doesn't seem to exhibit the issue, so maybe something happens when I go over neighborhood bumps or whatever that the ECU reacts to. It generally doesn't happen if I let the car warm up by idling it during cold starts. Part of me thinks it has something to do with the fact the car has TGV deletes. 

 

Anyways, thanks for the information @all. I'll be waiting for a sale on the part or the crank pulley to be in slightly worse shape or maybe a few too many zeroes in my bank account (ha) before buying one. Again, if anybody has any before and after dyno results with one then that would also be appreciated.

Edited January 28, 2023 by Pleides

[Pleides]

13 hours ago, Underdog said:

I'm 99% sure it's due to the front O2 sensor being relocated to the downpipe bellmouth on the twinscroll setup. It appears to be a common issue on USDM cars running twinscroll setups (which is not a large pool to begin with, so take that with a grain of salt) - the last tuner I worked with explained that our ECU lacks the delay parameter to deal with the altered location. It's not definitive but I've turned over pretty much every other stone.

Sounds like someone needs a standalone

[Underdog]

9 hours ago, Pleides said:

During tuning the car doesn't seem to exhibit the issue, so maybe something happens when I go over neighborhood bumps or whatever that the ECU reacts to. It generally doesn't happen if I let the car warm up by idling it during cold starts.

That's a pretty solid clue right there - if it only happens when the car is cold and moving. I'm assuming you've checked the sensor itself? Tightened it down, looked at the wiring, etc.?

[m sprank]

Cant say I ever installed one to reduce false knock. But I ran them on my own cars.  Not as many customers were willing to spend the money, but they are worth it. Especially on a Subaru.

[Pleides]

5 hours ago, Underdog said:

That's a pretty solid clue right there - if it only happens when the car is cold and moving. I'm assuming you've checked the sensor itself? Tightened it down, looked at the wiring, etc.?

Yeah, I mean the whole engine was removed from the car two years ago so barring replacement of the sensor it all looks and performs like it should. Given it has no issues with tuning on a dyno I would assume Surgeline would have let me know that something was wrong with it if it had issues. I suppose I could replace it but I strongly suspect it works fine.

[m sprank]

I picked up false knock from a failing front sway bar endlink. 

 

That was my own car and I posted about it. But the thread was probably from 2009, lol. 

[Pleides]

7 minutes ago, m sprank said:

I picked up false knock from a failing front sway bar endlink. 

 

That was my own car and I posted about it. But the thread was probably from 2009, lol. 

This has been an issue since I purchased the car. I've replaced every single component on this car by now, including OEM worn out endlinks with Kartboy ones, ha! The car has 240K on it and nearly nothing it came with when I bought it in 2018 with 200K.

The previous owner told me that the hesitation started as soon as he modified and tuned the car. He did TGV deletes and a turboback exhaust as well as a Perrin inlet. I've had it tuned by two other shops and neither has been able to trace the source of the stutter, so I'm kind of just stuck with it. I'll see if I can get an eyeball on the sensor but my assumption is that the PNW climate has been relatively kind to it and that it won't have any cracks or issues like that. 

Edited January 28, 2023 by Pleides

[m sprank]

2000rpm and only when cold?  Only when driving on road not rollers?  Something that heats up, expands and quiets?  Subaru (especially turbo cars) knock sensors are very finicky about postion and torque.  Otherwise they are just a microphone picking up noises.  Remove hood, have friend lay across engine with stethoscope over knock sensor while you drive and log.  Hand signals to communicate noises and knock counts.   Shit we used to do to troubleshoot, lol. 

Edited January 28, 2023 by m sprank

[m sprank]

When standing at front of car looking towards rear sensor wire tail ahould be at about the 10 o'clock position.  I cant recall torque spec, but want to say around 12-15lbs. Maybe Rick can chime in, otherwise its the FSM.  Honestly, finicky suckers. 

[Pleides]

53 minutes ago, m sprank said:

2000rpm and only when cold?  Only when driving on road not rollers?  Something that heats up, expands and quiets?  Subaru (especially turbo cars) knock sensors are very finicky about postion and torque.  Otherwise they are just a microphone picking up noises.  Remove hood, have friend lay across engine with stethoscope over knock sensor while you drive and log.  Hand signals to communicate noises and knock counts.   Shit we used to do to troubleshoot, lol. 

Part of me wonders why I never asked my tuner to remove the high cold start idle. I have an aftermarket cat but it would get up to temp just driving. I'm willing to bet it would solve my issues. The knock sensor can pick up valvetrain noise from a cold start, right? 

 

I'm currently holed up at home on a very cold day (snow is potentially in the forecast for my neck of the woods) but I'll see if I can get my car in the shop at work tomorrow and check out the knock sensor. I can't remember - are the intercooler gaskets single-use? Been a minute since I removed it to do anything.

[m sprank]

Most intercooler gaskets are single use. There was a silicone/steel version that may or may not still be available. 

 

Yes, knock sensor hears the valve train. If you hit the trans housing with a wrench the knock sensor picks it up. 

 

Honestly never played with cold start high idle in anything other than a track car that I recall.   Easy enough to test and revert if other issues arrise. 

Edited January 28, 2023 by m sprank

[KZJonny]

https://www.holley.com/products/gaskets/other_gaskets/parts/738G
 

It’s actually silicon, not rubber…

Or at least it felt that way to me. Great product in any event. Sealed up tight for me, despite my turbo being ever so slightly out of place. (My fault, and a problem for another day.)

[Underdog]

Knock Sensor P/N: 22060AA111

Knock Sensor Installation:

[BoozeRS05]

A Fluidampr pulley is very high on my list of future purchases. Been trying to wait for a good deal or a sale bc cost seems high to me, but everything I’ve read is great.

[Infosecdad]

I installed one on my white wagon a few years ago, it was definitely noticeable in smoothing the engine out. 

Highly recommend, especially if you can get it for a discount.

[m sprank]

2 hours ago, Underdog said:

Knock Sensor P/N: 22060AA111

Knock Sensor Installation:

Thanks Rick!  I was close. 

[shralp]

Similar experience, bought a used Fluidampr from Sgt. Gator a few months back since he had an extra laying around from his various race car builds over the years. Definitely smoother at idle and in general. Didn’t put it in to solve any issues per se but the price was right and I wanted to get away from the OEM one in my track car since it’s 18yrs old now and it gets driven hard.

[BoozeRS05]

Been spending way too much money lately, but found a good deal on a used one of these today. Not sure if it’ll sit on my bench until my motor refresh or maybe I’ll throw it on sooner. 

[Pleides]

On 2/5/2023 at 4:56 PM, BoozeRS05 said:

Been spending way too much money lately, but found a good deal on a used one of these today. Not sure if it’ll sit on my bench until my motor refresh or maybe I’ll throw it on sooner. 

Any updates on your experience with it yet?