So, starting a new thread similar to one I started a while ago, but more of a mod and not a fix now.

Long story short, I had accidentally placed the 'T' restrictor inline with the manifold FPR line, when it should have been on the boost gauge I was installing.

The result was a similar effect to the 'VGS' mod, unless I'm going crazy.

At any rate, to fix the buzzing in my boost gauge, I rerouted the lines. The smoothness seemed to go away, but wasn't sure (was adapting to new cam).

Months later (and still living with a tiny bit of buzzing around 14 psi), I bought a 3/16" restrictor from a local parts store to place inline with the boost gauge for even more restriction (hoping to get rid of all buzzing). Seemed to work OK.

Just for the heck of it, I rerouted the line to place one restrictor on the FPR line again. Sure enough, the smoothness returned.

I am doing something really bad? Does anybody else want to try this mod and see if they have a similar experience? I swear it seems to reduce my yoyo as well.

Speculating that the oscillating boost/vacuum in the manifold is causing some issues with the FPR.

 

not trying to sound too dumb, but whats FPR?

 

Oh sorry, Fuel Pressure Regulator.

 

i dont want to try the mod, sorry :P im not sure messing with that regulator is a good idea... you wouldnt want to starve your engine of fuel by accident or something. it should also have no effect on the actual BPV opening / closing, which is of course regulating your boost in the engine.

however, interesting piece of information (possibly): i have the Stewart Warner Cooper S gauge setup, which includes a boost gauge. that setup Does use a T splitter with built in restrictor, to properly calibrate the boost gauge (the gauge doesnt need calibration, but, it wouldnt read correctly without said restrictor in the T).

what brand of boost gauge you using? whats your pulley? and, strangest of all, what is this "buzzing" you speak of?

alternatively, have you considered the buzzing is the actual gauge itself? i only say so, bc i have another gauge cluster installed on my dash now (oil gauges) and they too "buzz" at different RPMs while driving. (altho my buzzing is more of a metal "tinkling" sound). at any rate, its the gauges internals themselves that are causing the noise! think there is any chance YOUR gauges are doing similar? where / how are they installed?

 

I have the oem gauge cluster installed by myself with the help of a local garage.

The buzzing is coming from the boost gauge. Was much more pronounced when the restrictor was not on the gauge line. I did a quick search here on NAM that resulted in the probably cause and hence the fix to return the gauge line onto the restrictor portion of the T.

However, the boost and vac readings seem correct either way I go (hard to confirm during dynamic operation, but static was fine as compared with an OBDII reader).

Still getting a feel for how the car runs now. Yo-yo is still there, no surprise really. The car does still feel a little smoother down low. I think I am noticing that the engine breaking is not as pronounced when down shifting. I mean, not when pushing in the clutch, but when snapping up to rpm when engaging the lower gear.