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Hey again everyone, I was hoping somebody might be able to help me sort out an issue that I'm experiencing after fitting a new HKS EVC-S boost controller on my S2 Stagea RS4S.

When the controller is off the boost comes on at wastegate spring pressure (which on my Stagea is around 5-6PSI) so without the dual-stage in place it sits on the lowest possible pressure, thats not the issue however when I turn the boost controller unit on and dial in enough boost pressure for around 9PSI I can hear something (which I presume) like the HKS solenoid clicking quite a fair bit. There is no clicking when the unit is off however.

The boost is stable all the way to 9PSI with no overshooting or surging and no hesitation from the engine. So its defiantly something along the lines of the boost controller unit when its on.

Could anybody throw some suggestions at why this might be the case? Have I got the unit set up incorrectly in someway? After searching google a bit I've found theres plenty of info on clicking solenoids but they seem isolated to Greddy and Blitz units, and even then its not conclusive.

I was maybe thinking the boost setting I've got may be asking to much from the solenoid too early? Full boost at 9PSI comes on around 3500RPM.

Hi I had the same problem with my greddy unit. The solution is very simple and i presume it will be the same for yours. You need to put a rubber grommet between the solenoid and the car. The solenoid will still click the rubber just stops the noise traveling through the car. I hope this helps.

Thanks for the suggestion never thought it might be something as simple as dampening the vibration of the unit itself so fingers crossed that might be the cause. I'll hunt down a rubber washer today and report back if the clicking gets softer.

  • 3 weeks later...

i just installed my hks evc-s got the same issue with clicking... at first it wouldn't do it but eventually i heard it like 2 days later... very very odd...

i also have a rubber washer between the unit and my chassis, but clicking is still loud as fk lol

so i think if the problem lies within the over boost function i may just tune it using the over boost a bit more (currently its set to 0 whilst using the offset to control the psi)

its not a problem, the solenoid will click when its 'adjusting' the amount of air passing. your factory ones do the same thing, they are just quieter, and probably slower (i cant remember the frequency, 10Hz?) but aftermarket ones are generally faster and make more noise, but they do a better job. like a bigger exhaust, noisy, but more power :P

isn't it open until 4500 then it starts pulsing?

open = wastegate spring pressure

pulsing = higher boost levels

my rs4s runs 7 psi with the solenoid off and 10 with it permanently grounded

if it was closed below 4500, it'd be freeboosting. it just pulses at different rate after 4500.

WRONG . the line to the solenoid is teed into the reference line to the waste gate . closed = waste gate pressure. open it bleeds off as much air as the factory restrictor will allow.

why do you think bypassing the solenoid is the same as having it permenantly earthed

thats right, factory solenoids work in parallel to the turbo, aftermarket ones generally are in series with the wastegate actuator line.

why? because if it fails, it will most likely lock in a closed position and the car wont overboost and die

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