
Typically, most un-modified engines will allow 100% atmosphere venting with no problems. However, some combinations of modifications can result in backfiring if high proportion of atmosphere venting is used, in which case the solution is simply to dial back the amount of air vented to atmosphere until the problem is resolved – this is one of the key benefits of the venting bias adjustment feature.Do not be afraid to experiment with the spring and noise settings, no harm will come to the engine if wrong setting is used.Contrary to popular belief, the spring pre-load DOES NOT need to be adjusted to suit different boost pressure. The Respons TMS will stay shut under full throttle conditions regardless of boost pressure or spring pre-load. Rather, the spring pre-load affects how easily the valve opens when you lift the throttle, and how long it stays open when it vents. Adjusting the spring is a simple matter of ensuring the valve opens enough to release the air, but not long enough to cause idling problems. The guide below will walk you through the steps involved.The screw in the centre of the head is the spring adjuster. Use the supplied 5mm hex key to make adjustments. The softest spring setting is achieved when the top of the adjustment screw is 3mm above the head of the valve (shown opposite). Do not set the screw more than 3mm above the head.Set the spring to the softest setting, and move the noise adjusting ring to at least 50% atmosphere venting so you can see the piston through the trumpetStart the car and let it warm up to normal operating temperature. Make sure the A/C is offLook at the piston through the trumpet. If it is hovering open, wind the adjustment screw in the “+” direction until the piston closes fully. If it is already closed, proceed to the next stepGive the engine a good hard rev – if your car has an electronic throttle, you will need a helper to do this whilst you watch the piston. The piston should lift slightly and vent, then close slowly and smoothly. The harder you stab the throttle, the further the piston will open (note: it will only open fully when driving, as the turbo does not generate boost until the engine is under load). WARNING: Keep your face away from the trumpet opening when revving the engine. View the piston from an angle away from the blast of airIf the piston stays open too long, and is not closed when the revs drop back to idle, the engine will “stumble”. If this happens, wind the adjustment screw in the “+” direction one turn at a time until the engine returns smoothly to idle after revvingAdjusting the sPRING PRELOAD