VW 1.8T Overboost fixThe over boost solution kit is based on the standard boostvalve kit but uses the boostvalve connected parallel to the N75 to dial out spikes and fix issues with chipped ECU error codes. Eliminates boost spikes and CEL's
Works with chipped ECUs.
Eliminate limp mode and over boost problems.
Fixes turbo Surging.
Easy adjustable boost levels.
This kit includes all the parts you need to eliminate the spikes and lower your car's boost due to ECU over boost.
Overboost solution kit
VW Overboost Solution kit explained
A few basics of the turbo system that applies most conventional turbo systems
You need to understand that a turbocharger's wastegate actuator opens when boost pressure is applied. An open wastegate holds your boost level at that point. A closed wastegate does nothing to regulate pressure. An engine at idle doe not produce boost. When you accelerate or induce a load on the engine, exhaust flow spins the turbine which compresses air to produce boost. By diverting exhaust flow away from the turbine and out the exhaust you regulate the boost pressure. This is the function of the wastegate and its actuator. The wastegate actuator controls the position of the wastegate and how much of the exhaust flow is used to produce boost.
The wastegate actuator is a simple mechanical device. Pressurize the hose leading to it and it begins to push open the wastegate. In the examples below we'll assume the wastegate is fully open at 10psi. As boost reaches 10 psi the waste-gate is open and you're not going to get any more boost. Looking at the first diagram, the path of airflow is show by the red line. (The BoostValve is set to an opening higher than 10 psi so its still closed and not passing boost pressure or bleeding out any air to atmosphere). The VW's N75 boost solenoid is passing all air through it and directly to the wastegate.
So how do we get more boost?
We (well actually Volkswagen's engineers) divert some pressure away from the actuator, so that boost in the engine is actually more than the pressure at the wastegate actuator. As airflow approaches the wastegate actuator a percentage is allowed an alternate path via a boost control solenoid (the N75 in our case). The more air flowing out the solenoid and NOT to the gate, the more boost you get, remember the actuator only works from 0-10psi, once at 10psi, its wide open and your boost isn't going any higher. But, since pressure in the manifold is actually higher your peak boost is higher than 10PSI. The dotted line is the vent exiting the N75 which is routed back into the air intake path before the turbo. (This is a lot like how a bleeder valve works)
But if we chip (ECU flash) the car, and or mod it so that airflow is altered, we now may run into a problem. The N75 may react too slowly and vent off too much boost. Or the computer may be telling it to open too much. If this happens you're going to see a spike or too much peak boost. The actuator needs 10 psi to fully open and hold the boost. If it doesn't get to 10 psi, boost seen in the engine and on your gauge is too high. This is where the BoostValve is used to reduce the spike or hold boost in check. The computer is telling the N75 to open but now we give the airflow a path through the BoostValve as an alternate and direct path to the actuator. By adjusting the BoostValve you control how much air gets to the gate regardless of what the computer is telling the N75. This is what our OverBoost kit does. It takes a BoostValve boost controller and connects so that you get rid of the surges and spikes. Loosening the adjuster on the BoostValve allows more air to flow through the BoostValve and directly to the wastegate actuator, lowing boost. Tighten the BoostValve all the way and its essentially closed and the computer is back in full control of all airflow.