Why is the supercharger boost pressure too low?
2 Answers
Reasons for low supercharger pressure include air filter blockage, supercharger damage, and excessive oil deposits in the air passage. Air filter blockage: When the turbocharger's air filter is blocked, it increases suction loss, resulting in insufficient boost pressure. Typically, the air filter should be thoroughly cleaned after 1,500 to 3,000 hours of use. Supercharger damage: For externally supported superchargers, if the air seal device on the back of the compressor is damaged, a large amount of air will leak from the back into the intermediate housing and be discharged into the atmosphere along with the exhaust gas from the turbine, leading to a drop in boost pressure. Excessive oil deposits in the air passage: If there is excessive oil buildup in the internal air passage of the compressor section, the airflow resistance increases when passing through the heavily soiled passage, causing a reduction in boost pressure.
I've been driving for over twenty years, and low boost pressure is a common issue. A friend's car had the same problem recently—it felt sluggish during acceleration and struggled on inclines. Upon inspection, we found a leak in the intake pipe where the clamp had loosened, causing all the high-pressure gas to escape. If the leak isn't significant, it could be due to excessive carbon buildup on the turbo blades preventing them from spinning, or the exhaust valve sticking and failing to clear the exhaust gases properly. If the intercooler's cooling fins are clogged, the gas won't cool sufficiently, and the density won't increase, rendering it ineffective. The worst-case scenario is a faulty turbocharger itself, with worn bearings or a deformed impeller. For electronic turbos, you also need to check if the sensor signals are correct and whether the control valve is stuck. Each of these possibilities needs to be checked systematically. I recommend starting with the intake pipe—spray some soapy water to see if bubbles form, indicating a leak.
