pressure tester cap

Pressure testing makes everyone happier

Updated: Nov 22, 2021

This might be on the level of psychological advice: get a pressure testing setup.

It’s very hard to catch some leaks without testing. Nearly impossible sometimes.

But a thorough pressure test solves this.

Sometimes a rail isn’t holding the injectors square enough to the manifold (refer to my other blog entry on fuel rail options if you run into this), sometimes there’s a hairline split in a coupling or a pipe or the manifold or the maf. This stuff happens. Sometimes it happens with brand new parts. It’s not your fault. Hopefully you have a nice warranty.

With enough leaks, the logs will never look great. The log will be worse with worse leaks. And small leaks may even sneak by unnoticed.

A finished tune incorporating a leak into the tune will only degrade with repair.

Pressure testing can be accomplished in many ways. My go-to option is silicone intakes’s schrader valve capping system.

compression testing cap with schrader valve

compression testing cap with schrader valve

Cap everything. Cap your exhaust. Cap your wastegate (if you have one). Cap breather lines.

Cap everything there is to be capped.

The next hurdle is pressurized air. A traditional air compressor is best. Any size will do. Remember to turn it off so it doesn’t fire up while you’re trying to listen for leaks. You can make do with tire inflators and tires, but it’s rough.

While all leaks have varying levels of problems they present, the most important area for tuning is between the maf and the intake valves. Exhaust and premaf intake leaks can create problems too and this tool and exercise should be used to maintain a leak-free system.

The only people that have no leaks are those that test.

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