Is your ‘check engine light‘ flashing on your dashboard and does the engine’s power suddenly feels reduced?
Then your car engine might have put itself into Limp-Mode and the issue should be fixed as fast as possible. Boost leaks can damage your turbocharger and your engine, which may result in even higher repair costs.
In this article, you will get all the information on how to detect and repair a boost leak and finally get your car’s full performance back. Let’s begin!
Boost Leak Information
A boost leak is a type of air leak that happens in the intake path just before the engine cylinders. It is basically a loose clamp that cannot handle the pressure from the boost.
Engines that have turbo are more prone to a boost/intake leak compared to non-turbo engines, because of the added numbers of pipes and hoses joining the turbo with the engine equipment and the pressure that a turbo gives. These hoses and pipes are directly exposed to the heat inside an engine bay, which can cause cracks in them and lead to leaks.
Sometimes, leaks in a pipe can happen due to a loose engine mount, which can twist a pipe simply with torque. Although loss of power is not harmful – except if you are in a race – it can become harmful if neglected for a long time.
Ignoring a boost leak will eventually reduce your turbo’s life and in turn the car engine’s life. Understanding the workings of a turbo is easy as there are two components at work; fuel and air. The car’s engine works on a mixture of fuel and air.
The ECU determines the ratio of fuel to air; however, if there is leakage of air along the way, the ratio is incorrectly calculated causing your car’s turbo to work harder than usual. Diesel engines are accommodating in this regard as they are more tolerant of a high fuel to air ratio. However, petrol engines are sensitive, therefore a boost leak inspection is necessary for your car’s optimal performance.
Signs of a Boost Leak
A boost leak can result in a lot of different symptoms. There are a few of them that are worth looking closer at to identify a boost leak. Here are the most common symptoms:
1. Slow Spool
The turbo works by increasing the amount of air and fuel that can be fit into a cylinder; thus, increasing horsepower and performance. However, before the turbo ‘kicks in’, it’s turbine needs to spin very fast. Until that happens, the turbo does not play a role in boosting the car.
This issue, usually called the turbo lag, is when the turbo spools air and fuel to send into the cylinder. If this process is slower than usual, you are experiencing a boost leak. The concept is simple; due to a leak, it takes more time for a turbo to spin at maximum capacity.
2. Loss of Power
While you are accelerating, the turbo is giving a boost to the engine, motivating it to perform faster and better. If there is a boost leak, you will feel a sudden loss of power during acceleration.
3. Check Engine Light
If you have a boost leak on your car, you will most likely get a flashing check engine light on your dashboard. If your check engine light is flashing, the best method is to read the trouble codes with an OBD Scanner.
4. Poor Idling
This only holds true if you have a car with a mass air flow sensor or MAS/MAF. The MAF senses the amount of air leaving the turbo and entering the engine. If there is a boost leak – which usually happens in the MAF area – your car will have problems idling perfectly. It might stall, and close down as a result of the leak.
5. Inconsistent Timing
Your engine tuning will go awry as soon as you have a boost leak. Therefore, any inconsistent sound in your engine is basically due to a boost leak.
6. Excess Smoke from the Exhaust
The inconsistent working of a turbo will disturb the process inside the engine cylinders. More than the usual amount of fuel will be used and you will see more than the usual amount of smoke coming out of your exhaust.
7. Poor Economy
This might not be distinguishable very easily but if you keep an eye on your car’s average fuel consumption you will catch a boost leak easily. If the car is consuming more fuel than it should, you have a problem. A boost leak test can prove to be helpful in such situations.
|Boost leak symptoms||Low acceleration
Check engine light
Black smoke from exhaust on acceleration
Poor fuel economy
|Faulty Boost pressure pipes
Faulty Intake Plenum
Faulty vacuum hoses
|Replace/Repair the boost leak|
How to Find a Boost Leak
The easiest way to find a boost leak is to use an EVAP smoke machine but you can also use compressed air or in some rare cases – visually inspect the boost pipes and hoses. Here are some tips on how to find a boost leak.
1. Check Clamps & Couplers
A boost leak can happen where there are clamps, so it is natural to look for leaks in all the couplers and clamps connecting the turbo to the engine. Maybe a clamp was not properly tightened or it was left loose after you made the previous modification to your turbocharger.
To start your inspection, first take a look at the compressor housing, move towards the vacuum lines next, and work your way to the wastegate controller. Check all the clamps on the way and ensure they are tight and in place and also check for any scratches or cuts to the housing.
2. Use a Boost Leak Tester/compressed air
Still couldn’t find out anything? No worries, some brilliant minds have invented a device called the boost leak tester. This device does exactly what it is supposed to; it tests leaks for you, so you don’t have to. This is a great tool for anybody who is not experienced in car work and also for those of you who don’t want to spend money taking their car to the nearest mechanical workshop. Therefore, if you can afford one, you can save some precious time.
Using a boost leak tester, you don’t need to start up the car or need to charge up the turbo. In fact, the machine does all the work by itself by pressurizing the system just like a turbo spool. All you need to do is remove the turbo inlet and attach the tester in its place. Alternatively, attach an air compressor to the system and watch the machine build pressure. Now, simply listen for air leakages and mark them.
Boost leak testers are a surprisingly cheap and a necessary tool for every turbo car owner.
You can also go to a mechanic workshop and use their boost leak tester for a small penny.
Check out the adapter at Amazon here Torque Solution TS-BLT-BILLET Boost Leak Tester Universal and make sure it fit your pipes. The only thing you need for this tool is compressed air.
You can also use an EVAP smoke machine to find any boost leaks easily.
Repairing a Boost Leak
Once you have found the leak, it is time to patch it up. As we have learned from the information above, leaks are usually found in untightened clamps or couplers. Start off by tightening them up and then checking again until you find all the leakages. If you need help, hire a mechanic but the thing about mechanics is they charge quite a high price for such easy work. Keep in mind a bill of about $100, give or take, if you choose to go for a mechainic.
Hello I’m Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I’m specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I’m here to give you answers to all your automotive questions and I hope that you enjoy our content.