Help! Cars Overboosting

[Benjamin_John93]

Will perform a boost leak test again today and see how it goes.

I decided to check the condition of my spark plugs, they are PFR5G-11 but are gapped at .6mm, would this cause issues?

[Benjamin_John93]

Done a boost leak test, there were no leaks. Took car for a spirited drive and no issues whatsoever, its like it only plays up at night, cooler air maybe? [emoji14]

[silviaz]

On 5/28/2017 at 8:32 PM, GTSBoy said:

Look.  The actuator doesn't matter a shit.  They're both 5 psi items.  What matters is that your boost source is coming from somewhere wrong.  The fact that there is no nipple to connect the boost control to on the intercooler pipework IS THE PROBLEM.  Trace the connection back to where it comes from.  if you cannot see/prove that it is 100% from upstream the throttle, with no solenoid valves or check valves or anything else in the way, then fix it.  This will mean PUTTING A NIPPLE ONTO THE PIPEWORK.  Which would be 100% what the doofus who installed it all should have done, and apparently didn't.

How important is having a nipple? If your car overboosts on X psi (let's say we've boosted the car) if we don't have a nipple but have a boost controller do we run the risk of overboosting? I thought the controller controls that.

[Kinkstaah]

The controller works by measuring your current boost from a boost source. It *has* to be connected to a source of boost.

Without this, it cannot function. You cannot boost a car without this either. It is a requirement to have a boost source for a boost controller to function. Boost controllers function by sensing a level of boost, and diverting a portion of that air pressure away from the wastegate.

So your charge piping may be at 25psi, but as far as your wastegate knows, it is being fed 15psi, where the spring starts to open. This is how your engine gets fed 25psi as opposed to 15psi which is known as 'spring pressure' or 'gate pressure'.

If you get your source from the turbo housing, or before the intercooler, you will see less boost in your manifold, because the controller is going to be using that pre-cooled, pre-pressure lost source as it's source of truth.

To avoid this, you get a source after your intercooler has done it's thing, but it HAS to be before the throttle body, which is why people almost universally use a nipple on the charge piping, before the throttle body. You do not want your boost source to be seeing vacuum inside the manifold itself, this is to avoid your boost controller trying to do much when it sees your "boost" at a negative value.

Like most things car tuning, you want the tuning to be doing as little as possible, for maximum accuracy.

[silviaz]

2 hours ago, Kinkstaah said:

The controller works by measuring your current boost from a boost source. It *has* to be connected to a source of boost.

Without this, it cannot function. You cannot boost a car without this either. It is a requirement to have a boost source for a boost controller to function. Boost controllers function by sensing a level of boost, and diverting a portion of that air pressure away from the wastegate.

So your charge piping may be at 25psi, but as far as your wastegate knows, it is being fed 15psi, where the spring starts to open. This is how your engine gets fed 25psi as opposed to 15psi which is known as 'spring pressure' or 'gate pressure'.

If you get your source from the turbo housing, or before the intercooler, you will see less boost in your manifold, because the controller is going to be using that pre-cooled, pre-pressure lost source as it's source of truth.

To avoid this, you get a source after your intercooler has done it's thing, but it HAS to be before the throttle body, which is why people almost universally use a nipple on the charge piping, before the throttle body. You do not want your boost source to be seeing vacuum inside the manifold itself, this is to avoid your boost controller trying to do much when it sees your "boost" at a negative value.

Like most things car tuning, you want the tuning to be doing as little as possible, for maximum accuracy.

Ah right thanks

Edited August 24, 2024 by silviaz