Things that will kill boost on a 20VT I5 engine

[UrS4boy]

Maybe I did not notice and someone has already written about that here. I had problems with EM to turbo sealing, it leaked and turbo did not spool correctly. Pretty difficult to check.

Not sure if I want to include that or not. Seems like there should have been some visible and/or audible signs of exhaust leakage. Solution = new 035129589D gasket (item 3 below). https://www.ecstuning.com/ES2336/





With 4 new 035145749 copper nuts
https://www.ecstuning.com/Search/Sit...5749/ES276297/

[maiks]

I was not able to see because it leaked under the turbo. In the beginning, there was not much noise. But luckily when it started to leak then it burned out pretty fast, maybe in 500km After that you can hear and maybe see also

[Quattronaut]

The N75 can also be damaged and just regulate wrong, so that is not necessarely a 1,9bar spring.

@UrS4boy: Great list, good summary, thanks for that work. Maybe here are another two canditates for you:

1: IAT Sensor G42 or its cable. Defect or corrossionat the connection possible, also wiring problems, breaks etc. Sensor is located on the "knee" of the intake manis of ADU/ABY/3B, don't know the AAN location. There is no plug; the sensor is directly connected to the wires, if the wiring is bad, it has to be solded.

2. For chipped or tuned S2 with much more boost than stock: Intake hose from airbox to turbo. Older ones can be weak- it constrings when the turbo really sucks air, getting so tight, that air flow is limitted. This is one of the hardest issues to find. It only happens, when a S2/S4 hose is used; the RS2 hose has got an ring of metal inside is, that prevents that. Hoses cannot be changed plug'n play, because connections to N75 and WG are on other sides.
I even heard of silicone hoses the did constring under extreme conditions, but those were very old ones- and I find it hard to believe.

[Dynasty]

I am in the process of trying to figure out why my C4 S6 only produces 1.8(absolute) bar of boost pressure. Any tips on where to start looking?

Old tread but... The reason I did not get more than 1.8 bar absolute was because my car is an automatic (they are limited to 1.8 bar to save the gearbox). In other word, there was nothing wrong with the car.