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Discussion Starter #1
Well lads I’ve a turbo is200 running a SW turbo kit set up td04 external wastegate.
Was running 100% till yesterday when she start bogging down sometimes not all the time could be 1/2 times a day but it’s worrying me as it would. Let’s say I start the car leave her heat for while and then go to drive and boost shE would bog and sound horrible giving her the beans anyone ever have this problem
 

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Discussion Starter #3
Any check engine light codes?

Boost levels drop when it bogs down?
Tbh she’s never actually held 7psi boost since I’ve fitted the kit I’ve checked for boost leaks have none, so I brought it to SW and he said she feels 100% just boost gauge isn’t reading right, so tbh I donno how to answer that question cause I don no myself😕
 

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Discussion Starter #6
Does it produce any boost at all on your gauge? The gauge I assume isn’t from the SW company right? It’s an after gauge you installed?
It does produce boost in gauge like it goes to 6 then drops off but doesn’t feel like it’s dropping off and yeah was from SW company
 

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2002 Lexus IS300
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Sorry I am not familiar with SW turbo kits but they all are supposed to do the same thing lol. Does their site say the kit is supposed to make more than 6psi?

Also you say the gauge falls but the power still feels ok? The TD04 is a very small turbo. It is not designed to maintain anything over 8psi really. They are mostly internally gated to 7-8psi max. Even when turned up to 9-10psi they are extremely inefficient and just blow hot air into the engine. Peak boost in your car I imagine is around 4000-4500 rpm and then it tapers off up to redline to maybe 4-5 psi?

For reference the TD04 turbo is what is on the very early WRX (2002-2007ish) If you have ever driven one of those in stock form, you will notice that they spoil quick and then fall flat on their face above 5k rpms. The boost tapers off severely.
 

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Sorry I am not familiar with SW turbo kits but they all are supposed to do the same thing lol. Does their site say the kit is supposed to make more than 6psi?

Also you say the gauge falls but the power still feels ok? The TD04 is a very small turbo. It is not designed to maintain anything over 8psi really. They are mostly internally gated to 7-8psi max. Even when turned up to 9-10psi they are extremely inefficient and just blow hot air into the engine. Peak boost in your car I imagine is around 4000-4500 rpm and then it tapers off up to redline to maybe 4-5 psi?

For reference the TD04 turbo is what is on the very early WRX (2002-2007ish) If you have ever driven one of those in stock form, you will notice that they spoil quick and then fall flat on their face above 5k rpms. The boost tapers off severely.
The kit is meant to make 7 psi I don’t really care about the psi it’s just she honestly bogs the boosts out of nowhere lately
 

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Goes down to 4 and sometimes 2
If this has been the case since you installed the kit then this further solidifies why the TD04 isn’t the correct turbo for that engine. Forgive me as in the states we don’t have the first Gen is200. Your car does have the 1G straight 6 right? That engine is simply “too big” for that little turbo. The turbo is actually becoming a restriction the higher you rev it because the engine is simply starting to outflow what the turbo is capable of making. Thus the boost is tapering off because it simply cannot keep up with the airflow demand of your engine.
 

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The TD04 is fine and well suited with the 6 cyl 2litre, they don't handle boost very well in stock form, weaker bottom end than a 2jz. The 4 cyl 2 litre ones are better.
 

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The 1g uses map so no maf to worry about unless you have had to add one with the kit. What ECU is it running, and what is the A/F ratio doing when under boost and when its bogging?

Could be electrical like spark plugs or coils, maybe injectors or fuel pump. Hard to know without more info and diagnosis.
 
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