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Discussion Starter · #1 · (Edited)
So I just bought a used 04 STi and I need help with its current issues. First off it overheats when I’m in idle for a while but cools down when I drive. Coolant is topped off and the reservoir is at F. I suspect it’s the fans or a maybe a relay ? Second thing, it smells like gas after driving, is it an exhaust leak ? I’ve never seen any fuel leakage. And third .. I don’t know wtf I found under the carpet of the passenger foot rest area, but its a amp looking thing that says turboxs on it. Current after market parts that I KNOW OF right now is a Cobb cold air intake and a HKS BOV. Please help me
 

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You could have a fan issue or even a water pump issue. Some highly modified vehicles will also tend to overheat at idle. If it has a front mount it could also be restricting air flow to the radiator depending on how it's installed. See if the fans are on at idle.

As for the box, I'm not familiar with turboxs and their product line up but that sounds like some sort of stand alone ECU. I would suspect that if my assumption is true then chances are the vehicle is modified beyond what the stock ECU is capable of handling.

Either way without the ability to tune the car I would completely avoid an intake change. I would also entirely avoid a blow off valve as any vehicle that uses mass air flow over speed density won't opperate properly with a blowoff valve. This is why they offer bypass valves from the factory. The air is already metered and venting it to atmosphere causes fueling issues with throttle input changes.
 

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Discussion Starter · #3 ·
You could have a fan issue or even a water pump issue. Some highly modified vehicles will also tend to overheat at idle. If it has a front mount it could also be restricting air flow to the radiator depending on how it's installed. See if the fans are on at idle.

As for the box, I'm not familiar with turboxs and their product line up but that sounds like some sort of stand alone ECU. I would suspect that if my assumption is true then chances are the vehicle is modified beyond what the stock ECU is capable of handling.

Either way without the ability to tune the car I would completely avoid an intake change. I would also entirely avoid a blow off valve as any vehicle that uses mass air flow over speed density won't opperate properly with a blowoff valve. This is why they offer bypass valves from the factory. The air is already metered and venting it to atmosphere causes fueling issues with throttle input changes.
Its a top mount so I don’t think restriction is a play in the overheating issue. I bought fans already but yet to install. I’m gonna be safe and replace the water pump as you mentioned, maybe even the radiator and the pipes/hosings. Is it wise to also get a new belt and tensioners/pulleys for the water pump swap out ? Or can that wait. Also I don’t really understand the bov issue with fueling. Please elaborate more so I can understand. Your knowledge is greatly appreciated XJman
 

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Yeah, it's a great idea to do the belt, pulleys and water pump at the same time.

Mass air flow works by gauging the amount of air in the intake by a sensor mounted by the filter. It is calibrated to the intake shape, size, and turbulence on the particular intake. Once the air passes that it is compressed by the turbo and passed through a heat exchanger into the intake where the ECU uses the maf sensor reading and temperature to inject the proper amount of fuel. When you step off the throttle the air not yet in the intake vents back into the system when the throttle plate snaps shut. That air is already accounted for in the previous process.

With a vta blowoff valve that air is lost and the ECU continues to send fuel like it's all still there. Causing the engine to run rich for a period of time. This can cause plugs to foul and carbon buildup. In the short term it's better than lean, in the mid to long term it has the same result ending in knock and eventual engine damage.
 

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Suspect air pocket in the cooling system.

Suspect leaking fuel lines above the intake manifold where the hard lines meet rubber. A known issue.

The TurboXS piggyback may have archaeological value; contact the Smithsonian or something.
 

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Discussion Starter · #6 ·
Yeah, it's a great idea to do the belt, pulleys and water pump at the same time.

Mass air flow works by gauging the amount of air in the intake by a sensor mounted by the filter. It is calibrated to the intake shape, size, and turbulence on the particular intake. Once the air passes that it is compressed by the turbo and passed through a heat exchanger into the intake where the ECU uses the maf sensor reading and temperature to inject the proper amount of fuel. When you step off the throttle the air not yet in the intake vents back into the system when the throttle plate snaps shut. That air is already accounted for in the previous process.

With a vta blowoff valve that air is lost and the ECU continues to send fuel like it's all still there. Causing the engine to run rich for a period of time. This can cause plugs to foul and carbon buildup. In the short term it's better than lean, in the mid to long term it has the same result ending in knock and eventual engine damage.
Understood.. I’ll work on getting a AP as soon as possible to solve that issue. If you have any other tips on the car please let me know. I enjoy this car a lot, it’s always been a dream of mine to own one. I want to make it last as long as possible till I have to build a longblock for it.
 

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Discussion Starter · #7 ·
Suspect air pocket in the cooling system.

Suspect leaking fuel lines above the intake manifold where the hard lines meet rubber. A known issue.

The TurboXS piggyback may have archaeological value; contact the Smithsonian or something.
Would I have to bleed or drain it completely.. not really familiar with air pockets in the radiator.

As for the fuel lines I will double check on that. Would there be any other reasons for the smell ?

Archaeological value ?? Lol if they’re paying I’m selling.. I’ll be running an AP anyways.

Thanks for the info. If you have any other tips or knowledge you’d like to share I’d appreciate it. This dream car of mine will be built for a daily. Just trying to enjoy it for now until I have to build a longblock for it.
 

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Search the forum for “burping” the cooling system.

A PO172 would reflect a rich condition — another gas smell explanation.
 
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