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How To: Manual Boost Controller


bond1318

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I have a question on this topic, has anyone had any problems with their car in that with a MBC fitted the ecu senses the higher boost and compenstates for the higher boost by reducing it immediately back to the chipped boost level?

I was running 1.3 bar for ages but this has suddenly started happening since I got a chip to sort the fuelling Sad

I have tried loads to sort this but can't figure it out

I am sort of thinking that I was better off with the standard chip now

Confused

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sounds weird. but im not chipped yet and i use an mbc.. not quite running at 1.3 bar, i mean thats like 19 psi. without a chip you must have been sucking gas down at 10 mpg.

anyways, on a stock system the ecu doesnt re-correct the boost, it just compensates. if youve got an MBC, the boost goes to what the mbc is set to. all the ecu does is compensate by putting a little more gas into the air/fuel mix because it does notice the overboost condition (thus lighting the check engine light). once you chip the engine it is supposed to correct the air/fuel ratio by incorporating the increased boost into the presets, so i cant see why chipping your car reduced your boost level. Confused

*also* does anyone know how to remove the stock solenoid properly? i know that one hose goes to the wastegate diaphragm, one goes to the intake line, and the third hose goes to a location near the turbo. if i disconnected the solenoid and replaced it with my MBC, which line do i *not* need to reconnect? someone had posted that you could leave one line left on the solenoid, but between the intake line and the one going near the turbo, im not sure which line it is that you are supposed to leave out. any help??

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The ecu compensates for the higher boost by opening the turbo control solenoid and letting the excess vacuum/pressure bleed off into the fresh air intake hose ( down the blue pipe).

the theory of the MBC is that the air is bleeding off before the sensor and the ecu can't see the higher boost at the turbo only from the manifold pressure sensor and from the amount of air going through the MAF sensor. Therefore it wont open the valve and let the excess pressure out.

Also I'm not sure which 2 hoses to hook up to remove the original controller can anybody help ?

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yes yes.. ive been down that road. i did a whole R&D thing with myself to try and find out a way to make a boost control valve because i couldnt justify paying 50 dollars for brass fittings, a spring and a ball bearing. i went to three different stores in my town trying to find the right combination of brass fittings with the right size hose barbs and what not, and then i had to find the right tension spring and so on and so forth. by the time i finally had the right combination, i was so frustrated that i felt like it would have been worth the 50 bucks just buying it from the beginning. anyways, after i made it, i found it didnt work as well as i had wanted it to. the adjustments kept coming loose, the spring would wear out, and i finally just bought one cuz i was sick of it not working right. i wanted to make one like the one they sell, but i couldnt find those brass pieces anywhere. the company i bought it from machines them. but yea, you *could* make it yourself, but i dont recommend it.. Rolling Eyes

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well the 12t isnt menat to go that high. of course there are ways you can make it boost that much (cough cough carlos Very Happy) but what i read here and there says the efficiency of the 12t runs out at like 16 or 17. after that the boost it produces becomes too hot to be as effective as it could be.

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