ktnguyen

Question about Vast's TCD. Correct me if I am wrong. The TCD changes the voltage that the MAP sees. This makes the ECU believe it is running less boost so that it does not cut throttle. For example without TCD you run 25 psi the ECU wants 20 and cuts throttle for safety. With TCD you run 25 psi and the ECU sees 15 psi and is fat, dumb and happy.

My question is if the ECU only believes the turbos is pushing 15 psi how can it safely deliver the fuel for the actual 25 psi of boost?

Secondly, PV=nRT. does it matter what size hoses you run to and from pressure/vac lines? For example if you are trying to read boost from a gauge does the reading change depending on the diameter of your hose? I am guessing not, but how come?

What about length. If I run a 20 ft hose to a mbc will it take longer for pressure to fill that line? Will there be overshoot or lag?

sj6sp

Fueling is based on MAF readings not MAP (unless your MAF is dead and car reverts to speed density).

Use Vacuum hose so it doesn't collapse when not in boost. Small is not a problem.

At some point, length will affect response time. Who knows how long but these turbos spool quick when they come on. Keep MBC hose to a few feet and you're fine. Also, the more "tortuous" the path of the hose, the more chance of a kink in the line (very bad).

Boost gauge hose can be longer since response lag wont affect anything other than your gauge.

ktnguyen

Thanks. What happens to boost when using TCD/MBC only and I flash to stock (GIAC)?

sj6sp

Stock programming is in the 8-10 range. When the MAP sees higher than the requested 8-10 the ecu is gonna get pissed.

Besides, if you are on K03s you shouldn't run MBC only unless you don't care about blowing them.

ktnguyen

AWE Stage 3. What do you mean locks boost to 14.5 psi and lower?

nyet

It prevents the ECU from ever seeing any boost higher than 14.5psi

sj6sp

There is a TCD that limits MAP sensor readings to <14.5 psi for use with K03 software and then there is a TCD to limit MAP sensor readings to <18 or 19psi often used with AWE stage 3 to increase boost.

What software/fueling/turbos do you have and what are you trying to do?

ktnguyen

I have AWE stage 3 full kit. I run test pipes. Pair that with the hot season and little back pressure and I get boost deviation so the N75 can not control boost and my boost goes back and forth between 25 and 15 psi.

I am planning on going vast MBC and TCD for the AWE file.