Any ideas why my boost falls down from 14 psi in peak (3700 rpm) to 10 psi from 4100 to 5000 rpm and even to 8 psi from 4500 to 4900 rpm and then goes up to 11 psi from 5000 to 5200 rpm and then goes once more down??

That was a 4th or 5th gear pull,

Boost leak/to small turbo/to restrictive exhaust? Spark table needs dyno?
Any ideas where to start from?

It hasn’t been dyno’ed yet, I don’t want to spend money with this boost, the minimum boost level I want to achieve is constant 14 psi

 

what is controlling boost?

 

I would start at your wastegate and boost controller

 

its GM EBC from DIYAutotune, but I've just received their latest EBC selenoid, I'll check in few days time if it resolves my problem.

If not I'll check the wastegate.

 

so you're running open loop boost control then right?

you need to un-comment out two lines of code so you can log the BDuty% (boost duty cycle %) and you can then probably blame how your DC% table setup currently.

fwiw, when the temps get warmer out, you'll make less boost if running open loop. and unfortunatly the closed loop code for MS-I is not well developed.

 

get an mbc.
profit

 

are you truly loosing boost?

because if you are, you should just stop.

 

I had this weird dream where I lost my boost, and I was running all over town trying to find it, and I was faster on foot than I was in a car because I had no boost. Then this weird storm happened and I had to go home, and my boost was sitting right on the counter. It was crazy.

 

Don't let your boost loose.

 

dont make me loose my phallus

 

Dump the EBC. They are absolutely worthless when used with an MS1 board. I had far better luck using an MBC sourced from the coldside.

 

I've fixed it. The EBC got too hot and didn't work as it should. I've mount it in the coolest place under hood (near hole in firewall made as cold air intake)and it's perfect now.

 

it reacts to ambient temps; since it's less dense when it's warm, less boost.