Alright, jspec s5 turbo motor with a bnr turbo, FMIc and a greddy type-s. 14 PSI lt10-s

Under low to mid throttle after about 10 seconds of accelerating in any gear, at any vacuum/boost between 5 HG and 10 pounds, my boost will pulse between say 8 PSI to 0 HG and back and forth really fast, for as long as I hold the acceleration. It sounds like compression surge, but pulsing. It consistently does it about 10 seconds after starting a new gear and accelerating almost any amount besides full throttle.

It did it one time at full throttle and pulsed from 14 pounds to 0 and back and forth. It was disgusting. Only that one time though.

I originally thought it was something with the bov, I tried a new bov vacuum source, and a different type-s bov we had. and nothing.. still did it.

anyone have this problem or maybe input?

 

Fuel cut? Got a Fuel Cut Defender?

 

he said LT-10s... as in microtech LT-10 ?

sounds like a boost controller problem.

 

+1

check the boost controller solenoid

 

does the car FEEL like it's fluctuating? how are you getting these numbers? are you visually looking at a gauge or datalogging?

could be a problem with the MAP sensor as well.

 

It is a Microtech lt-10s with x4 box..

It's a manual hallman? boost controller. What makes me think it's not the boost controller is that it happens between 0 Hg and 10 pounds. It's a stock actuator at 8 pounds or w/e, with the boost controller I brought it to 14.

I am watching the needle on my apexi boost gauge jump from say, I was at 5 psi when it starts happening, it will jump from 5 pounds to like 5 HG rapidly fast making a surging sound.

When I full throttle it, everything works fine. It holds boost near 14 most of the time.

and yes, the car does slow down a bit during it, not enough to notice sometimes, only at low throttles. The one time it happened under full boost, it was bucking bad..

 

I'm thinking it has something to do with restrictions.
Either my air filter, or could it have anything to do with intercooler piping/intercooler?

It didn't surge before the front mount, so could front mounting cause a turbo to surge?

There was no surge before with the top mount and the same air filter. So I'm thinking my IC is the issue. Anyone agree? Or even come across something like this?

 

remove the boost controller (the fact that it is an MBC simplifies things). Is the problem still there?

 

Well the car operated before with the same boost controller.

 

so it did it right after you installed the intercooler? you didn't leave a rag or something in your intake did you?

 

Might wanna just double check your piping connectors or pressure test the system. Thats a very odd symptom and it sounds more less like its a problem post turbo outlet and in the intake somewhere. I've heard of such a thing happening with stock 7 turbos just not on standalone systems with your boost. hmm