Weird boost problem! Please Please Please help! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jdm_s14_zenki · 03-23-2006, 01:04 AM

I have an S14 blacktop in an S14..Stock turbo, stock intercooler & piping. Walbro FP, Manual Boost controller, AFC...

The problem started when i replaced my boost hoses that go from the intercooler piping to my MBC and to my wastegate actuator.

I cannot boost more then .5 bar!! Ive looked like crazy for leaks, replaced hoses and hoseclamps, checked timing, cleaned out intake system with cleaner.. and i still cant find the problem!

My car idles nice @ 850rpm & builds boost just fine then stops building at .5 bar.

Ive checked my turbo to see if it would boost... i disconnected the hose that goes to the actuator and and drove it. boosts very high and just fine when i do that but if i dont left off the gas, it'll boost way too high...

Then i connect the actuator hose again and it wont boost more then .5 bar.

Ive also taken off the MBC completely by running the hose from the intercooler piping directly to the actuator and still only .5 bar (maybe .6 at most)

I bought the MBC from HKS about a year ago and its been set @ 14psi since with no problems.

ANY SUGGESTIONS??? ANYTHING THAT IM MISSING??? Ive had this problem for 3 weeks now and im tired of messing with it..

BTW: My car doesnt buck under load, like i said, idles just fine, and builds boost just fine...just wont go any higher then .5 bar

jdm_s14_zenki · 03-23-2006, 03:52 AM

bump...i dont wanna spend anymore needless $$ trying to figure this thing out :[ im broke

just a thought...would that little "flow restrictor" thing have anything to do with it? its that little thing that you put inside the hose that goes to the MBC...if so...when i replaced the hose..i didnt put it in my new hoses..

jdm_s14_zenki · 03-24-2006, 01:22 AM

nevermind guys...it was the MBC, i replaced it and now it works...thanks for not helping me!

smithers584 · 03-24-2006, 03:27 PM

thats the best way to learn man!

03-23-2006, 01:04 AM	#1
jdm_s14_zenki Zilvia Addict Join Date: Jan 2006 Location: Orange County Posts: 703 Trader Rating: (1) Feedback Score: 1 reviews	Weird boost problem! Please Please Please help! I have an S14 blacktop in an S14..Stock turbo, stock intercooler & piping. Walbro FP, Manual Boost controller, AFC... The problem started when i replaced my boost hoses that go from the intercooler piping to my MBC and to my wastegate actuator. I cannot boost more then .5 bar!! Ive looked like crazy for leaks, replaced hoses and hoseclamps, checked timing, cleaned out intake system with cleaner.. and i still cant find the problem! My car idles nice @ 850rpm & builds boost just fine then stops building at .5 bar. Ive checked my turbo to see if it would boost... i disconnected the hose that goes to the actuator and and drove it. boosts very high and just fine when i do that but if i dont left off the gas, it'll boost way too high... Then i connect the actuator hose again and it wont boost more then .5 bar. Ive also taken off the MBC completely by running the hose from the intercooler piping directly to the actuator and still only .5 bar (maybe .6 at most) I bought the MBC from HKS about a year ago and its been set @ 14psi since with no problems. ANY SUGGESTIONS??? ANYTHING THAT IM MISSING??? Ive had this problem for 3 weeks now and im tired of messing with it.. BTW: My car doesnt buck under load, like i said, idles just fine, and builds boost just fine...just wont go any higher then .5 bar

03-23-2006, 03:52 AM	#2
jdm_s14_zenki Zilvia Addict Join Date: Jan 2006 Location: Orange County Posts: 703 Trader Rating: (1) Feedback Score: 1 reviews	bump...i dont wanna spend anymore needless $$ trying to figure this thing out :[ im broke just a thought...would that little "flow restrictor" thing have anything to do with it? its that little thing that you put inside the hose that goes to the MBC...if so...when i replaced the hose..i didnt put it in my new hoses..

03-24-2006, 01:22 AM	#3
jdm_s14_zenki Zilvia Addict Join Date: Jan 2006 Location: Orange County Posts: 703 Trader Rating: (1) Feedback Score: 1 reviews	nevermind guys...it was the MBC, i replaced it and now it works...thanks for not helping me!

03-24-2006, 03:27 PM	#4
smithers584 Zilvia Junkie Join Date: Dec 2004 Location: sc Posts: 416 Trader Rating: (0) Feedback Score: 0 reviews	thats the best way to learn man!