Nissan 200SX Club - South Africa

Hi guys, ive got a bit of a problem, its been there before i did the FMIC and its still present, i installed my manual boost tap from MR TURBO a while ago, its connected to my external wastegate currently as folows:





after a bit of driving around and tweaking i got it to where i wanted it, at approximately 0.9bar. happy with that setting i made a cut mark on the tap and the controller to be able to see my benchmark for further tweaking in future.

Then the next day i got in my car to take it to work, drove it a few blocks to get warm and i started boosting it, and dam did it feel good, i checked my gauge and i saw in 3rd gear i was now getting 1.2/1.3 bar boost, i thought woah thats not normal, i pulled over got out and checked everything and nothing came off and all was how it should be, so i got back in and drove some more and after a few half boosts (scared to boost full rev up to 1.3bar) and after a while the boost level then settled again at 0.9 bar and didnt peak or go over and all was as it should be again without touching anything, it seems it does this everytime i drive the car after its stood a while, i did some reading and saw some people say its due to the wastegate temperature, the spring is maybe not hot enough yet and it changes the way the boost reacts, but i never ever had such issues with the wastegate when i was running it straight vacuum from compressor, it would never go over 0.7 bar no matter how hot or cold it was, it would be stable, only since installing the controller im having this boost problem.

i also had the controller set up like this for a bit:



and i managed to get it also to around 0.9 maybe a bit over but i couldnt really test it fully as a vacuum hose tore and it overboosted and i thought it was the layout so i reverted back to the first setup thinking it was safer and less complex so less to go wrong, plus i read you only want to use top boost nipple on wastegate if you want to raise boost high above 1bar.

at the moment i have a standard Excell 38mm wastegate with a 0.6bar spring fitted.

What do you guys think is the problem and how could i fix it, if i turn the boost controller down then when its cold it boosts 0.9-1bar but then after boosting a while it drops to like 0.7 which is lower than i want it, i dont know what to try.... would connecting to the top port give me a more stable boost? or could it be a faulty boost controller, i got it brand new from mr turbo and its the first time im using it.

well i wasnt tired so i decided to test the setup with the use of the top wastegate port as above,



i started off with the controller just slightly open only letting slight pressure to top port to help keep wastegate open later, i drove it and it just wanted to boost to the moon, the screamer didnt even scream so my wastegate was not opening atall. So i pulled over and turned the boost controller all the way to the lowest setting only letting the tiniest amount of pressure reach the top port, drove it again and the wastegate is opening and the screamer is going, but its boosting 1.2 bar in 3rd WOT it does seem more stable the setting but its too high, and the tap is at its lowest setting now so wont be able to bring boost down lower than that 1.2 in this configuration, so flip i dont know whats the way to go then. But i also saw on other threads that some systems have a vent on the top hose, because thinking about it if the boost controller is closed even though its letting very little pressure onto the top of the diaphram it is creating resistance which is being built up in the chamber as the air has no where to vent and the bottom does not have enough pressure to push up and open enough, here they show a system with a vent:

My first thought here is boost controller. Mr Turbo crap ?

I would use carburetor jets as in your "port" configuration and leave the "controller " out of the equation totally.
In effect you are simply "bleeding" control pressure off the bottom port.

If you must use a controller , I normally get them from Hydraulic or pneumatic suppliers instead.
Also remember that line or hose diameter is also important but to a lessor degree.
Lines should also be as short as possible.

Where are you taking the "control" pressure from ? Comp housing or manifold ?
I would take it from the manifold, excludes losses in between..

I'm getting pressure from directly compressor housing like most factory setups, i read manifold pressure can be tricky due to there being vacuum aswell, would have to make use of a check valve, yea so far I'm not atall happy with this crap boost controller but when i got it i was hoping it would be simple and reliable, guess not, please BG give me an example of the method you would use to control boost effectively, i cant afford an electronic controller though

I've got a stupid mr turbo bleed valve and have had no issues with it i can get my boost to 0.8 no issues have you tried just running no bleed valve? how does it react to that? do you get stable boost at 0.6 or so?

Hey, yes direct vacuum hose from compressor to bottom port of wastegate and top port vented it boosts stable spring pressure 0.6/0.7 no problems, i tried connecting the bleeder both ways above, the first way i can get it to 0.8 but only after boosting a while its stable at 0.8, otherwise early it spikes a shit lot

maybe it is the bleed valve mr turbo doesnt sell the best quality stuff maybe find someone with a working bleed valve and test it on your car

What sort of electronic boost controllers can i look at that would be reliable and not cost a million dollars such as the greddy ones haha

I have an AEM Tru boost one which is waaaaaaaay less expensive than the fancy Turbosmart ones available. It's simple, reliable and does what it's supposed to do without any issues. Got mine from Importparts as always, give Jerry a call if there's no place in CT that sells them.

Truth be told, I'd love one of those top of the line Boost Controllers that can only be setup by NASA engineers, but it's a bit overkill for my stock setup.

http://www.aemelectronics.com/?q=produc ... controller

Greddy PRofec B-Spec II

Buy right, buy once.

Enzio wrote:Buy right, buy once.

Agreed...

Haha but dam R3000+ for a boost controller, that's more than my turbo and manifold combined

always found manual boost controllers eratic.. good advice up top , buy right, buy once..

I dont suppose anyone has a used one for sale? anything quality, ive disconnected that other crap and im running plain wastegate pressure now, car feels so slow now, but boost is stable and atleast i wont kill my engine, rather be safe until i can sort something reliable out

well great news! my problem is fixed, after alot of research and discussions with a few tuners the next item for inspection was the wastegate (excell 38mm) which i bought second hand in very good physical appearance and was told that it was used for a week and never opened, well i took his word for it at the time and never suspected it to be a problem until my one wastegate stud snapped off and i thought while it was off let me send it in to excell for a service, heres what they found:

home made grinded spring fitted which was completely wrong size in diameter aswell making the piston move skew:



and here you see that the wastegate seals were greased which apparently causes the seals and piston not to work correctly as according to excell they are special seals which are made to operate dry.


so after R550 for new spring, serice, machining, seals etc etc, i put the wastegate back on and shes holding boost steady hot and cold no more eratic boost creep or boost drop, so happy