16g boost issues

[ypnas777]

I recently installed a ported small 16g into my 2g DSM. After installing it and taking the car out for a spin I noticed that under wot, the boost goes up to about 14-15 psi and holds it until redline then when the car shifts to 2nd(it's an automatic) the boost goes down to about 10-11 psi and holds this until redline for the rest of the gears. I recently bought a hallman mbc thinking it was my old mbc but that didn't make a difference. Another thing is that the mbc is set all the way out..... Any ideas?

 

[andymoraitis]

Usually that happens the other way around since the lower gears have less load and the upper gears have a tendency to create more boost. You're not listing any injectors or a pump in your mods, so I would cautiously increase the boost to see if it changes anything in 2nd gear and above. It may be backed out so much that it won't hold steadily for you.

It would also be a great idea to run a boost leak test as you could be bleeding boost under greater load in 2nd and 3rd.

Let us know what you find,

Andy

 

[ypnas777]

I have a 1g bov and last time I checked it was holding 18 psi. I also know that my injector seals are leaking. Could this cause that boost issue?

 

[andymoraitis]

I have a 1g bov and last time I checked it was holding 18 psi. I also know that my injector seals are leaking. Could this cause that boost issue?

I caught that and edited my post while you were probably reading it. To answer your question, yes, leaking injector seals can create enough of a problem to bleed that much boost. It's just like any other boost leak. When replacing them, pick up a set of Viton seals from:

http://www.fuelinjectorclinic.com/cart/seals.htm

I swear by these and they hold big boost. When replacing the o-rings and seating them into the fuel rail, make sure that you lube them with a bit of motor oil so that they don't tear as you're installing them. Also using a twisting motion helps them seat more easily.

 

[ypnas777]

So a boost leak would cause these symptoms? I just want to make sure that the turbo isn't bad or anything. I was just wondering because it is able to hold around 13-15 psi to redline in first gear.

 

[andymoraitis]

Sure it will. If you have a closed system with no leaks, boost will hold steady. If you're leaking boost, it simply can't. The reason you're seeing it more in 2nd and 3rd gear is because the more load there is on the motor, the more, for lack of a better work, pressure is exerted on the system. Also, 1st gear doesn't last long while 2nd and 3rd do so you're more likely to pinpoint issues in those gears than in 1st when it comes to boost leaks.

I'd also play with the MBC as mentioned before, but be careful since you're on the stock fuel system.

 

[ypnas777]

Does anybody know what the stock 16g actuator is set at? the 13-15 psi in first gear seems a bit high considering my mbc is set all the way out but I dont know....shouldnt the boost only go as high as the stock actuator setting if I have my mbc all the way out? Sorry for all the questions but I just want this to out... Thanks

 

[JayRolla]

Mine was at 9psi on my evo 16g. Take the MBC completly off to get back to stock boost, even all the way out it still can push more than the actuator.

 

[s13totsi]

I am having a very similar problem, i have 16g and 550 injectors. iv tried every way to use the hoses from the bov setup and i cant seem to create more then 11 lbs. my injector seals are new and the intercooler, from what i could see is working well. brand new evo3 16g from turbochargers.com. could it be lubrication issues inside the turbo that would make it create less boost??