Boost spike really bad, should I get 34mm flapper or go external gated

[cruisintalonawd]

I had my boost set at about 14psi and yesterday it started spiking. In first it will go to 20ish, 2nd-5th 17ish. What do you think I should do, I already have ported the O2 housing, manifold and exhaust housing. Its a 14b.

 

[DJYoshaBYD]

time to go external..

 

[GSX93DSM]

If it was at 14psi after you ported things and ran fine you got other problems. I have never seen a big wastegate flapper on the 14b at that size.

 

[DJYoshaBYD]

what kind of mbc do you have?

 

[GSX93DSM]

If you are having boost creep and want to upgrade I would buy a larger turbo than spend money on the 14b with a flapper or external.

 

[gregalmighty]

what kind of mbc do you have?

Yeah, this could very well be the cause and its probably the cheapest of all the possibilities. I would start here as well. If you're not sure take a pic of it and post it, I'm sure someone can identify it. Or just go to home depot and spend a few bucks and see if that solves your problem.

 

[cruisintalonawd]

If it was at 14psi after you ported things and ran fine you got other problems. I have never seen a big wastegate flapper on the 14b at that size.

Ok I started it out at 8 or 9 then bumped it up little by little. When I got to 14 it would spike only 1 or 2 psi now its going way past my comfort level with my stock fuel

what kind of mbc do you have?

an ebay one from a friend that was working good for her at 20psi

If you are having boost creep and want to upgrade I would buy a larger turbo than spend money on the 14b with a flapper or external.

I'd rather upgrade other stuff first (fuel system) before geting a bigger turbo, you know what I mean

 

[SethA]

How much boost are you trying to run?

Your talking about creep not spike right?

If so, bypass your boost controller by hooking the boost source directly to the wg actuator. If your creep goes away your boost controller is flakey or is not installed correctly.

If it still creeps and you are trying to run around 15 psi or more porting will most likely cure the problem (it did for me). Every car is different however. I have heard of cars that creep like mad in spit of "sufficient" porting.

If it still creeps and you are trying to run lower boost a bigger flapper, an external wg, or another more drastic solution might be required.

Seth

 

[cruisintalonawd]

Spike is when it goes up and comes back down. Creep is when it just keeps building I want to run 15psi.

Forgot to ad that it goes back down to aboyut 16/17 psi

 

[cruisintalonawd]

I turbo the controller down a little bit and it hold 11psi fine

 

[DJYoshaBYD]

it really sounds like its the MBC..

"All ebay MBC's are not created equal." - Me

they can work, but they are hit and miss.. its probably a weak spring in there bouncing around.. you can try and go to home depot and put another spring in it.. I made one myself and it worked vverrryy well.. I cannot find the link right now, but if you search a bit, you will find it.. you can actually see a post where I said my mbc worked fine without a bleeder hole... you would not believe how many people were on my ass saying why I needed it, and it wouldnt hold boost right without one.. well.. mine worked great.. it actually worked like garbage with the bleeder.. I just plugged it up, though..

again, try and change the spring in the mbc to something the same exact length and width as the old spring, but stiffer..

 

[cruisintalonawd]

ok I'll try a different spring. Its now going from 12 to 18 back to 12 and then works its way back up untill I shift

 

[SethA]

I agree it sounds like a boost controller problem. I am sure you know, but I wouldn't run much boost until you get a logger and some fuel system mods.

Seth

 

[awdtsi724]

trying to run anything more than 14lbs on whats sounds like to be a stock fuel system and being untuned is nuts...it does sound like a mbc problem or you could have a leak somewhere...i wouldnt go any higher than 14lbs until u get a fuel pump and some bigger injectors along with a safc or some kinda a tuning program, or u could really get yourself into some problems..

 

[cruisintalonawd]

yeah I got a logger and I found its the MBC spring so I'm getting a new one from work tonight

 

[cruisintalonawd]

I finally got around to changing that spring and its still doing the same thing

 

[kenamond]

Have you done the basic testing? Check the MBC vaccuum lines, check that the WGA is functioning correctly (use a pressure tester or do it during a boost leak test), check that the WG flapper is not binding and that the actuator arm isn't hitting the heat shield. If all of that checks out, I'd recommend picking up a different MBC, preferably from a reputable source (not eBay).

I'm unclear about whether you changed something or not when this started happening. Did it hold 14psi fine for a while (how long)? Or did you up the boost a bit and it started happening?

 

[cruisintalonawd]

I only have a boost leak out of the throttle body shaft. The only vacuum lines I have is one to the BOV, one to the MBC, and one going to the FPR that is "T'd" to my Boost gauge. When I tested the WGA with my air compressor it started open at 9 to 11psi and was fully open at like 19 to 21 psi. But any of them that I've tested its the same way. I know the arm isn't hitting anything because there isn't anything for it to hit and the flapper move freely.

It was holding 14 psi strong for a couple day untill I did a boost leak test then I had to rush to get everything put back together and forgot to plug the MBC back in then I took off hit fuel cut and looked at my gauge and it was at 25 psi so i left off on the gas and realized what I forgot to do......Do you think it would be ok to fined a really good used one for sale I don't have much money at all

 

[cruisintalonawd]

how about these?????

eBay Motors: HALLMAN ES MANUAL BOOST CONTROLLER KIT BRAND NEW TURBO (item 350056398466 end time May-10-08 15:27:23 PDT)


eBay Motors: Hallman Manual Boost Controller Adjustable (item 300222789205 end time May-12-08 20:30:00 PDT)

 

[silver bullit]

1st one is junk

The 2nd one i have in red, works great i say get the 2nd one.

Ebay mbc are junk you cant cheap out on parts than can cost you your motor.

You just need to port the wastegate or get a better o2 housing

 

[cruisintalonawd]

Ok thanks I would like one of those Hallmans that you can control from inside the car, but I definitely don't have that much cash

 

[SethA]

1st one is junk

The 2nd one i have in red, works great i say get the 2nd one.

Ebay mbc are junk you cant cheap out on parts than can cost you your motor.

You just need to port the wastegate or get a better o2 housing

Hey silver, I don't know if you saw post #10 but he says he can run 11 psi just not 14 psi. That would indicate that bypass flow isn't the culprit. I agree that running a good boost controller is key. I have no idea why it was working and then the overboost caused it to be ok at 11 but not 14?

Seth

 

[Mr Peepers]

http://www.dsmtuners.com/forums/bol...-fluid-dynamics-thermal-insulation-etc-2.html
post #'s 51, 54, 57, and 58, specifically.

And http://www.dsmtuners.com/forums/newbie-forum/262063-boost-spike-fade-leak.html

The gist of it, enlarging the bleeder hole one drill bit size larger may help with spike.

 

[silver bullit]

Hey silver, I don't know if you saw post #10 but he says he can run 11 psi just not 14 psi. That would indicate that bypass flow isn't the culprit. I agree that running a good boost controller is key. I have no idea why it was working and then the overboost caused it to be ok at 11 but not 14?

Seth

Dont question my authority. Sike

He still needs to get a better mbc, then needs to make sure it is hooked up correctly not tee'd into the bov etc.

 

[cruisintalonawd]

I don't have it T'd into any lines its coming off the jpipe. I found the hallman in car controller I wanted for a really good price, I will let you know how that goes. I also hooked up the stock BC and it holds at 10 but the needle shakes like crazy.