Infinite Boost - MBC not working

[swnkylaxplyr]

I have a 2G GSX that had an EvoIII 16G, 3" catback, hard UICP and Greddy RS when I bought it. Ever since I've had it, it has wanted to boost to 20psi+ at which point I hit fuel cut. I just bought a Perrin MBC and installed it yesterday. Neither my compressor housing or j-pipe have any nipples on them, so I used the LICP fitting that the BCS was formerly hooked up to as my boost source, and of course I connected the other end to the wastegate actuator. After noticing no difference at the lowest setting, I tried reversing the MBC just to check - worse. Then I took the MBC out and hooked the wastegate actuator directly to the LICP and it was the same as before. What can my problem be?

 

[95blackGsTurbo]

Do a boost leak test to make sure you are even making 20psi or it is just leaking it out.

 

[swnkylaxplyr]

Do a boost leak test to make sure you are even making 20psi or it is just leaking it out.

I haven't been able to do a boost leak test, but I smoke tested it in the past and found no leaks. Obviously, this doesn't mean there aren't any leaks under boost, but just thought I'd mention it.

Also on a hunch, I checked the wastegate actuator arm and I couldn't get any movement out of it manually. Is this my problem?

 

[standard235]

Boost creep?

 

[swnkylaxplyr]

Bump

Any suggestions about the frozen wastegate actuator? Would that be my problem?

 

[rlacasse1]

Yes that can cause the problem. If the wastegate is stuck closed bacause of a frozen actuator then you will boost like crazy.

 

[dangler]

Yes, that would most likely be your problem. If your wastegate isn't able to open up to dump the excess exhaust flow then you are going to continue to build boost. Disconnect your actuator from the wastegate flap. Check if the actuator can be pulled out and springs back, or you could check it with air. Then check if your wastegate flap is not frozen in place, it should just fall open and shut with no resistance. Whichever one doesn't do the job is the guilty party, or they could both be bad, but not likely.

 

[swnkylaxplyr]

Yes that can cause the problem. If the wastegate is stuck closed bacause of a frozen actuator then you will boost like crazy.

Awesome thanks for the replies.

 

[rlacasse1]

No problem.

 

[asg1089]

i have a similar problem. but i have done a blt, i have checked the wastegate, i have replaced ball and spring in mbc. nothing seems to work. honestly man it is just the evo3 and creep. it is nearly impossible to control boost on these things without porting and/or going to external wastegate. i have tried everything to control the boost b/c i was on a budget and couldn't get the tuning or fuel system. lucky enough everything is in the mail now. i mean don't take this as it is impossible to control, it is just extremely difficult. i got it to hold 18lbs for a week and it has never done that since. but keep trying you might find somthing i didn't. good luck.

 

[swnkylaxplyr]

Ha thanks for the confidence boost Seeing as how my wastegate actuator does seem to be frozen, I'm hoping that's my problem, but if not I guess I've been warned .

 

[asg1089]

hahaha sorry man, didn't mean to drown your hopes. i mean my setup might just have not liked me or somthin b/c i know people who can control it. it's just a pain. fix the actuator and keep trying. as i said, i was at one point able to control it but for some reason can't anymore. it's really weird.

 

[swnkylaxplyr]

Well I took the actuator off and after testing it, it would retract when pulled, albeit roughly. I cleaned it up a bit and worked some blaster into the spring until it worked smoothly. I also checked the wastegate flap, which moved freely. I sprayed that with pb blaster too for good measure, and then put it back in the car. Unfortunately, when I took it for a test drive the only difference I noticed was that the turbo response seemed quicker - it still boosts to 18 psi (and beyond, I just didn't want to take it any farther).

Am I just having some good ol' evoIII overboost, or is there something else? Shouldn't routing a vacuum hose from wastegate actuator to boost source at least handicap my boost to 8 psi or something if all was working correctly?

 

[rlacasse1]

Yes. It would. Do you still have the boost controller on it. I had issues non stop with a MBC. I eventually took it off and now have nothing on it.

 

[swnkylaxplyr]

Okay. I put the mbc back in after messing with the actuator, but I'll try without the mbc and see what happens.

 

[steele_verus]

Since you already took it off, this may not help, but one way I check my actuator and valve is to hook a vacuum line to your actuator, and then get an air hose with a fitting that allows for adjustable air pressure. I then start with a little bit of air and build up until the arm retracts. I had an evoIII 16g with a bad diaphram on the actuator. I thought I was just getting boost creep, but after I replaced the acuator, it boosted at 22psi no problem.

 

[swnkylaxplyr]

I took out the MBC and run a hose direct from actuator to boost - still no change.

 

[joegamma1]

Remove the wga arm and let it flop so the wg can open freely, if you have creep it will build boost if not you dont

 

[swnkylaxplyr]

Changed out the actuator - same problem. If it helps, my vacuum at idle is 15in, so its a little low. I guess I'll start looking for vacuum leaks?