The hallman MBC I've been using for the past 2 years all of a sudden is starting to act funny. Boost is now inconsistant during spool up. If I smash the gas @ 3k, boost starts to build and then all of a sudden stop as if the WG opened up. it will usually sit at the same psi for a little bit and then suddenly boost shoots back up to where it should be.

Below is an example of what i'm trying to explain.






You can see the boost flatten out and then pick back up where it left off again after a few hundered RPM.

I took it apart, cleaned evrything and reinstalled, same result. I even switched to another one, now I'm using the Joe P. MBC but its still doing it.

anyone experienced this before?

 

up

 

Sounds like a weird leak. Do a leak test.

 

i would say it may be dirty... take it apart, clean it and lube the ball and spring with some lithium grease and see if the problem is still there.... also as stated above, leak test

 

leak test was performed and its all good. I tried taking apart the hallman and cleaning/greasing but it had no effect. I even tried switching to another known working MBC (Joe P.) but for some odd reason the problem is still there.

 

maybe your wastegate is fudged

 

It's hard for us to say without being near the car, man. You might want to take it to a shop to see.

 

there has to be a leak. small one. either in the vacuume lines or the intercooler lines. also, check the maf sensor. plugged in? corrosion? what about the oem boost control valve, still capped?hope this helps.

 

I'll do another boost leak test, but I'm sure thats not it since I test it on a regular basis. MAF is plugged in, I don't know how that would effect boost though. Also my stock boost solenoid is pluged in electronically, the two ports are open but that doesn't matter.

I'm leaning towards something being up with the Wastegate, since it did the same thing with BOTH boost controllers I tried. I'm going try another spring and see what happens

 

i wouldnt say its the spring at all, if several boost controllers give you the same result. you may have a leak somewhere... but if you tested and it was ok, then i would agree with you and say the waste gate. Order the forge one, its a direct replacement and will hold boost better anyway...its not too pricey either

 

Both the hallman and Joe P. ones were working perfectly before, I don't see a need to order a new MBC. Although I have heard good things about the forge units.

 

no, i didnt mean the mbc, i meant the forge wastegate

 

ohh, my bad. I'm actually running an extrenal tial 38mm WG.

 

well then...im at a loss lol.... sounds like you have done what you can to fix the problem unless maybe the wastegate is sticking..... no leaks, boost controller doesnt help or hurt the problem, wastegate is newer... are you sure you arent leaking ? sorry i couldnt help

 

I think I'm going to try hooking up the MBC another way and see if it helps. right now I just have the WG signal line going to the bottom port on the Tial, the other way uses both top and bottom ports to controll boost. I guess its worth a shot.