Fucking A! ca18det mbc, anybody run one?

[shane_lxi]

Okay. Lol, this is pissing me off now. I bought a perrin boost controller. I've installed many a mbc in my time, but for some reason the one I put on my car wants to be a pain in the ass. I cut the vac line to my wg and put in the controller. It brought my boost up, but no matter if I open it all the way, or closed it all the way, it would still boost way to high (about 16psi) then cut off. I tried flipping it the other, maybe I put it in wrong? No, if I do it that way I cant adjust my boost up or down, it just runs factory pressure, 6-7psi. So I was thinking maybe I have my wg hooked up to a shitty vac source? If anyone is running a ca18det with a mbc, please tell me if I should use a different vac source! I am only trying to reach about 12psi. Thanks a bunch.

http://i67.photobucket.com/albums/h315/shane_lxi/mbc1.jpg
there is another nipple directly below the throttle body too, but it is a little smaller then the nipple i have the actuator connected to right now. The smaller nipple is blocked.
http://i67.photobucket.com/albums/h315/shane_lxi/mbc2.jpg

http://i67.photobucket.com/albums/h315/shane_lxi/mbc3.jpg

[originalsin]

i run my wastegate off one of the lines that runs behind the motor, the factory one.

wat kinda vac are you pulling at idle?

[shane_lxi]

I am running 16-18 vac at idle right now. I have the vac line behind the mani hooked up to my boost gauge, I suppose I could switch the two tomorrow and see what happens. Are you running an mbc on your ca18?

[Wykydtron]

The actuator line is suppose to be coming off of the charge piping before the throttle body, not after.

[shane_lxi]

Then I will move it :D. Thanks ed.

[shane_lxi]

Shit, swtiched it to the nipple right below the throttle body and still nothing has improved. Took it out for now, when the weather gets better I'll try and figure it out (110mph winds tonight :( )

[Arther3]

The actuator line is suppose to be coming off of the charge piping before the throttle body, not after.


could you explain why it makes a difference?

[kuramaya]

I dont see what the problem is as long as you have one Vac line to the Intake manifold and one to the acuator like my setup here:
http://img.photobucket.com/albums/v317/bjorkluv/IMG_3344.jpg

[shane_lxi]

Yeah. Mine is inline. I had a line running from my actuator to the intake side, and I just severed it and put the mbc inline. But it wont adjust, it just always boosts to 15psi before cutting off :P.

[yokotas13]

i have a line going from the chargepipe going to the TB, to the boost controller.

[shane_lxi]

Thanks for your replies. I'm going to try welding a nipple on my cold pipe next wednesday (sadly, my next day off :( ) and seing if that works better. If not, I'm just going to have to assume I have a faulty mbc, nothing else is working and I have tried every vaccuum port available :P. Does anyone on here run a mbc with their ca18 setup who might be able to help? I've gotten lots of help from the sr guys :D.

[originalsin]

The actuator line is suppose to be coming off of the charge piping before the throttle body, not after.

it comes off the back of the intake manifold from the factory

[shane_lxi]

They are running sr's too, so that might make a little difference as far as vacuum locations go too. I'll try using the source on the back of the engine too. I currently have my boost gauge on that. I tried it earlier, but with a tee on that line, so I'll just dedicate it to the mbc and see what happens :D.

[badboy6686]

dude i would say that the MBC is installed correctly the way that ended up with stock boost, then you need to adjust it until you have it right where you want it. If you install it and its pegging out your boost gauge then that's a clue that it is obviously backwards and not letting the wastegate get a signal. I wouldn't go through welding a new port for vacuum as i'm sure your source is more than adequate

[Wykydtron]

could you explain why it makes a difference?

BOV's, Boost Gauge and FPR use vacuum.

Wastegates (Internal/External) operate on pressure.

Both work, but why rob from a vacuum source?

[boosteds13]

BOV's, Boost Gauge and FPR use vacuum.

Wastegates (Internal/External) operate on pressure.

Both work, but why rob from a vacuum source?


I think what he's getting at is that it shouldn't affect the operation of the MBC.

To the original poster, I have my MBC hooked up to the same place you do and mine works fine. Try taking the MBC apart. On some, the spring binds up and gets stuck. Either that or they messed up and put too stiff of a spring in it.

[shane_lxi]

dude i would say that the MBC is installed correctly the way that ended up with stock boost, then you need to adjust it until you have it right where you want it. If you install it and its pegging out your boost gauge then that's a clue that it is obviously backwards and not letting the wastegate get a signal. I wouldn't go through welding a new port for vacuum as i'm sure your source is more than adequate
I have tried it on every single available vacuum port, flipped both ways, adjusted at what is supposed to be stock, at what should be less than stock, and what should be more then stock. Basically I have covered every scenario already. When I had it installed and it worked at stock boost, I tried adjusting it with no results. It actually seemed to spool a bit quicker, but my boost stayed at 6-7 psi. I have pretty much tried everything, including taking it apart (which the warranty says not to do :P ). I was thinking the mbc was faulty, but how many things could be wrong with it. idk, I'll try some more ish tomorrow.

[badboy6686]

You are over compliacting the situation, the MBC is faulty, replace it and it will work.

[Hugh]

I've had this happen with an MBC before, one from Turbosmart. It boosted max all the time, no matter what. It's a bad piece, and I got screwed on Ebay buying it used. (seller probably had the same exact trouble with it)

As far as vacuum source for boost goes, you should connect it to the hot pipe.. not the cold pipe. The compressor outlet or just after will give you the best response for boost control, making the turbo hit maximum boost faster and more dependably.

Many turbo setups (OEM and aftermarket) sense boost from directly out of the compressor outlet for this reason.

I have a nipple welded to my hot pipe that goes to my EBC for this.

[shane_lxi]

Spring was no good/too stiff. I actually pulled one out of an ink pen, and messed with it for a while. Works great now, sitting at 12psi with a 14psi spike. Not too bad, right about where I wanted to be :D. Thanks for the help. I thought spending $90 on a boost controller instead of $14 would be a good idea, lol. I guess I was mistaken :P. Stupid Perrin :P.