Boost control problem on 50trim

[Mirian]

I have been trying to slowly tune my 50trim and have been having a problem with a boost spike. I have a dejon tool mbc. I had been running low boost~14psi and was getting a spike up to 20psi, I turned the boost up just a little trying to get into the normal range for the turbo and the spike when higher with the boost (16psi spike to 24psi). Could this be caused by a leak or is it a faulty mbc? Any clues would be greatly appreciated.

Mods: turbo,255,fpr,afc,650's,fmic,1gbov w/ leak kit, full exhaust/downpipe

 

[oldman]

Boost spike = boost initially shoots past the setting then immediately settles down to setting.

Boost creep = Boost initially hits the setting then slowly increases as rpm increases.

Which do you have?

 

[Mirian]

oldman--- It is definitely boost spike. The boost flies right up to 24 then settles down to 16.

 

[92awddsm]

How do you have the mbc hooked up? Is it tee'd into the bov line or run from the turbo outlet? If you run from the bov, try going off of the nipple on the compressor outlet and see if that helps. Also keep the vac hoses as short as possible for the mbc. The longer the hoses, the more likley you are to get boost spike.

 

[oldman]

oldman--- It is definitely boost spike. The boost flies right up to 24 then settles down to 16.

I hope you're not waiting for my answer as it has already been correctly answered.

Is it tee'd into the bov line or run from the turbo outlet? If you run from the bov, try going off of the nipple on the compressor outlet and see if that helps. Also keep the vac hoses as short as possible for the mbc.

Try this and let us know what happen.

 

[Mirian]

Hey, the mbc is hooked up to the bov vac line. Before I try changing the pressure source I am going to replace the mbc->wastegate line. I found that the tube was spliced with a little white plastic nipple. I will let you know the results.

 

[Mirian]

Well I replaced the mbc-wastegate hose(short as possible) and I am still getting a boost spike. On the other side I don't have a nipple on the compressor to connect to. I will add a little info that may help.

The leak stop kit adds another T into the bov vac line, so there are two T's in that line. The leak stop T is closer to the bov than the mbc T. I though I would add this info in. I hope all this isn't too confusing.

Thanks

 

[92awddsm]

Well I replaced the mbc-wastegate hose(short as possible) and I am still getting a boost spike. On the other side I don't have a nipple on the compressor to connect to. I will add a little info that may help.

The leak stop kit adds another T into the bov vac line, so there are two T's in that line. The leak stop T is closer to the bov than the mbc T. I though I would add this info in. I hope all this isn't too confusing.

Thanks

Which 50 trim did you get? Most every one I have seen have the nipple on the compressor housing, specially if it came with an internal wg.

Anyways, try capping off the nipple to the bov(leak stop, not the top nipple) and run the wg hose as close as possible to the intake manifold. If that doesnt help, remove the mbc and run the hose directly to the wg actuator. Let us know how those work and we will try to go from there.

 

[Mirian]

Which 50 trim did you get? Most every one I have seen have the nipple on the compressor housing, specially if it came with an internal wg.

Anyways, try capping off the nipple to the bov(leak stop, not the top nipple) and run the wg hose as close as possible to the intake manifold. If that doesnt help, remove the mbc and run the hose directly to the wg actuator. Let us know how those work and we will try to go from there.

The turbo is a garrett t04b from bull's eye

I will let you know about the other stuff

 

[Mirian]

Back again! I tried what you suggested and I am still getting a boost spike. Is there anything else I can try or am I SOL?

Results from what you suggested:
Still spike, but about 1psi lower. Also capping the leak stop nipple caused the bov to make a fluttering sound, not good.



Problem solved: adjusted wastegate actuator.