Problem, either boost creep or greddy profec b-spec 2

[Jeff822]

Ok, i had my greddy boost controller installed last week and all the settings are as low as they can go right now, but heres the problem, my cars is boosting to 23+ psi and hitting a fuel cut! So is this the boost creep or something with the boost controller? Right now i have a 3 inch DP 3 inch exhaust and I know this is probably causing the boost creep if thats what it is, could i solve this by getting the evo III O2 sensor housing? or any 3 inch O2 sensor housing? Right now i am still on the stock T-25 so what O2 housings will fit my stock manifold that can stop the boost creep? oh how do you change the boost controller from KPAs to PSI? still cant figure it out, thanks

 

[kenamond]

Is the MBC the only thing you changed? If so, make sure you connected it correctly. Hooking it up wrong can do this. This would be alot cheaper than a new O2 housing I don't see how you could be creeping now if the only thing you did was add a MBC and set it to the lowest boost setting.

Check this thread and always listen to oldman You can also do a forum search using "mbc installation".

Here is another link. There seems to be two schools of thought as to where to tap in your boost/vaccuum source. Some use the BOV vaccuum line (which runs to the throttle body) while others take it off of the turbo compressor housing (read oldman's reasoning behind using the compressor housing in the first link).

And to convert kPa to psi, go to google.com and type "convert kPa to psi" without the quotes. Google will give you the straight conversion. Try "convert inches to mm" (without quotes). Nice feature!

So just multiply your kPa value by 0.145 to get psi.

 

[N1balla16]

The spec 2 was a tricky one for me. In the manual that came with it it tells you how to change to psi, because I know I had a issue with that to. It sounds like you are getting boost creep to me but I would still double check the hook up of the boost controller. Make sure the line off your wastegate is connected correctly and the line isn't broken anywhere. Also, look at the soleniod you installed for the spec 2. Make sure you have it hooked up for internal not external. For the 02 housing question, The O2 housing is between the turbo and the downpipe, not the manifold. Your best bet to fixing boost creep with your setup is to go ahead and port the O2 housing. Check vfaq, there is a good write up there on exactly what to do.

Robbie

 

[Jeff822]

Is the MBC the only thing you changed? If so, make sure you connected it correctly. Hooking it up wrong can do this. This would be alot cheaper than a new O2 housing I don't see how you could be creeping now if the only thing you did was add a MBC and set it to the lowest boost setting.

Check this thread and always listen to oldman You can also do a forum search using "mbc installation".

Here is another link. There seems to be two schools of thought as to where to tap in your boost/vaccuum source. Some use the BOV vaccuum line (which runs to the throttle body) while others take it off of the turbo compressor housing (read oldman's reasoning behind using the compressor housing in the first link).

And to convert kPa to psi, go to google.com and type "convert kPa to psi" without the quotes. Google will give you the straight conversion. Try "convert inches to mm" (without quotes). Nice feature!

So just multiply your kPa value by 0.145 to get psi.

I have the greddy electronic boost controller sorry for the mixup, thanks for the replies, also the boost controller was hooked up at my local performance shop.

 

[kenamond]

Your best bet to fixing boost creep with your setup is to go ahead and port the O2 housing. Check vfaq, there is a good write up there on exactly what to do.

If you're going to try porting to fix creep, I'd read up on it. From your profile it looks like you have the stock turbo, so you may need to focus on porting the turbine inlet (specifically, opening up the entrance to the wastegate inside the turbine housing inlet). Member "oldman" has several good threads on this including reasons why you don't necessarily fix the problem by porting your O2 housing.

You can also check if its boost creep by disconnecting the wastegate actuator arm and doing a test run. If you still see creep, then the air isn't making it out of the wastegate and is still driving the turbine wheel and causing the creep. By disconnecting the wastegate actuator arm, the wastegate flapper has nothing to hold it closed, and the exhaust gasses should be able to flow freely out the wastegate passage giving you little boost - a few psi. If it is creep, the gasses are "choosing" to go into the turbine wheel instead causing boost to increase and you'll still see creep even though there's an open wastegate. That's why properly porting the wastegate entrance inside the turbine housing intake fixes this problem; the gasses don't have to go around a 90-degree turn to get out through the wastegate.

Another fix for creep is to use an external wastegate (usually off of the #1 exhaust runner), but there are other issues there (engine bay temperatures, noise, etc.).

Basically, if you're convinced it's a creep issue, do your homework so you don't waste time and money.

 

[polonez]

I dont think its boost creep. I think your profec is hooked up wrong. Try bypassing it and run the line right to the wastegate and see if it creeps then. If it creeps, you have a creeping problem.. I suspect that if you hook it up directly to the wastegate bypassing the profec it wont boost that hi and stay around 8psi.

If you're going to try porting to fix creep, I'd read up on it. From your profile it looks like you have the stock turbo, so you may need to focus on porting the turbine inlet (specifically, opening up the entrance to the wastegate inside the turbine housing inlet). Member "oldman" has several good threads on this including reasons why you don't necessarily fix the problem by porting your O2 housing.

You can also check if its boost creep by disconnecting the wastegate actuator arm and doing a test run. If you still see creep, then the air isn't making it out of the wastegate and is still driving the turbine wheel and causing the creep. By disconnecting the wastegate actuator arm, the wastegate flapper has nothing to hold it closed, and the exhaust gasses should be able to flow freely out the wastegate passage giving you little boost - a few psi. If it is creep, the gasses are "choosing" to go into the turbine wheel instead causing boost to increase and you'll still see creep even though there's an open wastegate. That's why properly porting the wastegate entrance inside the turbine housing intake fixes this problem; the gasses don't have to go around a 90-degree turn to get out through the wastegate.

Another fix for creep is to use an external wastegate (usually off of the #1 exhaust runner), but there are other issues there (engine bay temperatures, noise, etc.).

Basically, if you're convinced it's a creep issue, do your homework so you don't waste time and money.

 

[diablos991]

I had the same problem when I installed my Greddy profec b-spec 2 boost controler.

First I would check the Sylenoid by connecting it directly to a power source and then grounding it and listening for a clicking noise. if it clicks then it is probably not your sylenoid. Next I would check the wiring harness connecting your head unit and your sylenoid. then I would check the vaccum lines. One should run between the sylenoid and the wastegate. and one should run from the sylenoid to the turbo housing.

My problem ended up being that I had spliced my Greddy type-s blow off valve into the vaccum line that ran from the sylenoid to the wastegate. I respliced it into the vaccum line that runs between the turbo housing and the sylenoid and I was golden.

Good luck.