I recently installed a Greddy Profec B Spec II and I am having some issues. Wastegate is 46mm Tial w/a .9bar (13.053psi) spring. I have the EBC setup to run in dualport mode with COM connected to the top port and NC teed into the line running to the side port.

The problem is that I cannot increase boost beyond ~14.2 psi in 3rd or 4th gear. I have increased the SET from 0% to 100%. Chips are mapped for 15-16psi, so this what I am trying to hit. I have an Autometer gauge and it reads the same boost as the Profec, so I know that the Profec is receiving the air signal.

I have connected the solenoid valve to a 12v source and it cycles, so I assume that it is operating correctly. Beyond that, I am at a loss. I have checked the wire from the solenoid to the boost valve and it seems fine. Had no problems boosting to 16psi with an MBC.

Any thoughts/suggestions? Is there anyone out there that is running there Spec II in single port mode? TIA

 

why are you running it in single port mode? why not dual port?

 

Right now it is setup to run dual port. I asked the question at the bottom more out of curiosity than anything else. Since dual port is not working for me, I was thinking about giving single port a try.

One thing I did find last night is one of the wires pulled out of the back of one of the connectors to the solenoid rather easily. I stripped some more of the insulation off the end of it and re-inserted it, but I haven't had time to try it out yet. Needless to say, I am not too impressed with these connectors or the person/machine that put them together. Cheap connectors are a crappy way to cut cost on electrical components.

 

did you make sure you are using the right ports on the solenoid? And the one port must be vented to the atm (no plug in it)

 

I am following the instructions in the manual for external wastegates. Com to the top port and NC to teed to the side port. Wastegate is a 46mm Tial.

 

I've run the same EBC with a 0.6 bar spring in a Tial 38 and still managed to have a flat boost curve at 1.4 bar. At 1.7 bar it fluctuated a bit though

But it's not hooked up at the moment so I can't give you any settings, sorry.

 

Just to clarify, the teeded hose to the side port is hooked up to the turbo-intercooler pressure pipe?

 

Correct, from the same location as the stock banjo bolt.

 

As a preface, I am an absolute newbie to 951's.

I just bought an '88 Turbo S with stock turbo, Vitesse MAF & chip (KLR eliminated), Lindsey Racing 944-TBE-1 boost enhancer, Tial 38mm wastegate, 3" FabSpeed exhaust. The GReddy PRofec B-specII was already installed and I was told it was set to "1.5 bars" boost (and was recommended to me to leave it as-is).

I had the car on the track at Road America the past two days and found that after a brief period of pulling hard (e.g floored in 4th gear uphill on the front straight or accelerating hard on the flat in 3rd gear) at presumably max boost, power would suddenly (shudderingly) drop away and then come back up. The boost gauge read about 16 pounds when I quickly glanced at it a couple times when this happened.

My instructor (driver of a seriously modified 944 s2) was in the car when this was happening and he described it to a 951 tuner there (who had to leave before I could talk with him). The tuner thought it sounded like an over-boost situation.

Anyone have any insights into tuning the GReddy to eliminate this (if the controller is capable of preventing it)? It was the car's only flaw over the two track days and the car deserves better than to be beaten up that way.

Thanks for any ideas!

 

First of all welcome to Rennlist!

I did solve the problem at the beginning of this thread by hardwiring my wires from the head unit to the solenoid with wire nuts. Its amazing what a good electrical connection can do for you.

But back to your issue. This model of boost controller has built in overboost protection. It is supposed to kick in when the overboost level (specified by you) is reached. Once reached, the controller lowers the boost by X% (also specified by you). Not sure if you have the original manual, but you can get it from Greddy's site here (http://www.greddy.com/img/PHP/products/pdf/682.pdf). However, when it kicks in, the screen flashes to red and it is supposed to have an audible alarm. So, if you didn't hear/see anything different on the unit, this may not be your problem, or it may not be functioning correctly. But, from your description, it sounds like this could be what is happening. With your setup, I would think that the factory overboost protection (Cycling Valve) has already been bypassed and is not related to your issue.

I would suggest going through the settings to see how it is setup as a good place to start.

 

88951er, Welcome to the RennList and congratulations on your new car. Running 1.5bar (22psi) boost on a K26 is not a good idea. Hopefully you were running race gas! If you email me directly the name of your car's previous owner, I might have some data to share with you.

 

If your running a lindsey boost enhancer as well as the profec b then I would start by removing the LBE and adjusting the profec from there.