silvergray951

I thought I'd share some hard-won knowledge I gained on diagnosing (and hopefully soon correcting) boost loss in my 951.
The car was only making 8 PSI boost and so I hooked up an LED on the diagnostic port and (after a full throttle run) as expected got the 3-1 fault code indicating low boost (helpful )
Since I recently did the venturi delete and replaced all the vacuum hoses with high quality silicone (see pic), I was pretty sure it was not leaking there...
The wastegate outlet pipe remained cool at idle while the main pipe and the wastegate inlet pipe heated up so this did not seem to be the problem. Checked the TPS sensor and found the values were in the correct range when measured at the KLR control unit. Checked the blowoff valve, but when I pressurized the intake and sprayed soapy water onto the various junctions and components, I noticed that a huge amount of air was escaping from the top of the Cycling Valve, leaking around the electrical connector bayonet terminals! I was surprised by this since I replaced this component about 1 year ago. So, just wanted to encourage you guys to suspect this component if you notice any boost loss!

In order to fix this (and bypass the stock boost controls including the cycling valve), I want to get an EBC - looking at the Greddy PROFEC B-SPEC2 since I see you can get them new from someone on Ebay for $300 shipped...
http://cgi.ebay.com/ebaymotors/ws/eB...tem=7933933192
Anyone got a cheaper source or some reason to recommend against the B-SPEC2 or this vendor?
I have Guru chips, tuned for 15 psi, mostly stock engine.

pk951

I bought one not to long ago on EBAY buy it now price was 279$ not shipped add 15$ for shipping.

Works great for me.

the vender name was Dragperforance.

Sam Lin

If you're paying that much, get a used AVCR, it'll be under $300 and it's a better EBC.

Sam

pk951

I bought a used profec-b one last year did not work, so when you buy used you take your chances.

Granted the avcr has more whistles, and bells but it it has the same control valve.

dme

I've got the Profec B and it is rock solid.

Jeremy Himsel

It's nice to see someone use some troubleshooting skills. I had that same problem with a brand new cycling valve a few years ago. Since you can access those connections fairly easy, you can use some plastic epoxy to seal it back up (I've done it twice). I'm not sure that the small amount of air leaking from the CV will cause you to loose that much boost but it may very be. Good luck.

BTW, I have the AVC-R and once you get it set up it works great. It does look a bit too ricey for my particular taste but I keep it hidden.

Sam Lin

I've purchased a couple used EBCs now, all have worked great - just shop carefully, look at the pics, ask the seller questions, take note of location (cold/wet areas are more likely to have issue).

Control valve is not the only thing that matters - Blitz DSBC use the same control valve as their SBC-iD, but a DSBC won't outperform an AVCR whereas the SBC clearly will. The logic control behind the actual solenoid plays a very large part, which is also the reason I'm recommending that he spend the money on an AVCR and not a Profec.

Sam

silvergray951

That is a great point - thinking about this some more, I wonder if I have another leak/problem to address. A (smallish) leak at the cycling valve would actually bleed pressure off the wastegate actuating line causing increased boost ... is that right?

I did consider the AVC-R but decided against it for 2 reasons - the added cost and the installation complexity (I think it needs extensive integration with the DME in order to opperate correctly .. at least Revs and speed input).

Jeremy Himsel

The CV leak could be causing it to operate inappropriatly by immediatly diverting air to the wg causing it to open. The WG itself could be just opening early and shimming might help a bit. Try clamping the WG line an carefully see what the boost does. I also usually find the same size leak at the idle air control motor when I pressurize the intake.

The AVC-R only required hooking up 3 aditional wires over a standard controller (Rpm,Tps, Speed signal). There's so many of us running it you'll have plenty of help if you change your mind. It's really not as complex as it looks or as people make it out to be. The biggest gripe I had was the manual was useless.