Diverter Valve Failures
 

Hi Gents...My Turbo build is complete. Had some delays for the past several weeks chasing vacuum leak issues (real or perceived) during the tune process and then things really went sideways when the RPM would marginally increase when the throttle was released. This issue was eventually diagnosed as failing diverter valves (new Forged diverter valves had been installed as part of the build) and the OEM DV's were reinstalled and Walla! All problems disappeared and the heretofore drivability/throttle application issues were also resolved.

Just curious if anyone else has experienced DV failures and if so what your symptoms were (I am kind of kicking myself as I was the person who requested the Forged DV's when we put the build list together).

My car is being shipped back Thursday and I am really looking forward to some seat time.

Everything I've read is that the stock DVs work well and there is no reason to change them. Maybe if you are going for a much bigger build they make sense. Didn't you upgrade your turbos, too? Which ones did you get?

Kinda like headers, most everyone says the stock ones are pretty darn good unless you get into the 800+ or more HP builds..

when were your leaks apparent? idle?

The Forge pistons ones can cause all sorts of issues. They can get stuck in the cold weather, jam up in hot weather/temps, leak from the o-rings twisting around. I have always just run stock diaphragm style ones without issue.

Yes the Turbos were upgraded to Tial 68mm VTG...I also did headers, just well, because I wanted to but yes I agree the OEM exhaust headers would have worked fine. Sam at ByDesign said he has said seen some HP gains from Kline headers so I went with them for my headers...btw I also got the Kline Inconel exhaust, total weight, 15 lbs.

We had 3 or 4 leaks identified; some manifested themselves with rough idle and one was mid rpm ~4k rough throttle, then the last issue was RPM increase after the Go pedal was released. The leaks were throttle body hose, o ring in one of the diverter valves, a bolt screwed too far in one of the intercoolers that caused a loss of pressure and possibly a fuel regulator hose. Sam at ByDesign felt the failing diverter valves may have been contributing factors all along as once they were replaced with OEM DV's even his base tunes were almost perfect. The silver lining to the cloud is the car was thoroughly pressure tested multiple times.

Oh trust me....I have been dealing with a "leak" of some damn sort for months now. Ordering my oem valves now.

Agree, I previously used Forge DV's and returned to stock. OEM's are plastic whereas Forge are metal. IMO that's the only difference and contrary to popular belief they do not increase horsepower.

Rodeo, can you share which codes were present in your car?

Where did you order the Tial VTGs from? And did you upgrade your injectors also?

I also found part which is goes from back of the plenum...and then tees off to the AIR injection system and also controls the diverter valves. I wonder if when faulty is also causes leaks.

9A1-605-165-00

It is cheap enough to replace....so i think Io am going to replace as well.

I keep getting P2187 and P2189 CONSISTENTLY....but it is intermittent. Sometimes car is horrible to drive and others it is fine. Luck of the draw when it starts up....so it has to be some sort of valve failure (electrical at that).

Sam at ByDesign Automotive Group supplied the 68mm Tial Turbos...injectors are ID Bosche 1334cc.

The last drivability problem that was so vexing that was fixed by installing the OEM DV's was not throwing a code.

I have been there. When my VTG actuator rod was seized I would get no boost and also NO type of CEL.