So, I *think* this makes sense...??? I just recently picked up a practically brand new TD04 off of an 06 WRX to replace my aging (and failing) 02 TD04. I installed the turbo last weekend. All went very smoothly, I used new gaskets etc...but I imeadeatly noticed that I was hearing a lot of wastegate, way more than before, plus my boost was WAY down...I could only peak around 11 psi as opposed to my normal peak around 19 psi. I started checking for the obvious things first, no boost leaks...anywhere. Then I remembered that the previous owner of my car had told me when I bought it that he had adjusted the wastegate arm. AH HA! So, I checked my old 02 TD04 and matched the adjustment on the wastegate arm of the new turbo to it as best I could...Still nothing, same issues as before. The next step I took was adjusting the arm all the way tight, and then all the way loose...just to see if it would drastically change anything, and still no change, the wastegate was coming open under partial throttle. Much sooner than it should have been. This afternoon when I got home I pulled my old turbo out and was looking at the wastegate and noticed that it was very much different than the wastegate on the new turbo. The most noticeable difference was that the diaphram on the old wastegate felt much tighter than on the newer one. It wasn't seized up, it was just tighter. This seemed to coincide with the issues that I was having...the tension on the wastegate wasn't strong enough to keep it from opening too early. So, I decided to swap the old wastegate onto the new turbo...and voila...it fixed the problems. These are my two ideas as to what could be the cause. 1. My old wastegate is...well...old. The rubber in the diaphram isn't as supple as it used to be. Therefore it is tighter/stiffer...My car was tuned on the characteristics of old wastegate. Because my wastegate duty cycles were setup based on the mechanical characteristics of the old wastegate they did not match the mechanical characteristics of the newer (more supple) wastegate. 2. There is a difference in design between the 02 and 06 TD04. Can anyone shed some light on this for me?
Since posting, I have found out some more info. The wastegate on the 06-07 TD04 IS in fact different. So, there you go. Aside from that the car is running great again, no more burning oil, and the fresh turbo is definately preforming better!
Different spring. Probably because the 2.5 has different flow requirements. Side by side the wastgates look *almost* identical, there are a few small differences, but aside from that they look like they are the same.