Hi guys.
Quick review. Stock as a rock 2001 R34GTT Tiptronic Sedan. Only engine mods CES 3" Turbo Back exhaust with Split Dump HPC coated, hiflow cat and Twin tip muffler. Also has a K&N Panel Filter.
Before zorst upgrade, car ran stock boost, about 7psi. After zorst upgrade, car runs 12psi. Car seem to run perfectly fine. No spikes in boost or loss of boost, irrespective of my driving style.
Okay, now for the problem. Had the car in for a 80K service. (reputable company I shall leave unnamed for now) He said the timing was out by almost 10deg. So he adjusted appropriately. Driving home, boosted a few times, then the car dropped boost and ended up running 7psi. Restart the car, back to 12psi, then boosted a few times and bam back to 7psi.
Have been back to the mechanics a few times, but they are struggling to find the fault. No ECU faults showing, however they are getting an ABS/TCS computer fault showing up. Error code 58 from memory. He seems to think it is something to do with throttle/valve control?? However even after clearing this error code, the problem still reoccured but this time without the error code.
My personal thoughts are that the boost is running too high for stock ECU and thus causing the car to go into a type of limp mode.
My question is, how the hell do I wind back boost when the stock boost after zorst upgrade is sitting at 12psi?? I want to get back to around 10psi. I have tried turbosmart boost controller, but all that did was take the solenoid out of the equation and still left the boost at 12psi.
Any suggestion or thoughts are very much appreciated. Sorry about the epic story!!