Ok, it's a long read and I am trying to include as much detail as possible. Please read and help! So I have been racking my brain for way longer than I would care to admit to, I've read probably hundreds of threads from all over the internet and still have no idea what is wrong with my car. Background info. R32 GTR engine swapped for R33 RB26 which had been built by Mercury Motorsport a few years ago and saw seldom use since then. Engine was running when it was removed from the previous owners vehicle. Sump and cradle were removed to sight internals. Bearings replaced with Cosworth items. Engine was installed into my car after receiving a few additional parts (see below) First start up was relatively smooth, built up oil pressure, cranked, started, coughed a bit, knock sensors were not in, this was on a Nistune ECU.
Car info before swap R32 GTR R32 RB26 GT2860R -7's Standard AFM's Siemens 610cc injectors Walbro 460LPH pump Turbosmart E-Boost street
Nistune ECU tuned by MRC Dyno New Parts R33 RB26 built by mercury motorsport (forged internals) Tomei 260deg 9.15mm lift cams Tomei valve springs Tomei cam gears (set to 0/0) Ross Harmonic Balancer
After the initial start up (which I believe this issue was still present, just masked by holding revs around 3k) the car was left for several months. Nothing significant changed. Battery was replaced, new fuel added, oil and fuel filters changed.
The Issue
The engine will crank, but either struggle to start or cough and die. Holding a constant throttle the engine will start, sit at approx 1,200rpm, cough a lot and then do one of two things. Either A. Start firing sporadically incl. firing so early you can hear it firing back into the plenum! or B. Randomly kick up it's revs, anywhere between 2,000 - 4,000rpm with no extra throttle input at all. Both of these scenarios usually result in me turning the car off which then results in a loud pressure release sound (nothing venting externally) and me crying quietly in a corner. Things I have tried Unplug AFM's = No Change. Resoldered AFM's = No change. Unplug 02 Sensors = No change. Replace Crank Angle Sensor = No change. Replace igniter module = No change. Rearrange coil packs = No change. Replace coil pack loom = No change.
Replace spark plugs = No change. Replace Nistune with Power FC = No change. Please. Help?