I have a stock redtop in my 240 basic upgrades (FMIC, exhaust etc), nothing special (See the link in my sig for full details) However, the engine has been giving me some grief ever since I installed it. It runs pretty good while cold then after a few minutes of driving (sometimes 30 seconds, some times 10 minutes) it will start acting up and have major hesitation whenever I get into boost between about 2000-5000 rpm.
I have checked codes and originally had a knock sensor code. I replaced that and now I have the 55 code. All is good.
While working with a mechanic friend of mine, we discovered while having the car hooked up via OBD, that the ignition timing appears to be pretty normal under load while boosting when the engine is running ok. However, when the engine starts acting up and hesitating, the timing is retarding to -6 degrees at worst and sometimes jumps all over the place.
We suspected the CAS but after looking at it on an oscilloscope while driving it appeared to be sending a normal signal from what we could tell. We have also metered out the coil packs, injectors and coolant sensor and all appear to be well within specs according to the FSM. There is also plenty of fuel pressure and the regulator appears to be working fine.
We are running out of ideas and any input would be much appreciated!