Quote:
Originally Posted by lop00
So long story short, according to you either Dinan Sport Tuner/JB+/Any 2 Sensor piggyback will provide inefficient power gains to the car that in the long-run will also have negative implications on the engine's lifespan?
|
Long answer short, yes.
1) In this case, IAT alone disqualify them.
2) Assuming IAT problem is solved with IC/Meth, you'll be then looking at a leaner AFR because there is no adjusting fueling to the increased boost. Pre cat o2 sensor will be constantly reporting lean and DME will be busy reacting by adjusting to STFT (short term fuel trim). Though I doubt a couple hard pulls is beyond DME's adjusting capability, a constantly adapting DME will make a less smooth power delivery. More importantly, DME is actually adjusting to a less optimal target (because it sees less boost than real), a richer mixture should've applied under higher boost to ensure less chance of detonation and lower EGT (Exhaust gas temperature).
3) Put leaner AFR aside for a while, you get to the messed up timing table, the very final stage where power output is dictated. With increased boost and leaner AFR, ignition timing should be retarded accordingly. That's a difficult mission for even a more sophisticated piggyback like jb4 and Dinantronics, let alone TMAP based ones which is incapable of touching it up at all. Granted, factory tune always leaves something on the table (which is why so many people get away with it with low factory boost N20/N55 application) and N55B30T0's factory tune has a richer AFR already thanks to higher boost target, you still are left with much less on the table with N55B30T0, something proven to be sensitive to or desperate for octane as a clear indication that ignition is close to its edge and engine is very much prone to detonation. Higher IAT and leaner fuel mixture just add to it. I believe that's what sometimes happen in mid-to-high rpm range and DME is reacting to it by pulling timing.
Ask any seasoned JB4 N55 guys who plays with TMAP based piggyback at 17psi or above. I bet he'd be laughing his ass off.
I've attach a data log with my friend's stock m2 running on jb4 map1 (sport tuner equivalence), who barely know what he is doing. It happened just today on highway where intercooler has plenty of flow at its disposal. Only it turns out, from a single run, IAT is rocketing and timing is falling to ground. You can't even tell if it's because of the IAT or detonation. And that's when most of time it doesn't even hit boost target, which is 19psi or so.