Where did things go wrong on the previous tune, and how far off were things? Well lets start with constants:
- Boost 24PSI on previous tune
- Boost 23PSI on ours
- Timing optimization on our tune lead to power gains onto boost
- Fuel pressure optimization lead to power gains on boost
- Previous tune ran 13.1-13.5 AFR on boost!!!
- Both were done on a built EJ257
- Both tunes were set for E70 (ours was flex-fuel)
- Both were accessport based Pro-tunes
- Both were done on MD-AWD500 Dyno’s
- Ours took 1/2 the time to complete
So, where did the previous tuner go wrong? Well, the didn’t account for dropping fuel pressure on a very high demand fuel system. The fuel injectors could more than cope with any and all the fueling demand, however the fuel pump was not up to par. Since fuel pressure was dropping, they decided to increase MAFv scaling to compensate for the change in fuel pressure. With our tune, the MAFv scaling stayed the same, we used the fuel pressure differential to compensate the injector opening. We ran less timing at peak torque, as the previous tune was past MBT. The reason our tune made less power at peak torque was due to the lack of over-fueling. We also elected to drop boost by 1 psi, to help mitigate heat soak of the intercooler.