bucking when going into boost

[Kingtal0n]

The reason you want copper plugs is because they are cheap.
The BKR7ES should be a $2/each plug
gap them down for getting your engine on the right track.

Always use new plugs when diagnosing issues so you can inspect the plugs to determine what sort of issues you are facing (oil/fuel/wet/dry/whatever)

Keep a second and third set of cheap plugs set aside brand new plugs for replacing when you fix some issues, to get a new read on the situation.


Maf voltage looks about correct. 4.5V is approx 450rwhp so 500hp or 520bhp or so at full 4.5 to 5volts which you are probably very far from so 3 to 3.5v is fine

Fuel pressure regulator is adjustable? Set to desired pressure around 43-44psi while engine is off (no line connected = engine off).
If regulator is OEM and the pressure is high,
A. replace fuel filter (use 300zx filter)
B. possible clog in return line
C. possible bad regulator (Never seen one though)
D. possible overpowering the OEM rail (are you using a walbro 450 or some huge pump?)
E. possible bad fuel pressure gauge

In any case, 50psi of pressure is not that much extra pressure over 44psi. It should not make a big difference (5% fuel adjustments?) But it IS a diagnostic concern and should be fixed.


So again, it goes
Maf -> ecu -> injectors

Thus, if there are NO boost leaks, and the maf sensor is CORRECT, and FUNCTIONAL, and placement is PROPER,

The only thing left is tuning wise (injector size & delay setting mostly, maf selection), & wiring related. The ECU must control the injectors based on what it see from the maf sensor. For ROM TUNES I always use a SAFC to dial in the exact a/f ratios as needed because ROM tunes vary from car to car. This is due to differences in the various AGED components i.e. the maf sensor on one car will be 3.2v the other will be 3.4v for example, it needs dialing in using an SAFC to achieve proper a/f ratios. Another example, 550/740/etc...cc injectors vary greatly in lag time (latency delay) and system voltages (one car is 14.4v the next is 13.8v etc) thus the injectors are ALWAYS a variable.