GTR/370Z Cranking Fueling

Owned by Lucan Hetherington
Mar 28, 2022
3 min read

Cranking and starting performance on Nissans (GTR/370Z/VR30) fllow a strategy usig open time specified for different phase of the cranking process. It appears that the cranking setup is broken into 4 different phases

  1. Default setting no information known yet

  2. Intitial engine rotation (nothing is synced yet)

  3. Half Sync where it knows the crank position but not which phase of the cyle its on

  4. Full Sync where it knows the position of the crank fully

These phases of cranking have set injection and spark outputs depending on were it is in the phases of syncing up. The information that Ecutek have found on what actions are taken when it moves tough the different phases is as follows,

Phase 1 (initial phase)

Cranking Initial = (not a cranking map per say) Initial guess at cranking PW when no other info is known 

Phase 1 (rotating but not synced)

Cranking Step 1 = Initial fuel pulse on all injectors when ECU detects engine is turning 

 

Phase 2 (half Synced)

Cranking Step 2 = Initial fuel pulse in batch mode (2 cylinders) when engine is half synchronised (ecu knows crank angle but not phase) 

 

Phase 3 (fully Synced)

Cranking Step 3 = First fuel pulse on cylinder events 3, 4 and 5 as engine is fully synchronised At this point no spark has yet occurred


First spark on cylinder that was fuelled on Cranking step 1 

 

 


Cranking Step 5 = First fuel pulse on 6th cylinder event after 1 full cycle, engine is now fully synched

 

 

 

 

Cranking Step 4 = cranking after 1st full cycle.
Yes 5 then 4!

 

Global Multipliers

There are RPM based mutlipliers to help itmove from cranking to running which reduce the pulsewidth back to normal as the RPM increases.

 

After Start AFR targets

An adjustment to the target AFR after cranking has finished depending on timers and closed loop operation is employed on GTR, these maps are caled “After Start AFR Comp ECT 1 & 2” and can sometimes make the fuel delivered after start too rich (with ethanol Blends) so can be adjusted to suit the vehicle.