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E78 A16LET Opel/Vauxhall 1.6 GT25 turbo fueling, timing and tq limits

Practical Reflash Tuning

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Hey guys, first time starting a topic and i hope this awesome community can help.

We have a opel astra J 1.6T with a A16LET Motor and E78 ECM.


- GT25 turbo

- 100% larger intercooler over stock

- Stock MAF (have a larger one not fitted yet)

- Stock injectors (Have bosch 440cc injectors not fitted yet)

- Stock in tank fuel pump (have an upgraded on as well not fitted)

- 63mm turbo back exhaust

- Forged pistons, rods, ARP rod bolts and head bolts, race bearings (motor run in and running sweet)

- GFB Gfroce 3 electronic boost controller

- Stock plugs gapped to 0.58mm

- CoolBoost Dual Nozzle water meth kit (not active yet until I figure out the tuning on this ecu)

- Other things like upgraded clutch tyres etc not important for this.

I have started by adjusting TQ limits to name a few:

Torque management > General:

- Peak Torque (set to 800nm)

- Brake TQ limit (Maxed out)

- Overboost limit (values are in NM so set to 800nm once again)

- Transmission, Axle and propshafts (maxed out)

Torque Management > Driver Demand > Map A - normal

- Driver demand at 100% throttle pedal (set to 800nm)

Torque Management > SC/TC Boost Control

- Boost Max Limit (320KPA)

- knock airmax from 1700 to 6500 at 0 knock retard column (1.10)

Airflow > Pressure Control

- Throttle pressure drop min (0KPA

- Throttle pressure drop table ( All 0KPA on all blocks)

Airflow > turbocharger > Over Speed limits

- Over speed limit min (10.00G maxed out)

- Pressure Ratio max (10.00G maxed out)

- Pressure ratio max table Matching above values on all blocks

Airflow > turbocharger > Failure

- Base duty cycle 100% accross entire table.

Engine Diag DTC's

- Turbocharger overboost dtcs disabled

- Turbocharger underboost dtcs disabled

- Cats disabled

The goal with the torque limits is to raise them all higher than what we will ever achieve since we using the electronic boost controller, and then set one torque limiter slightly above the boost we end up with once done as an extra safety over and above the electronic boost controller.

Now the reason why I'm making this post is that I am uncertain of how to adjust WOT fueling on this ECU to add fuel and then also how can I see if I am maxing out the injectors? I can only log injector open milliseconds from what I can see, and also how can I see if I am running out of MAF.

Thanks, guys I hope someone can help me and any advice would be much appreciated.

What software are you using to make your tuning changes? If you can't log a IDC PID then you can calculate it from the injector pulse width. You can work out the cycle time by using the calculation 120/rpm. For example at 7000 rpm the cycle time is 120/7000 = 0.017 seconds or 17 milli seconds. If your injector pulse width is 15 ms then 15/17.14 = 87.5%

With the torque based ECUs you need to be quite careful with the torque tables and often it's important to make sure they are quite accurate compared to what the engine is producing, otherwise you can end up with a DTC and limp home mode. I've lined here to an HP Tuners article that covers some specifics on the E78 ECM and particularly the torque based operation - https://www.hptuners.com/help/vcm_editor_tuning_how_to_advanced_e78.htm

You should still have access to a power enrichment table that defines the equivalence ratio targets when in PE mode. This is where you make changes to your target AFR.