Category Archives: Tuning Blog

Turbo Cruze Tuning

I wrote the following for a forum reply in regards to a question on how you get more power out of the cruze 1.6 turbo motors, as time goes by I will update this page or add some new “blogs”.

The ecu in the Opel Astra / Cruze / Barina / Sonic range and pretty much all the new gm ecu modules are moving towards torque based ecu’s/calibrations.

Essentially what this means is that the throttle pedal is no longer directly in control of the throttle blade and there for how much power you make, Logically or behaviourily you think the more you push the throttle down, the more the throttle blade opens and therefore the car will make more power.

Now the pedal simply act’s as an input into the ecu as a torque request, Of which there are generally 2. Driver demand (based on accelerator pedal position and road speed or rpm), the other “torques” you need to know is engine output. The control algorithm adjusts engine output (via fuel delivery, throttle position, boost pressure & spark) until it matches driver demand.

How does it know how much torque the engine is making without measuring it -> simple, the ECU contains mathematical models and maps that calculate it based on known input conditions. If you know how much fuel & air is going in, and the engine RPM, and the status of the A/C compressor and alternator, and the amount of friction that the engine has under those conditions, the amount of torque output can be calculated.

Now for the “fuel talk” i’ll be a little less thorough.
The factory tune, tries to keep the car running at stoich (14.7afr) aka lambda 1 as much as possible, even under boost. this is great for fuel economy & emissions. bad for power and potentially engine parts if it’s ran hot for lengthy periods, which is what running at stoich does under boost. At cruise to light to moderate loads this is fine.

Now that we know heat kills engine parts, especially pistons and all that heat goes straight into the catalytic convertor after the turbo, which ironically requires a very high temperature to become efficient in burning out crap that we didnt burn in the combustion champer. we are now left with a potentially red hot steel chamber and to reduce/prevent this from going chernoble on the car they then calculate the temperature of the cat within the ecu. if it’s gets into a certain range it will enrichen the fuel. in our case down to 9AFR which is super duper rich. The purpose is obvious, more unburnt fuel to cool the cat down, but it kills power.

See where im going with this?

Timing wise, this is really simple. There are multiple tables that affect the overall amount of timing the engine commands, these are either based on knock feedback, air & water temp sensors, ethanol percentage or based on the commanded fuel enrichment. each table is setup in it’s own unique way, but not all of them are either used or require to be used. Just depends on how you want to calibrate the output at the end.

In conclusion, In stock form the tune for the cruze & opel 1.6t is woeful and im my opinion has not been calibrated correctly at all, it’s like someone was given a year to come up with a tune from scratch and then 2 weeks in just went fuck it. that’s good enough, but i guess that because they sell it as a “cheap” car they didnt want to spend too much engineering time on it.