Hello all. I've been tuning my cruze on my own with some of your guys advice. I was wanting to see if i could upload my tune and my data logs and you guys could tell me what's going on. Currently have zzp CAI, Catless downpipe and Catless midpipe. Its showing i'm getting 23lbs of boost at like 3,300ish RPM's. When I start car in the mornings or after its been sitting awhile, it wants to die. After trying to restart twice it runs just fine. Just kind of surgy.
The logs show the car is running extremely lean.
It is dying at startup because the intake, downpipe, and midpipe have changed the ECM's airflow model so much that the engine cannot run.
It is only able to run after achieving closed loop, where the ECM uses feedback from the oxygen sensors to make the extreme corrections necessary to keep the engine running.
Because the car was not designed to run solely on these compensations, this causes surging and other drivability issues.
You need to modify the ECM's airflow model to compensate for the changes you made to the intake and exhaust plumbing.
There are two ways tuners do this:
The simplest way is to force the ECM to use only MAF sensor for airflow, then adjusting the MAF sensor curve until long term fuel trims are within +/- 10% under all driving conditions.
I do not recommend this method as MAF sensors do not like turbulent airflow, which aftermarket plumbing intentionally creates for audible intake noise.
The other method is to adjust the VE coefficients under Airflow -> Speed Density, in a process called "Speed Density Tuning".
Numerous videos exist explaining the process, but it is time consuming and relies on reliable feedback from the oxygen sensor. A proper EGO sensor, commonly referred to as a "wideband sensor" is recommended for proper tuning, and ideally access to a dynometer to achieve consistent results safely.
But before you do this, you need to also verify your entire PCV system has been replaced with updated parts (Cruze/Sonics are notorious for this, you need to replace the integrated assemblies: Intake Manifold, Valve cover, and PCV hose), as those can cause strange hard-to-troubleshoot drivability issues that make it harder to tune.
If you are in a parking lot and need to get it running right now, multiplying the entire VE Constants table (Airflow -> Speed Density -> VE Coefficients: Constant) by 1.15 should be enough of a correction to start somewhat normally cold.
The cruze is a difficult, unforgiving car to tune, and I do not recommend modifications for someone just starting out.
I recommend removing the intake and exhaust modifications, returning to a stock configuration until you become comfortable with Speed Density tuning, or until you find someone who can tune it for you.
You can get good performance improvements with the stock equipment alone.
I have adjusted your attached tune with some common, easy changes to a stock configuration to improve drivability.
I am assuming the tune you attached is stock + changes to knock airmass and driver demand.
If you made changes to other tables, such as speed density, do not flash the attached tune because I have not accounted for those changes.
Safety:
These attempt to protect the cruze's wastegate housing, and also the cylinder head should the engine overheat.
As a reminder, the cruze is notorious for coolant leaks - you should check your coolant level daily and investigate leaks early. For your year, the most common source of leaks is the reservoir, coolant outlet, and water pump. Early cruzes were much worse.
The coolant temperature gauge does not budge unless temperatures are over 239F, giving you very little time to react,
making it very easy to severely overheat the engine.
- Power Enrichment: Power enrichment from a factory Sonic RS + additional enrichment for low RPM boost
- Temperature Control: Heavy enrichment when overheating is imminent
- Spark Advance ECT Adder: Heavy spark retard when overheating is imminent
- Knock Airmass: Reduce Max Airmass to factory levels when knock retard greater than 3 degrees is present
- Fans: Aggressively ramp fan when temperatures approach 230F when the eco temp (221F) setpoint is targeted
- Fans: Aggressively ramp fan when temperatures approach 213F when the low temp (194F) setpoint is targeted
Performance:
These settings disable overspeed limiting to prevent "boost limp". This is safe to do on a stock turbocharger.
- Overspeed Limit Min: Set to 3.00G
- Pressure Ratio Max: Set to 3.25
- Surge Limit: Incrase by 1.25x
You already raised Driver Demand and Knock Airmass to achieve maximum boost the factory turbocharger can deliver (approximately 23psi). The fact you can achieve this without touching the Wastegate DC table means your wastegate housing is probably not cracked, and your PCV system is probably functioning properly.
Transmission:
I made conservative adjustments to give a more sporty feel:
- 2->3 and 3->4 shifts after 44% throttle
- 4->5 shift delayed until throttle is below 50%
- 5->6 delayed until throttle is below 44%
- shift speed for 1->2, 2->3, and 3->4 shifts increased under high torque.
- Reduced torque converter slip speed for all gears.
TL;DR:
- Put the stock intake and exhaust back on.
- Flash the attached tune UNLESS you made additional changes outside driver demand and knock airmass.
- If there is weirdness, flash to stock and report back.
- Enjoy, remembering to check your coolant regularly, and change your transmission fluid every 30k miles.
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