987.2 Cayman/Boxster S

987.2 Cayman R

987.2 Boxster Spyder

Tuning Guide and Table Definitions

This tuning guide is broken into the basic components of tuning a Porsche 987.2 3.4L and the tables associated with each of these components. The guide outlines basic tuning strategies and defines tables for each major tuning category, such as cam timing, fueling, and ignition timing.

Step 1 – What is the mechanical configuration of the vehicle?

The first step in tuning a Porsche 987.2 3.4L is choosing a COBB Tuning Off-The-Shelf (OTS) calibration that most closely matches the mechanical components and modifications of the vehicle to be tuned

The Stage1 calibrations are designed for vehicles with no aftermarket parts at all. The Stage2 calibrations, upon release, are designed for vehicles with upgraded headers. This major difference in configuration impacts the pumping efficiency of the motor and critically impacts most major aspects of tuning.

Step 2 – What fuel is the vehicle using?

Note that COBB Tuning offers calibrations for different fuel. Higher octane ratings indicate higher quality fuel that burns more slowly and can support higher cylinder pressure prior to detonation. This difference in fuel will determine how the car is tuned. Higher octane fuels support more ignition timing and leaner air-to-fuel mixtures compared to lower octane. Using a map designed for high octane with low octane fuels can result in damage to the motor.

Step 3 – What type of air intake is on the vehicle?

The 987.2 3.4L utilizes a predicted mass airflow, but does not use actual MAF (Mass Air Flow) sensors. It uses airflow calculations to estimate engine mass air flow. Changing intakes will require some small changes to the calibration, but because the car does not have MAF's it is not as important to rescale the MAF based on intake pipe diameter change. The 987.2 3.4L does use the airflow calculations to limit throttle so making changes to calculated airflow tables is critical to making the car run correctly when drastically increasing airflow.

Step 4 – Calibration refinement on a chassis dynamometer.

A: Perform initial testing under safe conditions.

After selecting the most appropriate initial calibration, prepare to test and refine the calibration on a chassis dynamometer. When creating a custom tune, it is best to begin testing under safe conditions by lowering ignition timing and richening the fuel mixture. 

B: Connect the Accesstuner software to the Accessport equipped 987.2 3.4L

Open the selected starting calibration in the Accesstuner software then configure the software to connect to your vehicle. Attach the OBDII connector to the vehicle and, to your Accessport (if applicable), then connect the associated USB cable to your computer. Press "Ctrl+F" to configure the program. Select the directory in which to store your data logs under the "Logging" tab.

C: Log critical engine parameters while testing.

Accesstuner software allows the user to sample and record critical engine parameters including sensor information and commanded engine function. Open Accesstuner and load the calibration currently flashed to the vehicle. Attach the OBDII cable to the vehicle and the computer. Press "Ctrl+F" to configure the logged parameters in the "Log List" tab, and those displayed in the Accesstuner "Dashboard" through the "Gauge List" tab. The Dashboard, a screen that reports active engine and sensor parameters, can be accessed by pressing "Ctrl+B." It is critical to actively monitor the condition of the motor during tuning and this screen is the single best way to do so. These data monitors allow the tuner to determine if a calibration is performing correctly. Accurate and deliberate assessment of logged parameters is the only way to avoid conditions that may damage the motor.

*Items are separated into blocks (G01, G0F, etc..).  Limiting the number of blocks will increase sample frequency.  Whether one item in a block is queried or all of them the logging speed will not change so try and group as many items in as few blocks as possible.  This is why you may notice duplicates of some monitors. EX. Choosing (G02) Engine Speed and (G02) Oil Pressure will log faster than selecting (G27) Engine Speed and (G02) Oil Pressure.  

D: Tuning for appropriate Air to Fuel Ratios (Lambda)

The ideal air to fuel ratio (AFR) depends upon fuel quality, engine design, fueling model (port injection, DISI, diesel, etc.), heat exchanging abilities, and other variables. Higher octane fuels are more stable at higher cylinder pressures, and are more resistant to pre-ignition. Leaner AFRs can produce higher power, but also create more heat that may lead to unsafe pre-ignition. Lower octane fuels, such as 91(95 RON) and ACN91 (Arizona, California and Nevada 91 octane), are less resistant to detonation and require a richer (fewer parts air per parts fuel) AFR for safer operation. Richer AFRs produces less heat, protect against detonation due to a cooling effect of the excess fuel, and usually produce less power. We have found that the 987.2 3.4L motor is tuned on the leaner side from Porsche. After some initial testing we have found that just by richening the fuel target, the car picked up power. So we suggest a target AFR of 12.2:1 or a lambda of around .83 as a good starting point.

Air to fuel ratios for these vehicles are directly impacted by several tables. The Porsche fuel control system operates a closed loop control strategy. This means that the car runs a set of wideband air fuel sensors, and is constantly adjusting the fuel targets based on a collection of variables. The fuel target under wide open throttle is dictated by the Basic Lambda Setpoint maps as well as Lambda Full Load Enrichment and Lambda Full Load Enrichment for Sport Mode. Setting a target in this table will yield the desired Air Fuel desired, as long as some of the others conditions are correct.

A fuel mixture that is too lean will contribute to uncontrolled combustion, excessive heat, detonation and possible engine damage. The objective is to run the car at the richest air to fuel mixture possible that does not sacrifice power. Ultimately, the best air to fuel can only be determined in concert with changes to ignition timing. For example, some cases a comparatively rich air to fuel mixture can be run with more ignition timing than a leaner mixture. This combination may produce higher power than a lean mixture with less ignition timing. Generally speaking, the air to fuel and ignition timing combination that produces the best power while minimizing heat is the desired calibration. Of course, this ideal is not limited to ignition timing and fuel, but is also a balance with that and variable cam timing.

E: Tuning Ignition Timing

The ignition control strategy in the Porsche 987.2 3.4L is very dynamic and has a lot of contributing variables to determine the overall ignition timing value. Since the car is always trying best to calculate an overall best efficiency, it does this for ignition timing by using the Absolute Calibration for Reference Ignition Angle Due to Valve Overlap and using a target lambda (ʎ) =1 as a base for the efficiency. Additive corrections get made and it forms a variable in the ECU that is "optimal timing." This is the basis for all the ignition calculations in the car. The Porsche uses a strategy of two states of cam timing as well. These points will dictate which of the ignition timing maps are used and when. The actual ignition timing uses some additional variables and then comes to the conclusion of ignition timing based on the difference between Absolute Calibration for Reference Ignition Angle Due to Valve Overlap and Calibration for Reference Ignition Angle Die to Valve Overlap. Ignition Timing changes will need to be made in the Calibration for Reference Ignition Angle Due to Valve Overlap tables to start, as these are the basic tables that will reflect changes made. The first 4 tables are the main tables being used in WOT (Calibration for Reference Ignition Angle Due to Valve Overlap, 0-0 thru 0-3).  Do not set these tables the same.  Simply raise them all equally in the same load/rpm areas.  

F: Knock Control System

The knock control strategy on the Porsche 987.2 3.4L is very complicated and uses individual cylinder knock control to make changes to the ignition timing at all times. The system is very sensitive and thus almost always has some sort of feedback. You can monitor knock retard and ignition correction in each cylinder. This is the best way to check for detonation, and to ensure a safe running vehicle. The closer to 0 the better, but if it sways into the negatives (-1 and below) this is the car registering detonation. Since the car is very dynamic it is made to be sensitive. If you are getting values past -6 you will want to try and lower ignition timing, or add more fuel to and see if you can bring the values closer to 0. Running a race fuel will also help in getting the knock control values closer to zero.

If running built engines you can change the knock detection thresholds in the software. By raising these tables you are de-sensitizing the knock control system. THIS SHOULD BE DONE WITH GREAT CARE AS DOING THIS CAN RESULT IN ENGINE DAMAGE AS KNOCK CONTROL BECOMES LESS ACTIVE!!

Generally speaking, higher ignition timing supports higher torque and greater power. However, ignition timing should be increased with great caution. Higher timing yields are limited by fuel quality and the mechanical limitations of the motor due to higher cylinder pressure. Too much timing will produce knock sums when fuel quality is the limiting factor. When fuel quality is high, ignition timing should ONLY be added when its addition produces a substantive increase in torque and power. If increased timing does not increase torque, the extra cylinder pressure is simply producing unnecessary stress on engine components.

G: Porsche Torque Control Strategy

The Porsche 987.2 3.4L DI uses torque control to influence how the car behaves on power and off power. This system uses input from a wide variety of internal and external sensors to dictate how the car reacts in certain conditions. This is dynamic and varies based on conditions, temperatures etc.

This ECU uses various methods to control torque output, such as closing the throttle plate when the car overshoots a target torque table. So you will always want to monitor throttle plate opening as it is a way for the car to lower the torque output. Other methods include lowering ignition timing, or changing air fuel ratios. So you want to be sure that the car is optimally calibrated in all conditions.

A very important control system for torque is calculated airflow by the ECU. The ECU will limit throttle based upon the calculated airflow the car is seeing. There are three tables that are very important to being able to effectively control torque based on airflow. They are Maximum Intake Air of the Engine at Standardized Ambient Pressure, Maximum Intake Air of the Engine at Standardized Ambient Pressure Different Valve Lifts 0 and 1.

Since the ECU does not have mass air flow sensors it uses estimated airflow. You can raise the tables mentioned in the paragraph above if you are finding that your monitored predicted air mass is passing the values set in these tables and causing the throttles to close.

H: Tuning Variable Cam Timing (Vario-Cam Plus)

Porsche uses a variable cam timing system that changes cam duration at different engine speeds, but with Vario-Cam it also changes the valve lift dependent on cam phasing. This provides very good efficiency in all driving ranges as it can change lift using hydraulic tappets with a type of attachment pin. There are 3 lobes on the cam and the center is the "slow lift" the outer 2 lobes are the fast lift and pertain more to making more power and a higher lift. This helps to make more power through the power band. The cam timing can be changed in the software. In order to be see results from this type of tuning a chassis or engine dynamometer is required.

I: Speed Density/ Estimated Mass Flow

The Porsche 987.2 3.4L does not use MAF sensors, but instead uses calculated airflow using variables calculated from sensors and other parameters in the ECU. It then uses these types of calculations to estimate the amount of airflow entering the motor based on the engine displacement and a slew of other variables related to air flow, temperature and barometric pressure. 
If stroking a motor, the software allows you to enter the new displacement of the engine if changed, and the car will make changes to the mass flow calculations to allow for the displacement change. Tuning will still need to be performed, but the calculation will be as correct as possible. This table is called Engine Displacement.

The SDI3 ECU also uses heavy torque targeting methods. This target is very important, and being too far over or under can cause the car to have errors.

J: Integrating all tuning parameters for the ideal calibration

The ideal calibration for your Porsche 987.2 is a combination of all major tuning areas outlined above. Generally speaking, the Porsche 987.2 3.4L will make the most power when it runs a lean AFR with the maximum amount of ignition timing allowed by the ECU without detonating. However, the theoretical ideal of 12.5:1 air to fuel ratio and high ignition timing is not realistic for all configurations and fuels. Calibrations should be thoroughly tested on a chassis dynamometer, where the impact of tuning is easily measured.  This is to determine if they are ideal for the vehicle, its mechanical components, and its fuel. For example, addition of ignition timing that does not result in increased torque is not ideal because it produces additional stress on engine components without a perceivable benefit. The same is true with air to fuel ratio. If the vehicle can operate at a richer air to fuel ratio without losing power, it is ideal to do so in most conditions. For a basic idea of ideal tuning parameters for your fuel type and mechanical configuration, examine the COBB OTS map notes.

K: Precautions:

Fuel – The stock fuel system in the 987.2 3.4L is Direct Injection. Therefore the fueling the car is injected directly into the cylinder at very high fuel pressures to help atomize the fuel. There are limitations to these systems, so you will want to measure fuel pressure to see if you are having any issues with fuel delivery if you are significantly increasing airflow. 

Folder: Airflow Tables

Correction Factor for the Maximum Intake Air Depending on the Intake Air Temperature

Table Description – This is a modifier table based on intake air temperature.

Tuning Tips – This table is set to 1 from the factory.  Lowering this value can cause throttle closures at higher intake temps or RPM if that is desired. 

Maximum Intake Air of the Engine at Standardized Ambient Pressure

Table Description – This is a maximum airflow table based on calculated airflow, in normal mode.

Tuning Tips – Raise this table when adding parts that increase airflow. 

Maximum Intake Air of the Engine at Standardized Ambient Pressure for Different Valve Lifts 0 and 1

Table Description – This is a maximum airflow table based on calculated airflow.

Tuning Tips – Raise this table when adding parts that increase airflow.

Folder: Cam Timing

Inlet Camshaft Position Setpoint at High Temperature Level 0-0 thru 3-1

Table Description- Degrees BTDC (before top dead center) that the intake cam opens and closes.

Tuning Tips- Modify this table to try and achieve optimum cylinder filling and to help increase volumetric efficiency. Best modified on a chassis or engine dyno so you can measure results. These are based on varying conditions and in normal mode, NOT sport.

Inlet Camshaft Position Setpoint at High Temperature Level for Sport Mode 0-0 thru 3-1

Table Description- Degrees BTDC (before top dead center) that the intake cam opens and closes.

Tuning Tips- Modify this table to try and achieve optimum cylinder filling and to help increase volumetric efficiency. Best modified on a chassis or engine dyno so you can measure results. These are based on varying conditions and in Sport Mode.

Folder: Fuel

Basic Lambda Setpoint 1

Table Description – This is the base lambda table that the car will try and target not under full load, bank 1.

Tuning Tips – Tune this table accordingly for the target lambda values that you would like to achieve. 

Basic Lambda Setpoint 2

Table Description – This is the base lambda table that the car will try and target not under full load, bank 2.

Tuning Tips – Tune this table accordingly for the target lambda values that you would like to achieve. 

Fuel Pressure Setpoint

Table Description – This is the target fuel pressure table. 

Tuning Tips – You can increase this table if you are in need of more fuel. Data log the set point of fuel pressure with the actual fuel pressure to ensure you are within an acceptable range. 

Fuel Pressure Target for Double Injection Mode

Table Description – Fuel Pressure target for when the engine is in double or dual injection modes. Dual injection modes generally only occur during the catalytic converter warm up phase and wide open throttle from 2,600RPM to 3,000RPM. During double injection fuel is injected during both the compression and intake strokes. 

Fuel Pressure Target for Homogeneous Engine Operation

Table Description – Fuel Pressure target while the motor is in Homogeneous Engine Operation. Mostly in use during light load operation where stoichiometric AFR is desired.

High Pressure Fuel Pump Max Pressure

Table Description – This is the max fuel pressure target allowable under any condition

Tuning Tips – Likely will never need to be raised unless significant airflow changes have been made.

Lambda Full Load Enrichment

Table Description – This is target fueling for the car when in full load, or wide open throttle. These are the target value that the car will try and achieve based on an amount of time in full load. This table is used when NOT in Sport Mode.

Tuning Tips – Set these tables according to what lambda you want to run. We recommend around a .8 lambda at full load. The full load flag can be logged and serves as an indicator to when the car enters full load mode. These tables are on a timer.

Lambda Full Load Enrichment for Sport Mode

Table Description – This is target fueling for the car when in full load, or wide open throttle. These are the target value that the car will try and achieve based on an amount of time in full load. This table is used when IN Sport Mode.

Tuning Tips – Set these tables according to what lambda you want to run. We recommend around a .8 lambda at full load. The full load flag can be logged and serves as an indicator to when the car enters full load mode. There tables are on a timer.

Map for the PWM Duty Cycle of the Electrical Fuel Pump

Table Description – This table helps to control the electric fuel pump, based on fuel flow. This can be changed to help aid in fuel delivery at lower speeds.

Folder: Ignition Timing

Absolute Calibration for Reference Ignition Angle Due to Valve Overlap 0-0 thru 1-3

Table Description – These tables are ideal timing numbers to achieve overall efficiency, or MBT timing.

Tuning Tips – There should be no need to make changes to these tables, as they are theoretically ideal. If you want to make changes to ignition timing it should be done in the Calibration for Reference tables.

Calibration for Reference Ignition Angle Due to Valve Overlap 0-0 thru 1-3

Table Description – These are the main ignition timing maps. These are the maps that you will need to modify in order to make changes to the ignition timing. These are base calibration numbers for the ignition timing, before any corrections will be applied based on load.

Tuning Tips – You want to make sure that you are making changes to the all the timing maps to be sure that the car is tuned at all load sections, as it will move between the maps on varying conditions.  Essentially you will want to modify all maps equally in the same load/rpm areas.  Do not copy and paste these values.  

Folder: Knock Control

Knock Retard Threshold Per Knock Event

Table Description – The amount of timing retard in degrees that gets pulled during each knock event.

Tuning Tips – Change this if you feel that the car is pulling too much timing or too little timing depending on the knock event. USE THIS WITH GREAT CAUTION!

Knock Threshold Cylinder 1-6

Table Description – These thresholds are made to determine when the knock control system becomes active. Raising these thresholds will make the car less likely to pull timing when it hears something it deems as a knock event. Use this on built motors when the harmonics of the engine can change the amount of noise the knock sensor deems as knock, when in fact, it is just engine noise. The numbers are for each individual cylinder.

Folder: Limits

Dynamic (Increased) Engine Speed Limit for High Range

Table Description- Engine speed limiter.

Dynamic (Increased) Engine Speed Limit for Low Range

Table Description- Engine speed limiter.

Static (Standard) Engine Speed Limit for High Range

Table Description- Engine speed limiter.

Static (Standard) Engine Speed Limit for Low Range

Table Description- Engine speed limiter.

Threshold to Vehicle Speed Limitation

Table Description- Vehicle speed limiter.

Folder: Miscellaneous

Engine Displacement

Table Description- Displacement of the engine in liters.

Tuning Tips- Change this value only if the displacement of the engine changes, as this is used in the mass flow calculation by the ECU.

Folder: Sensor Calibration

Conversion Table for MAF Value

Table Description – This table is the offset to convert the raw value into the calculated value for the MAF readings.

Folder: Throttle Tables

Driver Interpretation Map for High Vehicle Speeds

Table Description- This table is a percentage of torque applied based on pedal position. This is for normal driving mode, non-sport mode. This is for high vehicle speeds which is ABOVE 70 km/h (44MPH)

Tuning Tips- Raising this table will make the pedal percentage more aggressive. It can be used to make the car feel more responsive. This table is for normal mode, NOT for Sport Mode.

Driver Interpretation Map for High Vehicle Speeds in Sport Mode

Table Description- This table is a percentage of torque applied based on pedal position. This is for sport mode. This is for high vehicle speeds which is ABOVE 70 km/h (44MPH)

Tuning Tips- Raising this table will make the pedal percentage more aggressive. It can be used to make the car feel more responsive. This table is for Sport Mode.

Driver Interpretation Map for Low Vehicle Speeds

Table Description- This table is a percentage of torque applied based on pedal position. This is for normal driving mode, non-sport mode. This is for high vehicle speeds which is BELOW 70 km/h (44MPH)

Tuning Tips- Raising this table will make the pedal percentage more aggressive. It can be used to make the car feel more responsive. This table is for normal mode, NOT for Sport Mode.

Upper Limit of the Throttle Position Setpoint

Table Description- Maximum value the throttle plate is allowed to open.

Tuning Tips- None at this time.

Precautions and Warnings – Passing 85% has been known to put cars into limp mode.

Folder: Torque Tables

Maximum Reference Indicated Engine Torque

Table Description- These tables are the maximum torque reference allowed beyond this value torque intervention will take over.

Tuning Tips- Raise these if increasing overall engine airflow.

Maximum Torque at Clutch due to Torque Limitation Depending on Gear Ratio by Auto Trans

Table Description- Maximum torque value at the clutch for a car equipped with an auto transmission.

Tuning Tips- Increase if you are hitting a torque limitation.

Maximum Torque at Clutch due to Torque Limitation Depending on Gear Ratio by Manual Trans

Table Description- Maximum torque value at the clutch for a car equipped with an auto transmission.

Tuning Tips- Increase if you are hitting a torque limitation.

Maximum Torque at Clutch due to Torque Limitation Depending on Gear Ratio by Manual Trans AWD

Table Description- Maximum torque value at the clutch for a car equipped with an auto transmission.

Tuning Tips- Increase if you are hitting a torque limitation.