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Stratified E30 Tuning – rev 4

Stratified Automotive Controls Logo
Stratified Automotive Controls

The fourth revision of the Stratified E30 tune for my IS38 equipped GTI is producing the following results compared to the third revision. (rev 4 are the dashed lines and rev 3 are the solid lines)

Boost pressure is slightly higher at boost onset and is no longer dipping around 5,000 RPM.

Stratified 1.3 vs 1.4 Boost Pressure
1.3 vs 1.4 Boost Pressure

AFR is staying consistent with this revision.

Stratified 1.3 vs 1.4 AFR
1.3 vs 1.4 AFR

Wheelspin is continuing to have an adverse affect on the ignition timing, though once things steady up around 5,300 RPM ( ~70 MPH) there is roughly one more degree of advance.

Stratified 1.3 vs 1.4 Ignition Timing
1.3 vs 1.4 Ignition Timing

Intake air temperature for these pulls was around the same as it was with revision three, catching a break with logging on days with similar ambient temperature conditions.

Stratified 1.3 vs 1.4 IAT
1.3 vs 1.4 IAT

As with revision three the Low Pressure Fuel Line pressure drops as the pull progresses.

Low Pressure Fuel Supply Pressure

With this revision the LPFP is being pushed sooner and with a couple of percent higher duty cycle.

Stratified 1.3 vs 1.4 LPFP Duty Cycle
1.3 vs 1.4 LPFP Duty Cycle

Acceleration time remains approximately the same as with revision three and still a bit longer than with some of the earlier revisions. Data points 20, 21, and 22 are revision 4.

Stratified 1.4 Acceleration Times
1.4 Acceleration Times

Revisiting the potential cause of the slower acceleration times as the tune continues to be refined, the chart below shows the vehicle speed reported by the ECU. The area highlighted inside the yellow circle shows the speed jumping around, indicative of the wheels having a momentary slip condition.

Stratified 1.4 MPH
1.4 MPH

This illustration along with the chart of Ignition Timing shows that from soon after boost leveling off around 3400 RPM up until about 5300 RPM the car is having traction issues. With that much time spent not getting good grip with the road it’s not surprising that the acceleration time is growing longer.