Drift Tengoku — September 2004 · Page 82

An ignition map reveals a car's specification! Remember air fuel ratio and ignition timing? If not, reread lesson 4 in July and lesson 5 in August. Map 1 is Mikami of 3UP's ignition map for a PS13 with an S15 turbo; map 2 is the stock PS13 map. The ignition...

Lesson 5: differences between tuning data

Previous lessons explained what ECU tuning actually does. Having covered the broad principles over five lessons, we will now examine a finished ECU calibration and explain what it represents.

When requesting tuning from a shop...

...prepare properly. After six months of explanations, you should have some idea what ECU tuning involves and fewer concerns about asking a shop. At minimum, fill the fuel tank and check tire tread. If you know of a fault, repair it beforehand or ask the shop...

...you may not notice every fault. Asking the shop to handle repairs and tuning together is fine, but a car full of problems cannot receive satisfactory tuning if you insist on tuning alone. If necessary repairs are then disputed and unpaid, the tuner loses motivation. Tell us when it runs poorly: we are professionals and can deal with it.

H

...to repair it while tuning. Many people overlook this. I drive the cars myself: I cannot use full throttle with tires about to burst. Fill the tank and remove rubbish from the cabin; this is not a fuel station! Some faults may be hard to identify yourself...

Effects of advancing ignition timing: high rpm and high load; naturally aspirated region and initial boost

School

Reduces the drop in performance as boost falls; improves response when accelerating from low rpm

4. Ignition timing outside boost

The highlighted region directly affects response when opening the throttle. Circuit driving at high rpm may use it less, but street drivers can strongly feel the difference.

Under full throttle

With an S15 turbo, boost starts falling above 6,000 rpm. Slightly advancing timing here can extend high rpm pull, but knock becomes more likely, so experience and careful testing matter.

3. High rpm ignition timing

Movement of the map's reading point

Opening the throttle

...timing is generally more advanced, represented by larger numbers. The rev limit is raised to 7,800 rpm and maximum boost to 1.15. The map shows ignition timing at a given rpm and engine load. RPM is on the vertical axis, load on the horizontal. For example, around 3,000 rpm and load...

During partial throttle driving

5

2. Stock PS13 ignition map

...of 0.07, around the start of boost, timing is 37° before top dead center. [Some source figures are poorly recognized.]

...that's how to read it.

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