Tests

          1. The values shown are degrees advance BTDC as a function of loads & RPMs.
          2. The data set for each chip is a 12 X 12 matrix plus a WOT vector. The selective
              data above indicate where variations exist in the matrices and vectors from the
              stock chip. The data points not shown were basically the same as the stock values.
              The data were determined by using an EPROM editor on a PC which provides
              actual timing advances & fuel enrichments from their respective maps.
          3. The results indicate that all the performance chips kept the fuel maps essentially
              unchanged from the stock '88/'89 911 Carrera. Fuel map changes have little to
              no effect, with the exception of the WOT map, when operating closed-loop via
              the O2 sensor.
          4. The key similarity between all the performance chips is the "pushed" ignition
              timing maps. The timing maps of these chips have advanced the timing as much
              as 10 degrees over the stock maps to a value of 50 degrees advance BTDC.
              This 50 degree advance value exceeds by more than 10 degrees what Porsche
              techs consider the maximum advance for a 911 engine, irrespective of octane
              levels and fuels available, with a single plug ignition system. Porsche with its Club
              Sport DME did not even "push" the timing maps, but used the stock '88/'89 maps.
              Additionally, all performance chips increased the rev limit; A - 6920, B - 6840,
              C - 7040, versus the stock chip set to 6520 and the Club Sport set to 6840.
          5. The results indicate that pinging/detonation will occur with performance chips,
              whether audible or sub-audible, because of the excessive timing advances used
              which become more problematic with increasing temperatures & heavy engine loads.
              Furthermore, because of the single spark plug and its location, the early air cooled
              911 engine is more prone to detonation the result of non-stock ignition advances,
              versus a center located spark plug of the later water cooled 911, resulting in long
              term possible engine damage. Also, emission tests may fail NOx because of
              excessive timing advances under certain engine loads/RPMs in addition to idling
              problems, i.e. surging or a high idle.
          6. The overall results are basically analogous with the re-adjustment of the distributor,
              on engines without an engine management system, to advance the ignition timing
              beyond the stock specification for performance effects, i.e. a more responsive
              feeling engine.

AFM Voltage Output Comparison

Flap Angle (degrees)	Analog ECM (volts)	Digital ECM (volts)
0	1.70	.25
15	3.20	.55
30	5.00	1.05
60	6.80	2.30
90	7.36	3.45
110	7.58	4.50

Notes:

          1. The maximum flap angle is 110 degrees.
          2. The analog ECM is L-Jetronic & the digital ECM is Motronic.
          3. The input voltages are; analog ECM AFM = 12.0 volts, digital ECM AFM = 5.00 volts.
          4. V(out) analog ECM AFM = F (sqrt flap angle), V(out) digital ECM AFM = F (flap angle)

MAP Sensor Fuel Injection Pulse Comparison

Manifold Vacuum (psi)	Digital ECM (ms)	Analog ECM (ms)
0	3.75	7.0/4.5
5	3.30	5.8/4.0
10	2.85	4.2'3.0
15	2.40	3.0/2.3
20	1.95	2.3/1.7
25	1.50	1.7/1.4

Notes:

          1. The times shown are the injector pulse widths at normal operating temperatures.
          2. The analog ECM times are for a D-Jetronic ECM at low/high RPMs.
          3. The injection time T = T(min) + (T(max) - T(min)) X (1 - MAP / MAP(max)),
              where MAP is the manifold vacuum & MAP(max) is the maximum manifold vacuum.
          4. A manifold vacuum of 14.5 psi = 100 kPA = 1 Bar.

Porsche 993 MAF & DME System Data

RPM	MAF (volts)	Mass Flow	Ignition Timing	Load (ms)	Pulse (ms)
Idle	.80	27	3.5	1.80	3.3
1000	.90	30	13	1.40	2.9
2000	1.05	45	32	1.20	2.3
3000	1.25	64	35	1.10	2.3
4000	1.40	91	38	1.20	2.3

Notes:

          1. The Mass Flow values are shown in kilograms per hour (kg/h).
          2. The MAF sensor is a hot film type mass air flow sensor.
          3. The Pulse values are the injection pulse width times.
          4. The engine conditions were; fully warm, unloaded, & Lambda = 1.0.
          5. The ignition timing is in degrees advance BTDC.
          6. The data were determined using the Porsche PST2.

Porsche 986/996 MAF & DME System Data

RPM	MAF (volts)	Mass Flow	Ignition Timing	Load (ms)	Pulse (ms)
Idle	1.30	15	5.0	1.10	2.6
1000	1.35	20	10	1.20	2.6
2000	1.70	40	23	1.20	2.7
3000	1.90	60	32	1.20	2.7
4000	2.11	80	36	1.20	2.6

Notes:

          1. The Mass Flow values are shown in kilograms per hour (kg/h).
          2. The MAF sensor is a hot film type mass air flow sensor.
          3. The Pulse values are the injection pulse width times.
          4. The engine conditions were; fully warm, unloaded, & Lambda = 1.0.
          5. The ignition timing is in degrees advance BTDC, with a maximum of less than 40 degrees.
          6. The data were determined using the Porsche PST2.