1994 Porsche 911 Carrera 2 (993)

UPDATE 28.05.13

Car has been converted to ITB's and Alpha-N, running OK, some tuning is still needed though.


UPDATE 23.06.2008: Car is running for two months now very well. I fabricated an intercooler, installed Siemens 630cc injectors and Bosch direct ignition. Made 440 hp/650 Nm on the dyno.

Here's some pics:




Nice !

Can you post configs ? (mcd / mct) thanx.

Sorry, I only have .msq file right now handy. It's for 1.0.73 (16x14 tables), packed with WinRAR?:

It has air-cooled flat-six 3.6litre engine (CR= 11.3 : 1) and it has supercharger installed. Originally 272 hp, SC should add around 130 hp. Isn't CR=11.3 a bit high for supercharging ? What fuel will you use ?

ECU has Motronic 55pin connector and since the car has very low mileage (109 000 kms) and wires are in excellent condition, I'd like to install PnP? VEMS.

Car has twin-plug cylinder heads (total of 12 plugs) and two distributors. Plan is to eliminate these and use two Bosch 2x3 coil-packs. Firing order: 1-6-2-4-3-5

I'm aware of the wasted spark configuration in twin plug system:

Note that we left out ignch4 and ignch5 that are logiclevel in the default 6+2 ignition output setup.

UPDATE on PnP? ECU: PnP? is possible and using stock twin-distributor igntion which requires logic-level outputs from VEMS (either IGN or stepper). All other sensors are VEMS-compatible.

If the car has ABD (Automatic Brake Differential, sort of traction control), using VEMS means that ABD warning light will be burning. ABD brain needs TPS signal but at the moment I don't know if it's usual analog signal or digital. This is not a priority also for us.

Also flyback wire must be connected, but I used separate wire in the loom which I made for Wbo2, ignition etc.

Here's ECU pinout for that car: Porsche%20993%20Carrera2.JPG

Primary trigger is VR, 60-2 standard type.

Measure sensor resistance (likely 400..1200 Ohm)

Can you check polarity ?

Maybe measure with scope (or soundcard, but than soundcard polarity also needs to be checked) ?

Scope is best because amplitude can also be seen (for a given RPM).

If the sensor can be reached , than a simply DVM will reveal the sensor polarity

If the polarity is reverse, the 2 wires of the sensor must be reversed (what was ground will become VR signal). If the VR sensor ground is only connected to an ECU pin (not connected to the ground of any other sensor), than there is nothing to do.

Secondary trigger is HALL sensor in the distributor. Since wasted spark, not needed.

CLT is NTC type

IAT is NTC type

Injectors will be most likely 500-600cc (have to be changed, stock ones are too small) High-Z together with transient 30V diode.

IAC valve is PWM type, 3 wires.

TPS is variable.

Under ivenstigation:

I can add additional information about the car if needed, right now I don't now what to add more.

Can you write the pins as text ?

Pin noDescriptionVEMS pin
1Resonance flap 
2Variant coding unused
3MFI+ DI Relayterm 85b 
4TRP-OPEN3wire IAC valve open
6TN Signal ????
7Primary trigger VR signal 
8Sec. trigger HALL signal 
9Vehicle speed sensor 
10Oxygen sensor GND 
11Knock sensor 1 
12+5 Volt supply EC36pin28 ECU 5V output
13Diagnosis "L" 
14Sensor GND 
15Unknown N/C 
17INJECTOR CYL1, TI Signal (?) 
19Electronics GND 
20Oxygen sensor Heater 
21Malfunction indicator lamp 
22TRP-CLOSE3wire IAC valve close
25ACTUATION IC1Logic-level ignition output for distributor 1
26RPM Signal Ground 
27TERM 15 
28Oxygen Sensor Signal 
29Knock sensor2 
30Knock sensor GND 
31Actuation IC2Logic-level ignition output for distributor 2
32Secondary air pump relay 
33Valve tank venting 
36MFI + DI Relayterm 85 
37MFI+Relayterm 87 
38Unknown (N/C?) 
39Unknown (N/C?) 
40Compressor switch input or output? current ?
41Vacuum coasting shutoff input or output ?
42Stepped switch ????
43Unknown (NC?) 
44MAP Coding 
45Engine temperature 
46Unknown (NC?) 
47Intake Air Temperature 
48SS Connection B VR sensor -
49SS Connection A VR sensor +
50Signal Knocking Yes/no 
51Transmission input not used
52PWM for what????
53TVS Throttle position sensor
54Variant Coding unused
55 Diagnosis "K" unused

Pins marked as "unknown NC" are the ones that were not on the pinout. I have to veryfy on the car that they're nonexistant. Or they might exist, just be unimportant.

Is there an analog TPS signal ? which pin ?

Not that the car does not have cruise control and is manual not automatic (so transmission input might not be used in this model... or the factory ECU might sense neutral ... not very important).

Can you unplug motronics, and do some ohm measurements as verification ?

Sensors like CLT, MAT, VRtrigger (take note of which ground signal you measured against).

We'll have to make a "Porsche" column in the spreadsheet in

If we can do that, the PNP VEMS should be possible. The few extra wires for the WBO2 (and maybe shiftlight and launch input) should be easy through endplate.