Rumor about convertibl ecu???
 

rumor has it that the convertible ecu can be used on turbo motors. i have heard this from a few places and people. just wondering if anyone else has heard this, or can confirm or deny this as true.

The N338 ECU found on the 88 convertible can be used in repalcement of any N33X ECU (such as the N332 and N333 found on the US spec S4 Turbo models)

ok so its just s4 not s5?

The first 3 digits reference the Harness and engine the ECU can be used with. For you to use another ECU the first 3 digits must match or the engine harness must be changed.

For example a N338 ECU could be used on any N33X series engine/harness combination like a N333 or N332.

But it could not be used on a car with a N370 harness ECU as the S5 Turbos use.

See only the first two digits match, not the third one with references the harness.

So no, you couldn't use any S4 ECU on a S5 car or S5 engine/harness combination.

and that's why...
 

So if I understand you correctly, IceMark, that's why it is possible to use a NA ECU/harness with a swapped TII with some wiring mods since you are essentially upgrading the harness to TII-grade. Ah, it's all becoming clear...

Personally I don't see how a ECU that was meant for a non turbo car could be used on a turbo.

The output of the pressure/boost sensors are not even close to each other.

I'm talking the output TO the ECU from the boost/pressure sensors. The ECU on a na is looking for a set of values that won't be there if a tubo boost/pressue sensor is used.

dont question law.

the only possible reasoning behind this is that Mazda decided at the last minute not to make the verts turbo and forgot to remove the ecu?

FWIW, when I originally swapped the turbo into my 'vert, i tried to use the vert ecu (1988, N338), and it idled well enough and drove ok at low RPM/low load... but the first time i built up any substantial boost (only about 4 psi)... pop! There goes an apex seal. After it was rebuilt, I went with a megasquirt, cause at least that way i have some control over what the engines doing, and the MS1 was only $200 (plus maybe $50 in other chips, wiring supplies etc)

I tend to agree. Although I used a vert ECU and Turbo AFM and Turbo Pressure sensor, and Turbo knock box on a Turbo motor set up for about 6 months without any problems, I don't think that it is the optimal way to do it.

The S4 Turbo and Non turbo engine harnesses are nearly the same, with only minor wiring differences. But differences that do require some wiring changes.