CARBURETION and your Large/Small port 16V 4AG

[firehawk]

BenR Wrote:You can still use the Stock ECU to control timing if you continue to provide it with a semi stable map and TPS signal, its not redundant.

For now, I'm planning to use the stock ECU/distributor for ignition on my car with 44 PHH Mikunis and have been studying how it all works. I've read Jeremy's excellent pages (see here) several times over and asked a bit of advice from him as well. Apparently TPS voltage signal is not needed used for ignition at all and the basic advance map uses RPM and MAP for choosing the advance angle. The IDL signal from the TPS is used to select a simple advance map used for idle/engine braking. If IDL is left open, the ECU will always use the basic map. The intake air temp sensor (THA) will also be missing, but the sensor can be replaced with a 2kohm resistor to make the ECU see a constant 20 celcius temperature.

However, as a longer-term solution, I'm planning on making a simple mappable ignition-only system which replaces the microcontroller inside the standard ECU and uses the standard distributor, igniter/coil and remaining sensors. It'll be a long-term project so don't expect any results yet but hopefully I'll have something to test on my car in the autumn.