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Ecu options

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Im researching into fitting a ecu to my car. Brand hasnt been chosen yet. A bit of detail of the car as this what would set the path i would go down. its a 1.0 3cylinder vag engine. Naturaly assperated at the moment. It is dbw and has variable cam timing on the inlet cam. the engine is fitted from 2013 onwards seat mii volkswagon up skoda citigo models. Polos and fabias have them aswell. Chya or chyb is the engine code.

My question is how would i go about installing a ecu. As far as i can see because its a newer car it will have its canbus issues.

As far as i can see one option would be piggyback the oem ecu. Share the cam and crank sensors and control the ignition and injectors but leave the dbw to the oem ecu. Have resistors on the output so the oem think its in control.

Option 2 is to have the oem ecu still there but have it thinking the engine isnt running.but have everything connected so there is no engine light on the dash. Standalone ecu would control abdifferent dbw setup and everything else. I need the dash to work. No lights and defentaly need the powersteering to work.

Im not sure how dumb or smart the ecu is on the car and thats why im asking this questions.

I plan on fitting a supercharger in the future which is why im wanting to go down this route but want it runing and ready to go before i do it.

I have my doubts if this has been done before but experence on newer vag cars could help


You need to learn more about the CAN bus in the vehicle. It is used for the dash gauges? Does it interact with the transmission?

I would suggest you consider an ECU that can control the DBW, variable CAM, and has flexible CAN output (depending on what you learn above). Otherwise leave the stock ECU and whatever minimal connection is required. It might just need the crank sensor and some temp sensors. You might consider replacing the gauges if that's the only thing the CAN is used for and you can't duplicate the ECU output.

Iv no idea where to start with the can bus. The car is a manual 5 speed. With a clutch switch and reverse switch. . So thats not going to be a problem. I think iv got an idea on how to get it working . Been doing more research and its a paralell setup and not piggy back im doing. is a road car so need guages to work. But powersteering is the main one. Its got a eectric steering coloum. Otherwise it would be really easy to do. The powersteering starts working once the car is running so at what point does the car think its running. When it sees a rpm signal or a alternator signal or voltage.

Im trying to cover all the potentional problems i might have

Look at the factory workshop diagram and trouble-shooting hints. Often there will be a description of what modules communicate over the CAN bus.

Can you connect with a friendly mechanic as the dealership -- what do their tools see on the CAN bus?

Does the CAN bus go to Electric Power Steering? Is the Power Steering connected through the ignition relay, so it is only on when the ignition is on?

Perhaps you should acquire some tools to capture CAN bus information and begin to decode what modules are broadcasting on the CAN bus.

My suggestion for fitting an aftermarket ECU, is get another factory wiring harness for the engine. Modify that harness to an ECU that can support the features required on your engine. You'll need that factory wiring diagram (usually found in the workshop manual) from above to help you do this. If you have any trouble with your aftermarket ECU, you can always re-connect the original harness / ECU and the car should be driveable.

To me the most difficult area with tuning modern stock ECUs is its communication with transmission which requires adjustments after modifying torque and power curves of the engine in most cases. If this car has manual transmission that makes it much easier to tune engine performance in case of supercharging - you basically just need to change your fuel and ignition settings without touching anything else. If I were you i would definitely consider the option of keeping stock ECU and reflashing it... If reflashing option is not available for your car i woukd strart looking for an aftermarket ECU options...