Any questions you have before you begin buying, building and installing.
By G4FA
#37128
Im planning on doing a piggyback install so i could easily return to stock whenever needed, however im not very sure about how to wire everything.

The engine is G4FA hyundai, with electronic throttle, COP, & hall crank.

For crank i plan on welding in a new missing tooth wheel on the crank pulley and a new hall sensor so no sharing.

My trouble is, can i share the IAT, CLT, tps(if i figure out the pins) and NB o2 sensor?
Do i wire them in parallel to the stock ecu? Or do i just wire in the signal wires?

So for example, with IAT do i just wire the negative wire the stock ecu?
Do i just wire the signal wire of the tps?

Or do i connect all wires +- and signal?
User avatar
By PSIG
#37136
G4FA wrote: Thu Aug 15, 2019 7:23 am My trouble is, can i share the IAT, CLT, tps(if i figure out the pins) and NB o2 sensor?
Welcome. Yes, if you understand how and why this could work, you could share the signals with Speeduino if the OEM sensor voltage power is 5V. ImageDo not attempt to share signals if you do not understand, in order to share safely. Share only the signals. IAT and CLT require removing the Speeduino bias resistors, setting the calibration bias to match the OEM bias, and share exact Speeduino main power and ground points with the OEM ECM in order to avoid voltage offsets.

Similarly with TPS, only share signal to Speeduino using the OEM ECM to power the sensor. ImageTest each signal wire output in order to verify expected voltages before connecting to Speeduino, in order to avoid damage to either ECM. In each case, the goal is to allow Speeduino to only "listen" to the OEM ECM's signals without powering or affecting the sensors or their signals.

Speeduino will not share its outputs. The OEM ECM should be disconnected from those devices. Note this may throw codes in the OEM ECM if it expects feedback from those devices. The OEM ECM will also throw codes if operation is not as-expected during certain functions, e.g., EGR. Likewise, results from Speeduino may be affected if those other functions remain active or controlled by the OEM ECM, as for example Speeduino will not know EGR is being added or how to deal with it.

ImageLegality and safety of any changes you make are your responsibility as control will affect or eliminate some functions (e.g., emissions), safety may be affected (e.g., traction control), and there is potential for damage to some components (e.g., catalytic converters) without proper control of outputs.

David
By G4FA
#37140
Hi David, thanks for the detailed answers, i somehow understand it a little better. Im not exactly sure how to proceed with trying to understand how the stock ecu works and at what voltage things happen. I think i might just try to add new sensors instead of sharing with existing ones.

I was planning on trying to hookup sensors first and run the car a few days to see if speeduino can read the sensors correctly, then proceed with wiring up the injectors(batch) while stock ecu still controls the ignition. I believe this is megasquirt recomended install process for beginners.

Bert
User avatar
By SaadChaara
#54836
G4FA wrote:Hi David, thanks for the detailed answers, i somehow understand it a little better. Im not exactly sure how to proceed with trying to understand how the stock ecu works and at what voltage things happen. I think i might just try to add new sensors instead of sharing with existing ones.

I was planning on trying to hookup sensors first and run the car a few days to see if speeduino can read the sensors correctly, then proceed with wiring up the injectors(batch) while stock ecu still controls the ignition. I believe this is megasquirt recomended install process for beginners.

Bert
Hello G4FA

Im planning to go as you was planning and i wish if you can give us the update of your project and if you continued with it or not

Thank you

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