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Tricking a stock ECU

 
Old 11-16-2016, 08:39 PM
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Default Tricking a stock ECU

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Hey guys I've lurked on this forum for a while but finally need help with something and couldn't find the answer after much tedious searching and asking fellow miata owners, so I made an account and an intro post in the meet and great forum. The issue I need help with is, at its simplest, tricking the stock ecu. Here's what I've got going:

I installed an Innovate MTX-L wideband in my car as the first step towards my turbo build. I am still running the stock ecu and replaced the stock pre-cat o2 sensor with the wideband. By hooking up the narrowband output from the Innovate gauge to the factory harness so that the stock ecu gets a signal it can work with. The issue I am experiencing is that the heater circuit for the wideband sensor is controlled through the gauge while the factory o2 heater circuit runs from the harness. This causes the ecu to think that the heater circuit is not working properly. I have since tried splicing in a 6 ohm resistor and a condenser to try and mimic the heater but to no avail. All to say does anyone know of a way to trick the stock ecu into thinking the o2 sensor heater is still in the circuit and working? any help appreciated!
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Old 11-16-2016, 08:48 PM
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Simplest way is to have an exhaust shop weld in a second bung for you, and run the stock narrowband. Then no trickery is involved.
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Old 11-16-2016, 09:01 PM
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Originally Posted by Mobius View Post
Simplest way is to have an exhaust shop weld in a second bung for you, and run the stock narrowband. Then no trickery is involved.
Thanks for the input, im hoping theres a way to do this without having to add a bung but there may not be. If thats the case though ill probably just leave it as is until i get megasquirt.
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Old 11-16-2016, 09:25 PM
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Additional bung cost me 20 minutes and 20 bucks at our local shop. He put a plug in it until I could put the car up and thread in the sensor.
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Old 11-16-2016, 09:44 PM
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Originally Posted by DNMakinson View Post
Additional bung cost me 20 minutes and 20 bucks at our local shop. He put a plug in it until I could put the car up and thread in the sensor.
I mean I have a bung and a welder but ive already done wiring etc and since its only a few months till i get my megasquirt id rather drive it with the engine light on till then than to undo all the stuff ive already done.
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Old 11-17-2016, 12:00 AM
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Just put a resistor (high wattage) in the heater circuit. I believe I'm using 10Ohms. Word of warning: 10 Ohms and 14V means 20W power dissipation.
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Old 11-17-2016, 12:42 PM
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Forget a bung if it is temporary. Drill and tap the pipe and screw the stock o2 into it. Short term solution.
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