A better grounding solution (earth mod)
07 August 2004, 10:17 PM
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A better grounding solution (earth mod)
Among the different Scooby sensors, the MAF and the rear O2 sensors are the more prone to ground or signal perturbations because a small amount of voltage creates a big difference in results. The O2 sensor, used during idle and closed-loop phases is definitively the more sensible as its transfer function around the stochïo point looks like a filtered step. Hundreds of millivolts are enough to change the reading from 12:1 to 16:1 !
I've measured hundredths of ohms between the rear O2 sensor's ground and ECU's ground, enough to create hundreds millivolts noise when ignition coils are fired !
The mod simply consists to connect the rear O2 sensor's ground wire to the ECU ground using normal small electronic wire. For example, on a 01-04WRX/STi, you just have to connect B134 pin 22 to B135 pin 19. Results are even better on a MY95-00 scooby.
I've measured hundredths of ohms between the rear O2 sensor's ground and ECU's ground, enough to create hundreds millivolts noise when ignition coils are fired !
The mod simply consists to connect the rear O2 sensor's ground wire to the ECU ground using normal small electronic wire. For example, on a 01-04WRX/STi, you just have to connect B134 pin 22 to B135 pin 19. Results are even better on a MY95-00 scooby.
Last edited by XNWRX; 09 August 2004 at 11:30 AM.
07 August 2004, 10:42 PM
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Originally Posted by XNWRX
Among the different Scooby sensors, the MAF and the rear O2 sensors are the more prone to ground or signal perturbations because a small amount of voltage creates a big difference in results. The O2 sensor, used during idle and closed-loop phases is definitively the more sensible as its transfer function around the stochïo point looks like a filtered step. Hundreds of millivolts are enough to change the reading from 12:1 to 16:1 !
I've measured hundredths of ohms between the rear O2 sensor's ground and ECU's ground, enough to create hundreds millivolts noise when ignition coils are fired !
The mod simply consists to connect the rear O2 sensor's ground wire to the ECU ground using normal small electronic wire. For example, on a 01-04WRX/STi, you just have to connect B134 pin 17 to pin 19. Results are even better on a MY95-00 scooby.
I've measured hundredths of ohms between the rear O2 sensor's ground and ECU's ground, enough to create hundreds millivolts noise when ignition coils are fired !
The mod simply consists to connect the rear O2 sensor's ground wire to the ECU ground using normal small electronic wire. For example, on a 01-04WRX/STi, you just have to connect B134 pin 17 to pin 19. Results are even better on a MY95-00 scooby.
Thoughts??!
Cheers,
Andy
11 August 2004, 08:14 AM
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Sorry, I've been trying to find this ground O2 sensor signal on MY95-00 scoob, but it's not fitted to the ECU as opposed to 00-04WRX/STi. It seems that it is connected straight from the O2 sensor to the engine's body (good reason for the problem). I haven't been able to locate it.
Then the only mod consists in cabling that engine point to the battery ground, a big wire is not needed.
Then the only mod consists in cabling that engine point to the battery ground, a big wire is not needed.
12 August 2004, 10:26 PM
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I thought it was the front O2 sensor on the Newage cars that was "used during idle and closed-loop phases" and the rear O2 just monitored the CAT(s)
efficiency.
Am I mistaken?
Mark.
efficiency.
Am I mistaken?
Mark.
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