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07 focus, downstream??
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bdancik Offline
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Post: #1
07 focus, downstream??
I acquired a wiring diagram on my 07 ford focus, and it appears as if the downstream o2 sensors contols the air fuel ratio, is this possible??

Brian
07-03-2008 08:22 PM
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mike Offline
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RE: 07 focus, downstream??
Let's be clear on the definition of "downstream sensor". Do you mean downstream from the catalytic converter? If so, then no, there's no way.

I have seen a setup where there were 2 sensors upstream of the cat, and the downstream of those two sensors was used by the ECU for AFR calcs. But it was still upstream from the cat.

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07-04-2008 08:08 AM
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colchiro Offline
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RE: 07 focus, downstream??
The sensors closest to the engine (between the cat and engine) determine the mix.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-04-2008 09:28 AM
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tooler1988 Offline
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RE: 07 focus, downstream??
colchiro Wrote:The sensors closest to the engine (between the cat and engine) determine the mix.
What happens in the case of having two Cat's? I am assuming That the sensor before the first and befort the second are what I need to work with? Is that correct?

Thanks
Tooler
07-04-2008 09:30 AM
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colchiro Offline
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RE: 07 focus, downstream??
Yes, you'd need a double EFIE (or two single EFIE's) then, (assuming you have an o2 sensor and not an air-fuel sensor or wide band sensor, which may not be compatible).

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-04-2008 10:43 AM
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maxc Offline
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Post: #6
RE: 07 focus, downstream??
Hi all, I have listen too all of the HAFC hot lines. From 2004 and up alot of the computars are looking at the rear 02's to adjust fuel trims. There putting 4 ohm resisters on the ground signal wires on some. http://installersupport.info/teleconference.htm
07-04-2008 03:42 PM
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bdancik Offline
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RE: 07 focus, downstream??
If someone has a fax, i'd gladly send the docs I have to you. I'd be more then happy to get a second opinion.
07-04-2008 07:03 PM
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nismotekk Offline
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RE: 07 focus, downstream??
bdancik Wrote:If someone has a fax, i'd gladly send the docs I have to you. I'd be more then happy to get a second opinion.

I dont believe the rear o2 is controlling the A/F ratio, but it is entirely possible that the ECU is collecting the data from the rear o2 and making minute emission adjustments. I have seen it, nissan does it. Your ECU still uses the front sensor, be it o2 or AFR to calculate A/F ratio. I will see if I can pull up alldata on my home computer and get back with you.
07-06-2008 01:02 PM
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