throttle body

[Psychopete]

Interesting about the MAP sensor. I didn't really notice any change when I unhooked it, but came to mind since I thought your elevation might contribute to the 41 code if it couldn't determine the right altitude. Who knows.

Check out section 6.1 in the MAF conversion article (http://www.therangerstation.com/tech_library/MAF_Conversion.html), the author suggests leave it open to the atmosphere and leave it hooked up electrically. But "don't ask him why." This is why I did it that way in the first place. On fordfuelinjection.com (http://www.fordfuelinjection.com/?p=27) it states the map sensor "affects air/fuel ratio, ignition timing, EGR flow and altitude compensation."

My 88' was almost a plug in play swap, I think the author was just pointing out that that's how the original o2 4-wire circuit worked compared to the 3. He stated he didn't notice any difference with it jumpered. I did some research and found that the 4th wire is typically a dedicated ground - 2 being for the heating element, one being the signal, and the other just being a ground.

I think just as long as your exhaust is getting grounded well, you can leave it alone. I think it's basically there to insure that the o2 is always getting a good ground.

I am getting kind of mislead on the way the circuit works between the article, fordfuelinjection.com, and a generic Hayes diagram. What it looks like is jumpering pin #46 to #49 could potentially be a bad idea. It looks like pin #46 is what the sensor is sending back to the PCM, if #49 is a ground for the 4 wire sensor, it seems like that is going to screw up the readings from the oxygen sensor if #46 is it's signal return.

Pete

 

[holyford86]

well I went through and connected the HEGO ground to the signal return, I figured that the signal return is used as the HEGO ground in the 90 setup, so I chopped it at the computer and just ran it into the sig return and just left the ground wire in the harness flopping in the breeze. I scanned it today at work with the modis and got all pass codes so far, even the 41 disappeared, but I only drove it about 15 miles after moving the wire around, I'll drive it for a week and see what I get. I might just find the other end of the HEGO ground wire that I cut and reroute it to the O2 sensor so its there and if I ever replace the sensor I will add the pin and run it according to the 90 diagram. I have to add the other two wires for the diagnostic connector one of these days too.