Running Rich after adding dual exhaust
04-05-2016, 07:50 AM
#21
I've been through this on a gbody, where I added headers and kept the feedback carb. The fuel curve leans out and the computer over compensates by pulsing the metering rods to stay out of the primary jets longer.
To head off another question that you may have about where to obtain voltage for the third wire, I hooked it up directly to the 12v distributor lead.
To head off another question that you may have about where to obtain voltage for the third wire, I hooked it up directly to the 12v distributor lead.
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htown81vette (04-05-2016)
04-05-2016, 09:17 AM
#22
Le Mans Master
your here to ask for help, so a stupid question it is not .three wire has a ground wire ,a ecm wire,and 12 volt wire.the 12 volt wire you have to wire to a power source that comes on when the key is on.gm has a three wire sensor but most go with bosch aftermarket.
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htown81vette (04-05-2016)
04-09-2016, 07:11 PM
#23
Ok, so I got my heated 02 Sensor (mail order), jacked up the car to go put it in...I am currently having trouble locating the existing 02 sensor. On my '81 it was near the drivers side exhaust manifold. No such thing exists on my 82. WEIRD. Am I looking in the wrong place? I looked on the passenger side as well.
04-10-2016, 01:57 AM
#27
I'll check on it tomorrow. I hope those knot heads didn't do that, it was never mentioned to me anyway. I would hope that if they did something like that they would let me know so I can arrange to put another 02 sensor bung in there at a later date. But if memory serves correctly they said nothing.
05-17-2016, 11:18 PM
#29
UPDATE:
After doing some checking I found that there was NO 02 SENSOR INSTALLED!!
At one point one of the previous owners may have decided it didn't need one <scratches head>. So I bought a heated 02 sensor. But I also bought a wideband.
I went to the exhaust shop and had a couple of bungs installed (no, not the Beavis and Butthead kind, lol) Then I installed the wideband to see where I was at air/fuel ratio-wise. AFR was all over the place. Super rich, super lean. At idle, the AFR was pegged at 22.5 (leanest the wideband would measure), and at WOT the AFR went pig rich at 9.9 (richest that it would measure) and everything in between. Cruising was about 13.0, but it varied wildly. You could just get a sense that the computer didn't know what the hell to do.
So then I installed the new 02 sensor. Starting off, it was much like before but you could see over time the AFR stabilizing. After about 20 minutes of driving the AFR had come down to 16's, and even saw it hit 15.9 a couple of times. At WOT was about 10.0, still to rich but the performance improved quite abit. Also noticeable was it ran smoother, had better street manners. Was just more pleasurable to drive.
After the 20 minute drive I could tell the computer was still 'learning'. It was late so I called it a day. Will do more driving and 'learning' tomorrow.
After doing some checking I found that there was NO 02 SENSOR INSTALLED!!
At one point one of the previous owners may have decided it didn't need one <scratches head>. So I bought a heated 02 sensor. But I also bought a wideband.
I went to the exhaust shop and had a couple of bungs installed (no, not the Beavis and Butthead kind, lol) Then I installed the wideband to see where I was at air/fuel ratio-wise. AFR was all over the place. Super rich, super lean. At idle, the AFR was pegged at 22.5 (leanest the wideband would measure), and at WOT the AFR went pig rich at 9.9 (richest that it would measure) and everything in between. Cruising was about 13.0, but it varied wildly. You could just get a sense that the computer didn't know what the hell to do.
So then I installed the new 02 sensor. Starting off, it was much like before but you could see over time the AFR stabilizing. After about 20 minutes of driving the AFR had come down to 16's, and even saw it hit 15.9 a couple of times. At WOT was about 10.0, still to rich but the performance improved quite abit. Also noticeable was it ran smoother, had better street manners. Was just more pleasurable to drive.
After the 20 minute drive I could tell the computer was still 'learning'. It was late so I called it a day. Will do more driving and 'learning' tomorrow.
05-18-2016, 12:08 AM
#30
Le Mans Master
It's amazing what people do and not understand the impact that it would have.
How long was it running like this? Wonder if the cylinders got washed.
I'd do a fresh oil change and see if the oil smells like fuel.
How long was it running like this? Wonder if the cylinders got washed.
I'd do a fresh oil change and see if the oil smells like fuel.
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htown81vette (05-18-2016)
05-18-2016, 12:37 AM
#31
I'm gonna check the plugs tomorrow. I'm not sure how long it's been running that way. I hope the damage is minimal.
