Wiring and connector to the oxygen sensor
04-06-2005, 02:19 PM
#1
Burning Brakes
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Wiring and connector to the oxygen sensor
I need to install the oxygen sensor on my (early) 944. I already bought a universal single-wire sensor. The sensor comes with a very short wire. I could splice it to the existing wire, but:
the connector (on top/behind of the engine) is partially broken, and I'm not sure if it contacts well. I'd like to remove this connector, and replace the wire to the oxygen sensor with a new one.
I need some hints here, e.g.
the (green) sensor wire that goes to the DME is a shielded wire. Is the wire from the sensor to the connector (mentioned above) also shielded?
Do I need to use teflon coates wire, etc, or regular wire insulation would melt near the exhaust?
Any suggestions for off-the-shelf replacements for this connector, or I just should solder it permanently? I know there needs to be an opening for air to get to the sensor somehow through the wires, but air could get there where I splice the wire form the sensor (15cm from the sensor).
Also, for the same reason, I think it wouldn't be good to put heat shrink around that splicing. On the other hand, dirt will get there eventually, so what do I do?
the connector (on top/behind of the engine) is partially broken, and I'm not sure if it contacts well. I'd like to remove this connector, and replace the wire to the oxygen sensor with a new one.
I need some hints here, e.g.
the (green) sensor wire that goes to the DME is a shielded wire. Is the wire from the sensor to the connector (mentioned above) also shielded?
Do I need to use teflon coates wire, etc, or regular wire insulation would melt near the exhaust?
Any suggestions for off-the-shelf replacements for this connector, or I just should solder it permanently? I know there needs to be an opening for air to get to the sensor somehow through the wires, but air could get there where I splice the wire form the sensor (15cm from the sensor).
Also, for the same reason, I think it wouldn't be good to put heat shrink around that splicing. On the other hand, dirt will get there eventually, so what do I do?
04-06-2005, 03:23 PM
#2
Three Wheelin'
Had the same problem with my '84. I just cut the busted connector off and used spade style crimp on connectors. The best connectors are the ones with plastic covers. Don't worry about the braided shield, just put some heat shrink over it.
When you splice in the new nensor, use a crimp on butt splice. You do not want to solder the O2 sensor lead because the sensor gets its reference atomsphere through the gaps between the insulation and the wire strands. If you solder the splice you seal the insulation to the wire and the sensor is useless.
When you splice in the new nensor, use a crimp on butt splice. You do not want to solder the O2 sensor lead because the sensor gets its reference atomsphere through the gaps between the insulation and the wire strands. If you solder the splice you seal the insulation to the wire and the sensor is useless.
04-06-2005, 06:24 PM
#3
Burning Brakes
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Originally Posted by Charlotte944
Don't worry about the braided shield, just put some heat shrink over it.
Another question: is it OK to put antisieze on the threads, or that would interfere/damage the sensor?
04-06-2005, 07:23 PM
#4
Race Car
Funny, I just had this conversation w/someone last night. His comments were:
1. That wire is a specific length for a reason. There is a very low ohm reading that goes to the DME. If the wire is too long it will change that reading due to resistance lost or gained caused by the longer/shorter wire. It will be slight however it is already low. Not much room for variation.
2. Cut back the outer wire housing and strip it back far enough to expose the shielding. Pull back the shielding and cut the interior wire and cover. Cut back that wires cover enough to solder the replacement to the harness side.
3. Do the same thing with the harness side wiring. Wrap the newly soldered connection and use something like electrical tape to cover the exposed center wire, or you could use a very small butt connector with a VERY thin plastic cover.
4. Pull the outer sheilding wire back over the new connection making sure that you have good contact or overlap between the terminal end and the harness end of the wire.
5 Now shrink wrap over the entire connection.
Just make sure that the wire ends up as close to the original length as possible when you are finished. Take your time and plan out what you are doing before you make any cuts. Not much room for error "IF" you want the O2 sensor to do what it is supposed to do.
I am sure that he will correct some portion of this later BUT I think that I have described it pretty well.
Good luck,
Michael
1. That wire is a specific length for a reason. There is a very low ohm reading that goes to the DME. If the wire is too long it will change that reading due to resistance lost or gained caused by the longer/shorter wire. It will be slight however it is already low. Not much room for variation.
2. Cut back the outer wire housing and strip it back far enough to expose the shielding. Pull back the shielding and cut the interior wire and cover. Cut back that wires cover enough to solder the replacement to the harness side.
3. Do the same thing with the harness side wiring. Wrap the newly soldered connection and use something like electrical tape to cover the exposed center wire, or you could use a very small butt connector with a VERY thin plastic cover.
4. Pull the outer sheilding wire back over the new connection making sure that you have good contact or overlap between the terminal end and the harness end of the wire.
5 Now shrink wrap over the entire connection.
Just make sure that the wire ends up as close to the original length as possible when you are finished. Take your time and plan out what you are doing before you make any cuts. Not much room for error "IF" you want the O2 sensor to do what it is supposed to do.
I am sure that he will correct some portion of this later BUT I think that I have described it pretty well.
Good luck,
Michael
