spearson

The wire harness for the 02 sensor and the temp sensor has been lying a little too close to the exhaust manifold. So close in fact that the plastic protective tubing has a good 5 inch chunk melted completely away, and the wire coating on each wire has also been completely melted away. These wires have been exposed and in contact with the exhaust manifold for who knows how long, there are two marks on the manifold where they have been in contact.

I have a spare 02 sensor and was going to go out and replace the current one after reading a post about how a bad 02 could cause a lean condition and thus detonation. I was trying to get a good view of the 02 sensor to see how easy it was to get at when I noticed what looked like melted wires, and upon further inspection turned out to be exposed corroded and partially broken wires.

It really makes sense now why I have detonation, why I have a code 44, and why my electric fan doesn't turn on.

So my question is, is it safe to splice in new wire or should I replace the whole harness?

I assume a exposed wire and the exhaust manifold cause some short circuit, could this be damaging at all to the ecm?

8Mike9

No damage to the ECM as I see it. Should be okay to splice as well...used to be you could get an "universal O2" sensor, and cut and connect without ill effect, I don't see why it'd be an different now.

thunderstick

neither the O2 or the temp sender have anything to do with your fan not coming on. you have other problems there... fan switch is on the passenger head between #6 and #8. i'd look there... if your temp wire was grounded out, your gauge would peg out, or read nothing if it was burnt all the way through.

spearson

I don't remember exactly, but we had a schematic for the fan switch circuit. And there were three sensors it used in the circuit. And that drivers side head temp sensor was part of it I thought.

But in any case, my temp gauge has been acting wierd, it bounces all over the place, so there are problems with that wire.

8Mike9

If you have TPI you have 3 sensors...one for the gauge (between and under #1 and #3 sparkplugs.

The CTS in front of the intake manifold...ECM uses this for Temp refernce and as well as when to turn on the primary fan,

And then between and under #6 and #8 sparkplugs is the secondary fan switch.

The one for e gauge won't cause any drivability issues, nor will the 2ndry switch, only the CTS.

Thjat said, code 44 lean exhaust and pinging/detonation is probably related.

I'd do a search on the TPI forum for code 44 and go from there.

spearson

Sometime ago in my cars past it was wrecked (looks like it was frontend damage) and the duel fan was replaced with a single fan, but I have the plugs for both fans hanging there. How do I tell which is the correct plug to use? Also, at what temperature should the fan turn on? is it 230?

One more thing, whats the easiest way to get the 02 sensor out? It is too tight to get a wrench down there, and a socket wont work because of the wire coming off the sensor.

8Mike9

I don't recall what the on-off temps are anymore...something in the 220-230 range...I replaced my 2ndry switch with a 200-on, 185-off switch, which overrides the whole ECM control of the primary...been like that for so long I forget the ecm control values.

As far as telling which is which, on my '89 the fan on the drver side was the primary, so maybe you can tell which plug went to which side? Or you may have to do some wire tracing...the plug going to the relay that is contraolled via the fanswitch between #6 and #8 is the 2ndry.

Re: The O2 sensor, get a 1/2in ratchet, and a 12-inch extension and go after it from the front, under the manifold, should be plenty of room to break it loose and get it out.

spearson

What about the wire coming off the o2 sensor, that gets in the way of the socket, or does that wire come off?

thunderstick

no, the wire doesn't come off. you can either use a wrench (easiest from under the car), or there is a "special" socket that goes over the wire, just can't remember what size... you can get it at parts stores, but i'd try the wrench thing first.

KAM

spearson

It is 7/8 inch. I tried a wrench, I couldn't get at it from any angles. Air lines, brake lines really get in the way.

8Mike9

Ya...get a 1/2inch drive ratchet, 12 inch long extension, 7/8th deep socket and the 7/8th deep O2 sensor socket.

Come in from the front with the standard socket, just clip the O2 wire off.

Remove the O2 sensor, then remove the 7/8 standard deep socket and put on the O2 sensor socketand slip the wire in the slot and tighten it up.

I've seen the cheepo O2 sensor sockets start to come apart on tough sensors when trying to take them out, that's why I only use the O2 sensor socket to install'em.