Temp II replacement

[hbueno]

My 84 has been running rich since I got it in January. From reading the forums, one of the possible culprits is the Temp II sensor. I finally got around to testing it with a multimeter. Measured resistance from each pin to ground and the reading for each indicated open circuit. I've placed an order for a new sensor.

Any gotchas I should know about when replacing the sensor. or is it as straightforward as it looks?

Hugo

[kelanel]

pretty straightforward, dont forget to replace the crush ring (900 123 101 30) that goes with it. waterbridge is lightly pressurized even when cold so have some towels handy (and a spare finger to plug the hole for minimum spillage).

[hbueno]

Turns out the Temp-II sensor is fine. The test procedure I found in another post is for LH-Jetronic systems where the sensor has two outputs. The Temp-II for L-Jetronic systems is tested my measuring resistance across the terminals.

Back to the drawing board....

Hugo

[kelanel]

o2 sensor and AFM come to mind. otherwise potentially faulty L-jet. rich at idle, semi throttle or full throttle?

[hbueno]

I notice the telltale smell of a rich running engine when I pull into the garage after a drive. I don't think it's a major problem considering there's no black soot coating the area around the exhaust outlets like I've seen on one thread here.

In terms of possible symptoms, the only other thing I have is a slightly lumpy idle.

Next step is testing the O2 sensor. I hope the thing isn't rust welded in place.

Hugo

[jstobo]

You tested the Temp II sensor correctly. The two prong on an 85 is tested the same way. pin-ground. The Temp II sensor has two prongs on the 85 because the sensor sends one temp signal to the LH computer and one signal to the EZK computer. The 85 also has another temp sensor that goes to the dash gauge. If your temp II sensor is open circuit from pin to ground it is bad.

According to the WSM an infinite ohm reading(open circuit) means a excessively rich mixture, engine will not run warm and can not be started. For a short circuit(0 ohms) mixture too lean, no pickup in cold state.

Hope this helps.

[hbueno]

The 84 is L-Jet, not LH, so the Temp II is definitely tested differently - i.e. resistance is measured across the two pins, not each pin to ground.

I started suspecting as such when I tested the new Temp II that I purchased and it was open circuit from each pin to ground but had proper resistance at various temperatures when measuring acorss the two pins.

Hugo

[harborman]

Mine ran rich when I got the car. I ran about two bottles of Techron in it and after a short time it cleared up and runs fine now. Something simple to try anyway.

[hbueno]

I'm already on the first bottle of Techron so we'll see how it goes.

Hugo