02 Sensor Issues - 87 3.2

[tx63conv]

Help me think through 02 sensor issues for my 87 3.2. I posted earlier that I was having off idle issues until the car warmed up--it will stumble and even backfired once when I gave it a lot of throttle. Once at temp, it will eventually accelerate fine. I read an article on the Pelican (referencing a 944) about symptoms of a failed sensor which include engine not accelerating.

https://www.pelicanparts.com/techarticles/Porsche_944_Turbo/69-EXHAUST-Oxygen_Sensor_Replacement/69-EXHAUST-Oxygen_Sensor_Replacement.htm

I hate to throw parts at an issue but not getting a lot of suggestions. I have checked for vacuum leaks.

As an aside, I used some break cleaner under the car after an oil change to try and clean some things up. Not sure if that could have harmed the sensor. Also, not sure the last time it was replaced (111k miles).

[proporsche]

ok what hapen when you disconnect the oxy sensor?
ivan

[Classic11]

Hey, the o2 sensor is likely not the issue, it does nothing in idle (when idle switch is actuated) and in WOT (when WOT switch is activated), only in "cruising.
Please let us konw a little more about the issue and symptoms.

[hcoles]

I had this and it was the cylinder head temp. sensor.

[mysocal911]

Originally Posted by Classic11

Hey, the o2 sensor is likely not the issue, it does nothing in idle (when idle switch is actuated) and in WOT (when WOT switch is activated), only in "cruising.
Please let us konw a little more about the issue and symptoms.

That's not correct! The O2 sensor always has an effect except during the warm-up mode and at WOT.

[tx63conv]

I have not had a chance to disconnect the O2 sensor. Will try when I am back at my shop on Friday.

Car ran fine (had a non start issue and changed the ref and speed sensor) back in the summer, has run fine since
Recently changed oil, sprayed some brake cleaner on underside of engine to clean
At startup, starts fine, idles at 900 however any gas the car begins to stumble, wont go past 1100 rpm; idles a little higher at 1000
After full warm up, can give gas but stumbles from 1100 to 1300 then revs fine
After a few times of this, car revs as normal

I have looked for vacuum leaks, checked seal on oil filler, added new gas. I have a 2 wire CHT so I believe it has been replaced but not under my ownership.

[tx63conv]

Originally Posted by hcoles

I had this and it was the cylinder head temp. sensor.

See my further explanation. Was yours similar?