sharkmeister85

Hi All!
Is there any way to test or tell if your Temp II sensor is functioning correctly? Could a faulty one effect (raise) idle speed as the engine warms up? TIA
Glenn

John Speake

Hi Glenn,
Idle speed should be constant 675rpm auto, 775rpm manual.

Temp sensor 2 tests are in the workshop manual, aprrox 1.4 - 3.6 kohms at ambient temp, measured from each of the two terminals to the block.

sharkmeister85

Thanks for your reply, John! I will test that this weekend.
As you probably guessed the idle on my '85 MY has recently become too high when at operating temperatures (about 1050-1100 rpm). From looking through the archives, I thought I saw something about the Temp II sensor being able to turn on the auxilliary fan after shutdown if the manifold temperature was above a certain value. Since my auxilliary fan always shuts off if I turn the engine off, I'm looking at it as a possible culprit here.
However, I guess some sort of vacuum leak has to be considered my next suspect. Coming to a stop, the idle slowly returns to the new higher rpm. The ISV is less than 2 years old, so I assume (dangerous) that it is okay, but thought maybe one of the hoses attached to it could be my source of vacuum loss. I couldn't see or hear anything in that vicinity( though that doesn't rule out a vacuum leak still from there). From the archives, I tried isolating the ISV by jumpering the 1 o'clock and 6 o'clock pins under the cover of that terminal beneath the shock tower brace. I expected to get a lower idle speed, but in fact, the idle climbed. Not sure how to interpret that.
The car starts from cold readily and will idle steadily at about 700 rpm. Starting up at operating temperature can be hit and miss, with significant hunting and possible stall if the gas pedal is not used. Warm or cold, the rpm is pretty steady, no hunting. Due to the change in weather here, I recently discovered that setting the lower slider on the HVAC unit to the far right defrost setting will bring the idle down noticably. Another factor saying vacuum leak? Maybe I have more than one trouble spot.Any thoughts? Anyone?
Thanks,
Glenn

John Speake

Hi Glenn,
I'm not sure about your '85 (early 32v ?) as far as the auxillary fan is concerned. the late Euro S2 (MY'86 have an seperate temp senor on one off the Spider's legs, which tunrs on the auz fan if temp is higher than 90 deg C.

I am not too conversant with the idle system on the early 32v motors. But it does sound as though the vacuum leak theory may ve worth investigating.

Good luck !

Rich9928p

For all LH systems, the correct Temp Sensor II value ranges are:

0 C / 32 F: 4.4 - 6.0 k-ohm
15 – 30 C / 59 - 86 F: 1.4 to 3.6 k-ohm
40 C / 104 F: 0.9 – 1.3 k-ohm
60 C / 140 F: 480 – 720 ohm
80 C / 176 F: 250 – 390 ohm

Measure the ohms between a chassis ground (preferably on the engine near the sensor) and each pin, not between the two pins. There are actually two different sensors (hence the name), one sensor is for the LH and the other is for the EZK module. Both modules use engine temperature as part of their data input. If either sensor is not working correctly, the engine may not run correctly.

Another suggestion, also measure the resistance at the LH and EZF/EZK connector. This way you determine if there is a problem with the wiring between the sensor and the control unit.

For the 25 pin EZF, it is pin 23
For the 25 pin LH, it is pin 2

For the 35 pin EZK (S4 and newer), it is pin 19
For the 35 pin LH it is pin 13

The same rule applies, use a chassis ground for the negative probe of your Ohm meter.

sharkmeister85

John and Rich,
Thanks for the data. Looks like my Temp sensor II checks out okay. Guess I'll have to do some real work checking for vacuum leaks.
Glenn

SteveG

Would that be the idle control valve? They are usu gummed up by 90K and need replacing. Because of a vacuum leak (the line off the oil filler tube that runs under the intake was the culprit, it disintegrated, looked like someone poured acid on one side) that is unreacheable, I had the top off, so I replaced both. ICV may have been ok, the hiss from the line was prominent. Between the two I had rough cold idle, would have to feather the pedal for 3 minutes til it warmed up. I also had loss of power at speed, but I'm pretty sure that was from a corroded coil wire. HTH.

sharkmeister85

SteveG,
Yes, I believe ISV = ICV. Mine was replaced less than 2 years ago, so I am sort of assuming its okay. I know the line that runs under the manifold from the oil filler neck. Mine blew about a year ago. What was left was like chewing gum! I can't hear any obvious vacuum leaks, so it must be smaller, slower culprit. I guess I will have to get a Mity-vac and start going over the lines one by one. I will probably have to pull the intake, its pretty grungy in the valley and the intake could use refinishing anyhow.
Glenn

bobraney

Sharkmeister:

Let me know what you figure out. I have the same problem in my 86. On cold start my idle is 650, increasing to 900 when warm. No surging or hunting except briefly when quite cold.

My Temp II checks out OK. Also, I just had the intakes off replacing some rotten breather lines so I checked and cleaned the ISV and it appears to be OK. I also checked all the vaccuum connections. I'm running out of ideas about what to check next. I might check the voltage at the brain to see if the TempII signal is getting through.

Thanks,

Bob.https://rennlist.com/forums/newreply...e=1&p=1573313#