928 at last

Hi All,
On dissassenbly of the intake, the internals on the sensor were rotating and not the housing (22mm nut). I suspect this may have, pardon the inference here but...."Rogered" the sensor unit . Is there a test procedure for this sensor, or am I just better off replacing for insurance reasons if nothing else?
TIA,

Jim M.

Without knowing what is inside the sensor or how it works, I'd replace it just to be safe. It provides info to the fuel computers.

the flyin' scotsman

I'd just replace it rob.

BTW what year/model is your car?

jpitman2

Which system are we talking of here? AFAIK L-jet has a temp sensor inside the AFM , which if it fails makes the whole AFM toast, and LH automatically reads air mass, and doesnt need to read temperature. The temp sensor on S4 inlet housings, IIRC, is used to trigger cooling fans in case the coolant temp sensor hasnt, in cases like heat soak.
Anyway, most Bosch temp sensors have resistances that go from ~3k ohms cold (<65F ?) down to ~300 ohms fully warmed up, if thats any use.
jp 83 Euro S AT 52k

Tails

HVAC outside temperature sensor. If this is what you are talking about.

The outside temperature sensor is located front left in alternator's cooling air hose. Electric onnnection is made with a 2-pin plug in the left headlight housing and a 4-pin flat male plug behind the right centre console trim panel.

Remove trim panel on right side of centre console.
Disconnect 4 pin plug (term. 3/4 both with yellow wire).
Connect ohmmeter (range : x10) on terminal 3 (yellow) and 4 (yellow) on socket end of plug.

Ohmeter should display the following values:
approx 933 ohms at 0 degrees C
approx 588 ohms at 20 degrees C
approx 457 ohms at 30 degrees C

Important: To change the resistance, the cooling air hose can be disconnected on the alternator and air blown into the hose with a hot air blower (wife's hair dryer) and the display value must drop.

If you are already have the temperature sensor out of the alternator cooling air hose then just use the ohmmeter directly onto the two pin connector of tail wire of the sensor.

To allow us to give an informed diagnosis and therefore assistance, we require the MY (model year) and whether it is a manual or automatic.

Tails 1990 928 S4 Auto

dr bob

Still noy such a bad idea listing at least the year of car you have, maybe in your signature. "Intake temp sensor" means different things on different cars. For S4+ cars, this is a switch tied into the fan controller. Some earlier cars have an actual temp transducer in the air cleaner housing.

So watch'a workin' on?

Mike Frye

I found another post by Rob in which he says he says he has a 90 S4.

If it's like the S3 the IAT sensor can be tested as part of the fuel injection test plan. It should test within a certain resistance range based on the ambient air temp. I'd just replace it if it's physically damaged though. It could read fine now but when you hit a bump or the temperature changes it could go open or shorted and be giving your car bad readings. I think it's a trigger for dailing back the ignition timing if the intake temp is too high.

dprantl

This is only on the S3. On the S4+ the only function for the intake air temperature sensor is to turn on the cooling fans when the intake air gets too hot. I wonder, has anyone tapped into this sensor so they could display it on a gauge in the car?

Dan
'91 928GT S/C 475hp/460lb.ft

blown 87

Rogered? is there a story behind that?

John Speake

If this is the sensor at the back of the inlet plenum on an S4, then it is a switch, not a temp variable resistance. You can test by dunking just the tip in boiling water. It should switch (s/c) at about 90degC IIRC

Tom in Austin

I think the switch on top of the intake is just used by the cooling fans. Temp II and one or more other sensors drive the fuel and Ign computers.

the flyin' scotsman

Some weird Python type fable involving ............Wilco

If the sensor/switch in question is that on the rear of the intake of a +'87 car then its ~$30 so no brainer............replace and forget it.

John Speake

That's correct.....

928 at last

Thanks everyone for the responses.
A few notes:
i). Ive said this before, but we gotta get a spell check on these threads.....it gets embarassing when you're typing quickly and subsequently see what you think you've typed, not actually what's on the screen.........
ii). For some reason...and this is again a case of really bad proofing, I had thought that the details on my car were in the sig line. Think I've got it covered now! P.S. Thanks Mike for checking and letting everyone know.
iii). Malcolm, sorry, see point (ii) above.
iv). Dr. Bob, please also see above, and thanks for the PET pdf file.
v). It's the fan/flap sensor unit.......I'll test it but it's going in the spare box. New one to be ordered. Thanks John for the trip temperature.
vi). Malcolm, no storey as yet.....just an "Englishism" as I'm sure you're aware. If the Scots use it too don't be offended, I just haven't heard it that way.........
for everyone else, "see also"
"F*&$%ked"
"F*&$%ked-Up"
In my case at least this time around, "F*&$%ked - It - Up"......
And any other various and sundry euphanisms referring to the act of copulation.
(Between consenting adults only of course).
Back to the Python reference though........
For those are keen on a dry sense of humour, the potential here is enormous.

the flyin' scotsman

There's actualy a great Python skit regarding WW2 flying ( hence my Wilco response to Roger).............thats where Tony H got his avatar from.

Can read the sig now...............'90 S4.........well done old chap.

On topic..............the part I believe you started this thread about is 928 606 217 00; good luck bombs away.