Correct /expected Intake air Temperature

[osullivant]

I am having nightmare time analyising faults in car, getting to be undrivable in the city but fine on the motorway.

I had a brainwave tonight that maybe it was the intake air sensor givng a bad read. having driven for an hour the ambient temperature was 17c , the coolant was at 86 and the IAT was 41.2 is this a normal range. if not what would be ... when the car is cold in the morning I presume this IAT should be less than or close to Ambient before start up and should rise in tandem with the coolant temp.

Not in a position now to go out driving to experiment but am very curious....

Tony.

[5cilinder]

The difference in ambiant and intake temp is usually between 3 til 12 deg celcius in difference.
Factors impacting intake are boostpressure ,speed(coolflow) airco usage and state of the intercooler
Sometimes if the engine is shutoff hot and started an hour later the difference will be much higher a short time because of heatsoak

If the intake temp is too high im not surprised that power can be capped

[osullivant]

Originally Posted by 5cilinder

The difference in ambiant and intake temp is usually between 3 til 12 deg celcius in difference.
Factors impacting intake are boostpressure ,speed(coolflow) airco usage and state of the intercooler
Sometimes if the engine is shutoff hot and started an hour later the difference will be much higher a short time because of heatsoak

If the intake temp is too high im not surprised that power can be capped

Thanks.

That makes sense.

Intercooler is new and clean. Turbo is effectively new. Intake manifold is clean as are all pipes air filter etc.

With a difference of 25c according to the sensor if may well be that this is my problem
I'll know better in the morning. But this sensor was removed when I was working on the engine and may well have been damaged, or got wet or dirty.....

Regards .

Tony

[cheshired5]

IAT should be ambient temp on a stone cold car before starting the engine. Same with coolant temp.
At constant cruising speed, my IAT is 4-5°C higher than ambient, 3°C higher in winter.
My IAT sensor is built into the MAF.

In summer, with a hot stationary engine, 25° difference doesn't sound completely out of the question.

[osullivant]

cold engine ambient temperature of 13 degrees IAT 37C. This appears to be a problem...... but where is the sensor on the 185.... only sensor I can find in the intake manifold is the camshaft position sensor....?

[cheshired5]

The temp sensor will be in the MAF or MAP.
What is your MAP psi engine off ignition on?
Then what is MAP psi at idle, 1,2&3k revs?

[osullivant]

As I understand the function/nexus between MAF fuel mix etc the IAT sensor must be post intercooler/turbo, as the real measurement required is the air temperature as it gets dumped into the cylinders.

The only sensor that seems to fit this position is in the side of the intercooler so I guess this is a combined map/iat sensor certainly some confusion on sites as to what they are selling but many showing photo of same article with same bosch number . 0261230 106

Numbers as per Torque.

at KOEO IAT 39 c Idle 39c. 1000 39C. 2000 40c 3000 42c.

MAP PSI KOEO 14.9psi, 15.7 at idle, 15.1 at 1000, 16.4 at 2000 and 20 at 3000.

Thanks..

[osullivant]

UPDATE.

Removed sensor (from side of intercooler) when disconnected temperature of minus 40c with audible warning of icy conditions. cleaned and reconnected temperature dropped to 37 and when blown on with hot breath rose up to 42 to 43. settling at 25 above ambient...

Almost certainly the correct sensor and almost certain that this sensor is faulty... I just need to find one to try in its place.???

Thanks

[5cilinder]

The sensor in the intercoolerside is a combined pressure /temperature sensor and yes its probably faulty with those readings (or its cranking crankcase fumes like crazy)
Whats the reading with cold engine and no running engine? key in 2

[cheshired5]

Originally Posted by osullivant

As I understand the function/nexus between MAF fuel mix etc the IAT sensor must be post intercooler/turbo, as the real measurement required is the air temperature as it gets dumped into the cylinders.

Not necessarily.
As mentioned, my IAT sensor is in the MAF so very much pre turbo and i/c.

Yours is a later D5 though and appears to have a TMAP sensor and the T element sounds knackered unfortunately so in your position, I would change the sensor.