ja78911sc

I have been experiencing cold idle issues (cold only).

I ran the scan tool test and the results consisted of:

My cylinder head temp reading did not change when I ran the actual value test with my scan tool. 117 was the value and it did not change. I started with temps just below 8 and let it idle to 8:30. around ten minutes.

I am assuming if the value remained the same the sensor is toast?

Also, my intake air temp remained at 44. Is there a sensor for this as well?

I checked all of the boxes in the actual value area. The other values had readings that varied with idle, etc.

Thanks......

Ducks964

The air intake temperature sensor is in your Air Flow Meter.

ja78911sc

Thanks. I am assuming this value should vary not remain constant?

JasonAndreas

Both temperature sensors are NTC sensors so the only way they should remain constant is if somebody put a fixed value resistor in their place.

ja78911sc

Jason, thanks for the response. Why would somebody install a fixed value resistor? So you don't believe the fixed value is a symptom of a bad sensor? Thanks again for any input.

PhatPhlatSix

A disconnected sensor might read full scale. Try disconnecting the air-flow meter to see if the reading changes.

A temperature sensor is a resistor that varies with temperature. If you look at the airflow meter plug, i.e. on the housing, there is a pin missing. The pin next to that (pin 4) is ground. Pin 1 (furthest away) is the NTC sensor. I measured the resistance between the 2 and it was around 2.8kohms at 16°C. Might be interesting to see what yours reads.

ja78911sc

My cylinder head temp is reading 117. I believe full scale would be 244.

I am not sure what full scale would be on the air intake temp sensor?

RichieRoo

Coincidentally, I measured my cylinder head temperature yesterday using the Durametric tool because I am experiencing cold start issues.

Here are the results with a warm engine
Engine temperature
117.8

Intake air temperature
63.2

Oxygen sensing
1.01

I'll check the readings when cold in just a few minutes.

RichieRoo

OK... here are the results from the cold engine

Engine temperature
42.1

Intake air temperature
26.7

Oxygen sensing
1

Here's the values as it warms up for a minute

PhatPhlatSix

Interesting. What tools are you using:
a) to access the ecu data
b) to log the incomng data?

JasonAndreas

Various tuners & mechanics have done it over the years trying to resolve other issues and its also been done in PCA racing... The only semi-legitimate reason would be for a MAF but then you lose temperature related ignition timing
reduction.

Anything is possible but resistors have 3 modes of failure; if it short-circuits it would have zero resistance, open circuit would be infinite resistance and the third being drift. The ECU is pretty good at detecting the first two and if it did, the default values would be;

CHT: 0x1A = 26 = 3.9F
IAT: 0xB7 = 183 = 184F/20C

Do you have an ohmmeter/multimeter? You can measure the resistance of the CHT sensor at the white connector on the left rear of the engine compartment. You can also remove the CHT sensor and put it in boiling water.

How close to ambient temperature does the IAT read on a cold engine?

RichieRoo

PhatPhlatSix – I'm using Durametric kit, I believe that ja78911sc is using the Scantool kit. I just use Excel to plot the graphs.

I'd guess that mine is behaving correctly (I assume the spike is just an anomaly). I think my problem could be that I just need to perform a 'system adaption'.

ja78911sc

Yes, I have a meter. This was my next step. I was just curious if I could use the scantool to determine if the CHT was operating correctly.

I just ran the test cold:

IAT 26

CHT 37

The IAT climbed to 31 warm at idle no driving & CHT climbed to 117 warm.

It appears it is operating and the max is 117. Do these numbers look good?

Lorenfb

Do as Jason suggested, i.e. use an ohmmeter to measure both sensors cold and hot.
That way you can have an idea of what the actual values are compared to the scanner values.
Also, when the sensors are disconnected for an ohmmeter reading, see what the scanner indicates.
The CHT sensor usually varies from approximately 2-2.5K cold and 100-300 hot. You also get
a 1/2 watt resistor (1K ohms) and insert it into the CHT and see what the scanner indicates.