[kainers]

The MAT sensor on my truck reads 115 cold start and goes to 145 driving.I think it is toasted but wanted some trouble shooting technics to try before buying another one.I pulled the chip and the same results apply.Is there a measure ment I can do with a multimeter or Ohm it out some how.

Thanks

Mike

 

[klhansen]

Mike, the MAT is used by the PCM to control injector timing.

My service manual doesn't list the resistance/temp chart for the MAT, but I'm pretty sure it's the same sensor type as the Intake Air Temp Sensor, and there's a chart for that one. I think it'll get you close.

Pull the sensor out, connect your mulitmeter to it and expose it to some different temps (ice water, boiling water, etc.) and see what happens. Could be a problem in the circuit too. If the sensor shows different resistance at different temps (indicating it's working), check the wiring.

IAT data
<font class="small">Code:</font><hr /><pre>kohms IAT (Volts) Degrees C Degrees F
1.19 0.28 120 248
1.56 0.36 110 230
2.08 0.47 100 212
2.80 0.61 90 194
3.84 0.80 80 176
5.34 1.04 70 158
7.55 1.34 60 140
10.93 1.72 50 122
16.11 2.15 40 104
24.25 2.63 30 86
37.34 3.09 20 68
58.99 3.52 10 50
</pre><hr />

Note that you won't be able to read volts unless it's hooked to the PCM, just use the kohms.

Just my guess, but you'll probably find the sensor pretty close. They are just about dynamite-proof.

Good luck

 

[kainers]

Thanks

 

[kainers]

11.2 at ambient temps of 80 degrees I just threw it in the freezer see what she reads here in a few minutes.Well the MAT must be good cause it went to like 72-69 in the freezer.I have tried to chase wires but what am I looking for in colors back to the pcm?

Could the PCM be starting a downward spiral?

 

[kainers]

Well Found the problem.After not finding any wire chafe and checking the intake air temp to compare.I pulled the Taper core.There is so much mud and bugs in between the fins I couldn't even get water to pass through them.Found a dead bird and a crud load more bugs between the AC and the Inter cooler and another set of filth between that and the radiator.

Gonna take me awhile to get this cleaned up.