Hey y'all. Hope everyone's doing great on this mother's day. Couple things here that I hope you can help and guide me with. I've owned a few of these trucks, but never really had to work on them.

Drove the truck for about an hour and a half this morning, IAT temps kept rising, hitting about 145 degrees when I got home. I'm not sure if that's normal, but in my 14 years in the automotive industry I've always seen and heard it should be about 10-20 degrees above ambient temp, for those sensors that are in the intake boot and not on the actual intake. I replaced the thermostat because it appeared to be bad, and the IAT rose to about 160 before I shut the truck off. So I'm concerned here that it's bad. If I unplug the sensor, it defaults to -40 degrees.

Now to the ECT...I replaced the thermostat because it had some strange running symptoms and watching the temp on my scan tool after about 4 minutes of driving it showed 181-188 degrees, then stayed about 181-184 degrees. Never got above 188. I thought maybe someone replaced it with a cooler thermostat but it was a 195 when I removed it. But after replacing it, it was getting up to temp in a normal timeframe. It would hit 194 then drop ro 188/192 then up. After I put the radiator cap on it slowly went up to 199 and the IAT temp went to 161 degrees.

I'm not sure if something else is going on or not. I'm curious if it could be a fan clutch issue. Sometimes it'll run smooth as silk, and then other times when you're driving you'll hear a huge rush of air before it shifts. I've never done a fan clutch, so I don't know the symptoms of these trucks to tell when they are bad.

Sometimes when driving the engine bay gets really loud on acceleration, and sometimes it takes forever to get to highway speeds. No engine light, no codes. It's hard to describe. There is a little bit of play in the fan clutch it wobbles if you move the fan front to back.

Sorry for the rambling and randomness. Point is, is the IAT supposed to read that high? Do I have some other sort of problem? I'll try to answer any questions the best I can. Something's not right.
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How close to ambient are those two sensors on a cold engine with key on?


George

 

Checked this morning after it sat for 12 hours and had just fired it up and the ECT showed 65 and IAT showed 60. It's 56 degrees here right now. My wife's Sonata has the IAT in the manifold and it never gets that hot. But yesterday it was up to 160 degrees on IAT temp and that concerns me, especially since it's in the intake tube down by the maf. I used to buy and fix and sell cars for 14 years and have owned close to 200 cars, and any that I've ever done live data on have showed 10-20 degrees above ambient temp. But I know every car is different.

 

I was looking for the cold engine key on readings not after the engine was fired up. I was trying to see how well your AIT correlates to a known ambient condition in a cold electrically quiet environment. I believe that this sensor just pulls out of the flexible horn so that's another way to check. Your readings at temp are high so the question is why? First check the air horn for cracks or poor seal at the clamp etc to make sure your not bringing in direct engine heat. Next up is wiring and of course the sensor itself. Make sure you have a good ground and then you can also test the tan wire from the sensor to the VCM ( C2 P22). This should be done under the conditions where the readings are very high. If your a parts cannon guy then of course you can try a new sensor.

What are your 4 fuel trims when the AIT temp is at its peak?


George

 

I stressed the IAT in my blazer pretty good today as a check. Truck idling no movement 85° Florida sun air conditioning on Max nose of the truck near the garage door to minimize airflow. My ECT stabilized at 194F in my IAT maxed out at 124F.


George