I am having odd issues with my 1997 Discovery 1.
The Intake Air Temperature sensor is all over the place. I put a new one in, did not change anything. When the air temperature outside is 70 degrees, it will show anything from 70 to 104, vehicle speed, shade, engine temperature have no correlation. Air intake is clear.
Also, the ignition advance is odd (this is distributorless). At 800 rpm idle, it shows 20 degrees, at 2000, it shows around 30; at 3000 it makes it to around 39 degrees sometimes, but when you let it idle back, the advance does not come back.
The engine runs ok without load, but is sluggish when cold, and will not rev past 3000 rpm going down the road.
I am thinking the issues point to a problem with the ECU, and a trip to a specialty shop is in order, to get into the ECU, or possible flash a replacement.
Anybody have any thoughts?

 

you're probably on the right track with a reflash...you could take out the ecu and make sure it isnt wet inside...that's a common issue and could cause all kinds of bad things...FWIW though...I had the same issue with my '98 >>>the air temp sensor claimed it was -105 below zero .....LOL !...replacing the sensor wasn't the answer....the ecu was at fault

 

More information, , ,tracked down to getting 1.2 - 1.5 volts at the IAT, book calls for 5 V. I pulled the ECU out, everything pristine inside, no corrosion, discoloration, etc. anywhere, plugs and connectors all tight. The IAT gets this voltage from the ECU, so I am thinking there is a voltage regulator in the ECU itself that has failed, and a new ECU is in order. Thoughts?

 

Latest update, , ,changed ECU, didn't resolve it. Checked every possible connection, etc. . .no problems found. Talked to a local independent rover shop, he suggested Crank Position Sensor, , which I had recently replaced (turns out time flies, 2 years and about 20k miles). We went through everything else again. What I had read was that the crank position sensor either works or it doesn't, they don't "kinda work". Well, , ,we decided to throw a crank sensor on there just to see. . .problem solved! So, if someone tells you "if it runs, it isn't the crank sensor", , ,that isn't necessarily true!

 

Thanks for following up with the resolution of the problem. These types of posts are particularly helpful.

 

After those voltage readings I was gonna suggest you had a short

 

Hi all. I'm having a similar issue and was hoping someone might have some advice.

Computer is reporting that the air from the Intake Air Temperature Sensor is -40 degrees F when it's 80 degrees F.

I tested the resistance of the sensor and it was reading 440 (seemed about right considering the heat under the hood, 440 mapping out to about 135 degrees).

With the key in the On position the Red-Black wire had 0.2v (pretty sure it should be the 5v reference as per the wiring diagram).

The Grey-Light-Green wire that I believe should be the reporting channel is reading 5v.

Any advice/guidance would be greatly appreciated =)