Temp sensor out of range!?!?

[Vanner1993]

I have been getting worse fuel mileage than my van, along with failing inspection at idle. Ran codes, Temp sensor out of range. I just replaced it when I did the heads so it is brand new. But the computer still thinks it is bad. What else can cause this? Is there a test I can do to see if there is a short? I was told it can be in the processor, can it? I have a machine at shop that shows exhaust gases, above 1000rpm the hc's are in range of 220, at idle about 800 rpm the hc's jump to over 1000. It does not run rich when high idle, only at normal idle.

 

[kimcrwbr1]

Did you bring it up to temp before running the codes. If the engine has got hot it could have ruined the sensor. Disconnect the battery for 30 minutes and then drive it around at medium speeds for 20 minutes then run the codes again when it is up to normal temp.

 

[kimcrwbr1]

While you have the battery disconnected clean the intake air temp sensor with rubbing alcohol or elect cleaner I believe it is in the duct going to the throttle body it has two wires like the temp sensor.

 

[jhammel85]

Don't forget to check the wiring to the sensor as well. Perhaps something broke during the head swap or at any other point. It'll run rich if that sensor is bad or disconnected.

If it comes to a new EEC, I'm getting ready to put two for an 87 4x4 up for sale. One with a Jet chip for 30 shipped and another bare bones stocker for an 87 for 20 bucks shipped.

 

[Earl43P]

http://therangerstation.com/tech_library/EDiagrams/files/Diagrams_ElectronciEngControls2_9_2of3.JPG

That link shows which wires go to it, so you can test them for continuity.

http://fordfuelinjection.com/?p=28

 

[Vanner1993]

I am gonna look at it tomorrow, I am gonna check the wires, test them and hopefully it's not the computer. A JET chip would be sweet tho haha.

 

[Vanner1993]

The computer side of the sensor(green wire) reads 4.16 so about 5 volts. That is bad, so I tested wiring and it is good. Brought it to a shop and checked it out. Said it's either the O2 sensor wiring such as burned on exhaust or the computer. I went under the truck and took a look after I got home and wiring is just fine, actually nice and clean as if recent. I am gonna do tests at school through the breakout box again and scanner...I just hope it is the computer so this issue is done and I can pass inspection and I will be done getting stopped by police. I am only getting one code, code 21 Coolant Temp Sensor Out Of Range. Sensor is brand new, wires are good, just getting full richness.

 

[Vanner1993]

The signal return on the temp sensor ended up being a bad wire, I spliced in a new one and there is no more code 21. But I ran codes again and code 42 came up now which is O2 sensor always rich. This must mean my O2 sensor is bad? I am still getting over 1000 HC's at idle but no more code 21.