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post #1 of (permalink) Old 12-19-2000, 08:48 PM
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ACT Sensor???

I just pulled the EEC-IV codes off my 94 302 efi and came up with a code of 113 witch is a ACT (Air Charge Temp)sensor circuit open or reads -40F. My questions is what is that.

I read from http://www.autoweb.lycos.com/garage/subsys/bamanifo.htm

This sensor sends a signal to the computer in relation to air temperature in the intake manifold. On some engines, the ACT sensor is mounted in the air cleaner.

The MAF sensor transmits a signal to the computer in relation to the total volume of air entering the engine.

What is that doing to my Bronco, I've never felt like I'm getting full power from the 302 but it runs like a top minus low end torque issues, no other problems and I want to keep it that way. Can I fix it, should I fix it, is it that sensor on the top of the air cleaner. anything will be helpful.
Thanks in advance
Sorry for the Long Post.


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post #2 of (permalink) Old 12-19-2000, 09:52 PM
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Re: ACT Sensor???

On early (MAP) 5.0L's, the ACT was screwed into the intake manifold on the driver's side in the 4th runner from the front. I think it has only 1 wire, but I don't remember the color. The element is exposed in the airstream, and is very fine, so it may well be broken.

It should definitely be replaced, and should be easy and cheap. The engine is running in the "limp-home" mode, which may be the reason for the poor performance.

Steve
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post #3 of (permalink) Old 12-20-2000, 10:42 AM
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Re: ACT Sensor???

Well I did a little calling and no one but the Dealer has ever heard of an ACT sensor. They Want $47.38 for the sensor so not as cheap as I thought but still not that bad. My questions is still where the Sensor is located. There is a sensor on the Air box above the filter and one above the airbox closer to the intake. I guess I'll figure it out when I get it but Help is always appreciated. Has anyone else ever replaced one and what difference did it make.

TIA

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post #4 of (permalink) Old 12-20-2000, 11:01 AM
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Re: ACT Sensor???

The ACT (or IAT) is a 2 wire sensor. It can be in the air box, or threaded into the lower intake manifold (between #5 &6)runner. If you are reading open, the sensor wire is probably broken, or corroded too much. Between the air box and throttle body will be the MAF sensor, it has 4 wires for your year.

post #5 of (permalink) Old 12-21-2000, 03:51 PM
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Re: ACT Sensor???

I'm replacing the ACT sensor tonight, my other question is would that cause my exhaust to smell like a burnt catalytic converter, rotten egg smell? Or is that another issue. I'm noticing the smell alot more since the weather got cold.

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post #6 of (permalink) Old 12-21-2000, 04:33 PM
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Re: Exhaust Smell

It may be related, or it may be bad gas or a bad converter. The EGR system also affects the type and concentration of gasses in the exhaust, so check it if it doesn't clear up after the new sensor.

Steve
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post #7 of (permalink) Old 12-23-2000, 01:47 AM
 
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Re: ACT Sensor???

If the ACT or IAT sensor is open it is telling the computer that the air charge is maximum cold and therefore very dense so the computer tells the injectors to squirt more fuel. This results in a rich mixture at lower engine speeds which, in turn, beats the hell out of your low end torque. As you increase speed the mixture is still rich but the effects are not so noticeable

The sensor should be mounted on the intake tube somewhere between the air cleaner and the MAF sensor. As the air temperature increases the IAT resistance is supposed to decrease. I'll bet yours reads infinity at any temperature.

By the way, after you replace the sensor, the computer will take 10 to 20 miles to "relearn" everything it memorized in the last 10 to 20 miles.

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post #8 of (permalink) Old 12-23-2000, 11:34 PM
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Re: ACT Sensor???

I've read and been told by Ford-trained service techs that the computer can distinguish between a sensor that is indicating -40 degrees and one that is open. If the sensor is bad and indicating -40, this would occurr. But if the sensor is open, the computer will "limp home". I've never tested this myself with a bad sensor and an open sensor, but it's what I've been told.

Steve
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post #9 of (permalink) Old 12-24-2000, 12:04 AM
 
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Re: ACT Sensor???

You may be right. I'll dig around and see if I got an old unit. If so, I can take it into my lab, do a temperature profile then see what the computer does under different simulated conditions.

I'm interested because I have an EEC IV engine and I have no urge to get stuck in the boonies because of a bad resistor.

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