What are the sensors on the air intake hose?

[Nathan123]

I have a 99 ranger with the 4.0 liter (SOHC). On the air intake hose, their are three items, starting on the left, there's the MAF, then a hose going to the oil fill tube, and then, right next to the throttle body, a rubber boot with a sensor and a wire coming out of it. I understand the MAF, but what are the other two, particularly the sensor?

 

[gwaii]

the sensor is the air charge temerature sensor,it tells the computer what temp the air is.
the tube is the air inlet for the pcv.

 

[Nathan123]

Thanks a lot for the fast reply. My truck has had the check engine light on for some time now, and the mechanic said it was a intake leak. I was also getting like 0 mpg. Well I read about the problems a dirty MAF causes and decided to clean it, and the throttle body while I was there because its so easy to do. Popped off the MAF, it was spotless. I couldn't believe it, 193,000 miles and it looked like new. Sprayed it with cleaner anyway, and found the other sensor. When I popped it off, it was like a flat orange tab. One side was dirty, one was fairly clean. Figured MAF cleaner wouldn't hurt it and sprayed it clean. Cleaned the throttle body (really really bad) and then disconnected the battery. When I restarted it the check engine light wasn't on and it hasn't come on yet (10 miles). I soon going for a 150 mile drive back to school, and I can see if the light comes back and check the mileage.

 

[adsm08]

I doubt you'd have gotten through a drive cycle in 10 miles of regular driving.

Get out on the highway (at night will probably be easier) and then get up to at least 65, then let off the gas and coast down to 35. Don't touch the brake, don't touch the gas, don't touch the clutch, until you get down to 35. Then run back up the 65. Do that 3 times, and you should have gotten through most of a drive cycle. Enough to start setting O2, misfire, and fuel system monitors. That will let you know if you still have your lean-running problem (which you probably do).

 

[Nathan123]

Well, about 10 more miles at 60mph the light came back on. Stopped at the advance auto on the way back to school and the scanner said malfunctioning O2 sensor, bank one, downstream. I thought there was only 1 after the cat because the truck doesn't have duals? That was the only code, and according to the gas gauge, the mileage improved, we'll see though when I get the numbers. I plan to test the O2 sensor (if I can get it out) and unfortunately I think I'm gonna have to drop 65 bucks for a new one. A bad O2 sensor shouldn't affect mileage though, it just wont pass emissions?

 

[ozziemo27]

Is that an engine swapped vehicle? SOHCs didn't come in rangers in 1999.

 

[adsm08]

You should only have one downstream O2. If it's going it won't affect mileage. The upstreams are there to fine tune air fuel ratio. The downstream is to monitor catalyst efficiency. Your cats are one piece with the y-pipe. You only need 1 downstream sensor because if one cat goes bad you gotta replace them both anyway.

 

[Nathan123]

In 1998 the 4.0L SOHC (Single Over Head Cam) engine replaced the 4.0L OHV engine producing 207hp. I copied that straight from the tech library under engines, 4.0. This isn't my truck, it's my dad's and I don't know everything about it (I have a bronco ii, 2.9). As I double checked myself and went to copy that line, I looked in the chart on that page and it says that the OHV was 90'-2000. The SOHC was 2001-2007. I think this might be a technical error? Thanks for the info adsm. Why does advance sell a plain looking sensor (NGK, no wires) and one with wires (the bosch one)?