95 4.9 inline 6 f150. It's got that retarded obd1 nonsense. The check engine light has been on since I got it. I counted the blinky lights, got a code 31, which is something to do with the EGR/EVP circuit. I replaced the physically broken charge air temperature sensor, took it for a road test. The engine light is not illuminated at this time? Possible that faulty IAT circuit caused false readings from EGR circuit? Anyone know anything about this system?

 

Don't be so quick to judge, it's a basic EFI system that is usually very reliable once you get the bugs worked out.. which often are not directly related to the EFI system but to the more basic engine stuff.

Not likely. Two possibilities here.. you counted the blinky lights wrong.. that's not a poke at you it makes me go cross eyed sometimes too so always suggest investing in a basic(cheap) code reader like the Equus 3145. Other possibility is you counted right and that problem still exists but it's not as major as the broken ACT sensor so the light goes off. Suggest clearing codes by disconnecting the battery for 15 min and then drive it for a few days and check the codes again to see what came back. If you still get EGR codes post them up, but in the mean time look for cracked or broken vacuum lines on the motor.. that is as much of a problem on an old truck as anything.

 

I'm sure it's a fairly reliable system, if you take the time to figure out how it all works. I'm also pretty sure that I counted the flashes wrong. I think there was an 11 then a 31 then a 13. I'm going to buy the code reader if the light comes back on.

I work at a German car dealership, with all these fancy new modules and scan tools and I'm a little spoiled by the amount of information available on our cars. That and the fact that every sensor and control module has a different name makes working on my truck a little confusing for me. So, I don't feel offended when you tell me I might be wrong, because I accept that I have a lot to learn.

All that aside, when I bought the truck last February, it had a dead battery and after we jumped it the light came on right away. I let it sit till last month, when I started driving it every day. I replaced the battery last month (it was totally dead) and the light came on as soon as I started it. It's been on constantly since then, until I replaced the charge air temp sensor today. I only took it for a ten minute spin, so maybe it's just a coincidence. I was thinking (without any knowledge of the system) that maybe it's possible that the PCM is reading the IAT values (open circuit) and determining that the engine is too cold to operate the EGR, which is then creating the fault code. Then again, maybe not.

Oh, and the truck's been averaging 11mpg. I'm hoping that after replacing the temp sensor and changing plugs, cap and rotor it'll get closer to 15. Is this realistic? The truck has 210,000 on it and as far as I know has never had any kind of rebuild. What kind of mileage does everyone else get?

 

The I6 trucks are capable of 20+ mpg highway and high teens city but much depends upon overall gearing and how it's driven, short hops of a couple miles that don't even let the motor reach closed loop will produce abysmal numbers but 15 minute runs at moderate speeds can net impressive milage. Check the axle code on the drivers door pillar and compare to the chart here.. Ford Axle Code Chart .: Articles

 

Pretty sure the previous owner swapped out the axle at some point. Not sure if he kept the same gearing. I can get a pretty rough estimate by lifting the truck, spinning the driveshaft and counting the amount of times the rear wheels spin, right?

 

A 1995 truck should display three digit codes.

 

On a 1995 the code you were reading was 113 and then another 113.
The code will repeat twice.

And a 113 (IAT) indicates the sensor signal is greater than the Self-Test maximum. The maximum for IAT sensors is 4.6 volts.

 

Well, that makes a lot more sense. Glad I asked . I thought it was code 11 for system test beginning, code 31 for egr, then whatever 13 is. But thanks for making that a little more clear for me.