Here's the short history of my 1996 F150 with 4.9 Y.

I bought the truck last fall for the purpose of towing a boat and general hauling. Here in the state of Illinois you have to pass emissions in order to renew your license plate.

The truck has made a slight puffing sound when you get on it. A mechanic friend of mine seems to think it is a stuck air pump diverter or check valve since we can't seem to find any exhaust leaks underneath.

Aside from that there are 4 OBDII codes;

P0113 IAT circuit high input. I can't find an IAT sensor online at Oreilly, Advance, or AutoZone. They all have an ACT (Air Charge Temp) sensor which looks like the picture I found of an IAT sensor online. The sensor on the vehicle is mounted to the air filter box on the side before the filter. As far as I have found online I should get resistance of 37.3 to 24.3 ohms across the coil at ambient temperatures from 68 to 86 farenheit respectively. If not then I beleive that would mean the sensor needs to be replaced.

P0136 and P0141 Downstream HO2S Circuit and Heater Circuit fault bank 1. Since both sensor and heater circuits show faults AND my OBDII reader shows only 0.005v I am thinking that the sensor may be bad. I will get under the truck and check the heater circuit first, if it is OC then I know the sensor is bad. Otherwise is there a resistance value I should be looking for on the sensor side?

P1409 EGR Vacuum regulator Circuit Malfunction. One site suggested that the coil of the EGR vac regulator should be between 20 and 70 ohms. That seems like a pretty wide range. Does anyone know if there is a narrower range to be looking for?

I don't have a stack of greenbacks to hand a shop and the last thing I want to do is start throwing parts at a problem to hopefully fix it. I am a copier tech and we call that shotgunning. I know a lot of techs that do it but the error codes don't always point to the CAUSE of a problem, only the result of the faulty components. It usually leads to wasted money and machines that are still broken.

So the main question is are the IAT and ACT sensor the same item?

Is there anything I am missing aside from the plan I have for diagnosis?

 

Should be the same part:
MOTORCRAFT Part # DY720 Alternate/OEM Part Number(s): {#E4AF12A697BA, F5AF12A697AA, F5AZ12A697A}
F5AF-12A697-AA

AIRTEX / WELLS Part # 5S1038
STANDARD MOTOR PRODUCTS Part # AX25

 

Thanks, Subford, that's what I was hoping for. Time to get the ohmeter out and go gremlin hunting.

 

Yes IAT and ACT are two different names for the same thing. Definitely looks like your downstream O2 is bad as well, this won't affect engine operation but if you need the codes to be "all clear" for emissions tests then you have no choice but replace it. Also check that you are getting 12v at the EVR connector before replacing the solenoid.

 

Adamjr,
There are quite a few repair shops that could take lessons from you on how to troubleshoot. I've seen a lot of places that have the "throw money at it until it's fixed" mentality. Good job.

 

Thanks for the compliment. It's always easy to throw someone elses money at a problem. Look at the government of any nation.

When it comes to work I look at machines under contract as giving me an unchained ability to fix a problem. But I'd rather spend 3 hours of the company's time replacing a $4.00 photo-interruptor (2 3/4 hours diagnosis time) then 2 service calls and a few grand in parts. More people in my situation need to look at the company cash as their cash in terms of 401K contributions etc. But I digress.

 

Thanks for the additional verification. I found a site with some pretty good info on the EVR as well as other sensors. I am pretty sure I found it through someon's link on tis site while I was beginning my research. Ford Fuel Injection EGR Vacuum Regulator (EVR)

It looks like if I'm lucky and it turns out to be the two sensors and the EVR I could fix it all for under a hundred bucks. I could be really lucky and have the EVR code problem due to a bad vacuum line, wouldn't that be nice.