Hopefully I can get some advice as to what to look for, or pointers from those of you who have had or seen similar problems.

Vehicle: 2004 Ford F-150 Heritage (97 - 03 body style)
Specs: 4.6L Triton V8, 4x4, automatic


Story: Up until last Wednesday my truck was running like a top. Even during the day on Wednesday it was running great. I drove home from work, pulled in and put it in park. I noticed that the idle was low, and the the "Service engine soon" light came on. I sat there and let it idle for a little bit, and it was not idling great at all. It was fluctuating between 500rpm and 900rpm, and shaking a little bit. I ran the test on the light, and the stored code was P2195 (O2 Sensor Stuck Lean (Bank1 Sensor1)), and pending code P2197 (O2 Sensor Stuck Lean (Bank2 Sensor1)).

That leads me to believe I am actually running lean, and it is not a bad o2 sensor since both of them are throwing a code, and I think I would have a better chance winning the lottery than both sensor's going out at the same time, but then again I could be way off base. The truck runs fine at higher RPM's when I am giving it gas, so I would think my fuel pump is putting out enough pressure, especially to keep up with the idle.

That being said, with all of the sensors and stuff not being the cheapest of fixes I want to try and pinpoint the problem before spending lots of money on unnecessary parts and labor. I replaced the fuel filter, and put a bottle of fuel injector cleaner in the tank and used mid-grade gas instead of low grade. I have only ran maybe 15 miles on the fillup and filter (tank had 1/4 left in it when I filled up). As of right now, I am still having the same problems and was going to run this tank through and see if I seen any improvements.

I also bought a new PCV valve since it was like $3.00 and I needed to get to $20.00 at AZ for my credit on my rewards card anyways, but could not find it. The Haynes manual said it was on the passenger side valve cover, but it was not. There was a hose coming out of each of the valve covers, but no PCV, so I assume my truck is a funky one in some other location that I will need to track down when I get time next.

I tried testing the Idle Air control valve, and the TPS, but I could not even get a good reading off the TPS from "backprobing" according to the Haynes manual.

What would you suggest I try next? I was thinking do the plugs, and note if any of them look different from the others and go from there.


Any help is greatly appreciated.

Joe

 

Your going in the right direction.
How about looking for an air leak at a hose or hardware at some point on the intake system? That will make things lean for sure because it's un measured air after the air meter.
To test the IAC in a practical way, with the engine at idle hopefuuly at 600 or above, remove the connector.
If the rpm goes low you know it was working because it's an air bypass that closed off air to the motor.
You can test for a leaking EGR system by removing the EGR hose.
If the engine smooths out, the EGR was allowing exhaust gas back into the intake when it should be closed.
Good luck.

 

I think the PCV valve may be behind the throttle body on your truck.
You can google it (pics of PCV on Ford 4.6 truck) and get some pictures.

A vacuum leak will case a lean code!

 

Thanks for your response.

I will check the entire air intake system tonight. You are saying that every connection needs to be checked between the MAF sensor and the Throttle body, correct?

As far as the IAC goes, my idle is pretty erratic, but I think I should be able to notice a difference in the idle regardless of it being erratic. That is also an easy enough check.

For the EGR, when you say remove the EGR hose, are you referring to the line that comes in from the exhaust system, or just simply pull the vacuum line? I would guess the main line coming if from the exhaust, just wanted to clarify.


I will check all of these tonight and post back. Thanks again, keep em coming.

 

That is kinda what I was thinking after researching it a little bit.... I guess it draws from both valve covers and meets in one location to flow through the PCV.

I really hope not on the vacuum leak..... That is one thing I have never had to mess with. I am just now becoming a little more comfortable with electrical problems and reading a multi-meter.

Is there any specific lines that you would check for a vacuum leak that would cause it to be lean, or is that something that I am going to have to trace every vacuum line and go from there?


Thanks for the reply.

 

The hose to the EGR not the metal tube.
If the EVR is allowing vacuum to the EGR, it will result in rough running.
A non sealing EGR it'self will do the same thing.
Good luck.

 

Pulled the harness for the IAC, and the RPM's dropped so I assume that is not my problem.

I will pull the vacuum line on the EGR on my lunch break and see if that smooths the idle out. I will check the intake tonight and see if I can't find any leaks in it.

 

Pulled the vacuum on the EGR valve, and nothing changed as far as the crappy idle. I am hoping to get time in the next couple days to pull everything off in front of the throttle body and inspect for leaks.

 

Okay fellas... Been busy as crap at work, and been putting this to the side. Got some free time and looked into it a little more. Anyways there is a hissing under the hood, and it wasn't a snake. There is a vacuum leak coming from the joint behind the throttle body. I started the truck and my buddy sprayed WD40 all over it with a steady stream and the idle smoothed out. It isn't a hose, it is somewhere on the plastic joint.

I didn't have the time to pull the throttle body yet. This is a different setup than the standard 4.6 motor because there is a water line going into the thing too. Anybody know how hard it is to get this plastic joint piece out, or even know what kinda part number to look up? I am thinking of pulling the whole throttle body and just using some JB weld on the darn thing.

 

Just an update....

The back elbow piece on the PCV tube was completely collapsed in, after wrestling around trying to get the remaining pieces off, I finally got it to come off. It was a bear to get off. Finally I get it off, and go to multiple auto parts stores, and nobody carries it, a few of them even said that it was not in their system, other say it is special order. I just bought some heater hose, and routed it a little bit longer of a way around so it would not kink up around the tight bends. Fired her up and she runs fine now.

Do you think the heater hose will be good enough to use, or should I go ahead and order the factory replacement hose with the two elbows?

 

The piece of heater hose should work just fine as long as it doesn't collapse or kink.
Might not be a bad idea to order the factory elbow just to have on hand in case of a problem though.