I have a 2003 F150 with a 4.6. I have had the check engine light on for 10 months its been to 4 ford dealers and 2 independant shop run by former ford techs. When you scan it code 172 comes up which is rich on right side. No one has a clue what to do to we have moved all the sensors, injectors and ego's from side to side no change I dont want to start throwing parts at it and hope it stays off. If you clear the code the light may stay off for 10 miles or 200 miles. Ive spent over 800 bucks on it so far. I wanna get rid of it but its it hard to sell with the service engine light on. Any Ideas?

 

Look for an intake manifold leak on that bank. Good luck!

 

I took it to another guy today and he says its a intake leak, so we will try that repair to see if it helps

 

Well I listened to all the pros on Ford Trucks and replaced the intake gaskets and service engine is back on and still has code PO172. Cant sell it to anyone with the light and its been for sale for a year. The local ford dealer cant sell it and with no more $$$ to spend on trying to fix the problem $2000 so far I'll take it to the auction and dump it and take my loses.

 

Well you have to look at what the P0172 codes is(Bank 1 RICH). A vacuum leak will not set this codes(It will set a P0171 or P0174- Banks Lean). You have to look at how a rich condition can happen:
1) Bad MAF sensor(will generally set codes for both banks rich/lean though).
2) High Fuel pressure(check your running pressure at idle and WOT and make sure it's at spec.)
3) Incomplete combustion on effected bank(misfire- though you have no misfire codes).
4) Malfunctioning Oxygen sensor(Sensor sticking at above .5 volts indicating rich condition).
5) Leaking injector(though with this you will generally get a misfire as well).
6) Leaking Fuel pressure regulator(leaks fuel into the intake).

What you want to do is check your plugs and wires to ensure they are not old or damaged. Check fuel pressure(over pressure will cause more then desired fuel to be sprayed into the cylinder). If you have high pressure, check the fuel pressure regulator on the fuel rail for failure. Remove the vacuum hose from the regulator and check for fuel leaking. The diaphrams in these leak and let unmetered fuel leak into the intake. Possible Vapor Management valve sticking open for your Evap system could cause a rich condition as well.

The reason your CEL stays off, is it needs to run it's checks before it will set a code. The PCM runs a set # of drive cycles before it sets a code again.

 

This truck has been to the Ford Training Center also

 

(If I was the tech working on it) Well I would start by watching the STFT and LTFT and see where they're at(you want them between -10 and 10). I would inspect the fuel pressure regulator for leaks, then move onto a fuel pressure test(running at idle and WOT). You can also monitor fuel pressure after turning the engine off, and it should maintain a steady pressure. If the pressure starts to drop over time you could have a leaky injector. Access to an IDS gives you the "power balance test" where you can monitor misfires as well. You can also monitor O2 sensors for intermittant failures. If the sensor goes to about 1 volt and stays, you can always cause a vacuum leak and see if it leans out. If the O2 sensor stays rich even with your intentional vacuum leak, it could be a bad O2 sensor.

I was just telling you what most techs would do in this situation and some ideas to look for........

These are just common problems. There is also the possiblity of a bad module or bad wiring.

 

After showing all the test results from 2 ford dealers to another ford tech he said intake leak, then I told it had just been replaced. He got on the phone the Ford Hot line and they said try a PCM.( I do have access to one) Does anyone think that could be the problem? 3 very good Ford Techs have no clue and I cant afford to spend anymore $$

 

Did the tech take a look at the manifold for cracks in it?

 

Yes they have been cracked checked. This is a nice truck and I hate to dump it, but I cant sell it with the light on and cant afford to spend anymore $$. I found another truck with then same PCM so Im going to swap them and see what happens

 

What I don't understand is how an intake leak is causing a P0172(Bank 1 RICH). That should cause a "lean" code. Lean meaning more air then fuel, rich being more fuel then air. What is happening with an intake leak, is "unmetered" air is entering the intake system. Because it is entering after the MAF sensor the engine does not know where the air is coming from and therefore needs to bump injector pulse width up to compensate for the added air. This causes short term fuel trims to go high and sets a lean code. Are you sure you're not setting a lean code, but giving us a code for rich??? Lean codes are P0171 and P0174 I believe?

 

Also, I do not believe you can just swap PCM's on these trucks. You need to use an IDS to save module data before disconnecting the old and installing the new. After install you either need to upload the data previously saved, or force "As-Built" data into the module via the IDS. The pcm has a recognition code that it communicates with other modules, and if the codes from the other modules don't match the pcm it will not function. Don't hold me to this, but from the PCM's I have replaced, they all needed programming.

 

Im going to have a guy I work with install The PCM. the ID#S match. I do work at a Ford dealer, so the guy should know what to do (i hope) Hes been to all the schools. Ford Hot Line isnt much help.

 

Could the timing be off?

 

Timing is computer controlled. Not likely..... Unless you've had major engine work, I would guess problably not. When the codes are scanned, are there any misfire codes or other codes besides the P0172?