Greetings, I have an E150 4.2l 2001 that has given me a few problems. It just died and with the help of the internet I determined that the pcm went out. It now runs after replacing with used pcm but immediately threw a P1151 code heated oxygen sensor bank 2 sensor 1 switch point indicates lean. I have never had that code but have 200k miles on van. Any help would be appreciated.

 

Well, this is a classic case of running lean, bank 2. Which means, specifically, that the PCM couldn't drive the fuel rich enough to get it to switch, and it was still stuck lean.
With this powertrain, the freeze frame data would be useful; if it happend when hot and driving for a while, I would look to the fuel delievery system (fuel pump) that might be weak. Also, a misfire in bank 2 would cause this in an extreme case (but would usually set a P030X).
If you can monitor PID's, then look at 02S21, and spray some carb cleaner into the intake (the pcv tube hole works well for this), and see if it comes to life. If it does, then there's either a air leak in bank 2 (drivers side), or if looking at freeze frame data, if bank 1 is running anywhere over 10% rich, there is a global (whole engine) problem that just hasn't cropped up on bank 1, yet. Look for the rubber connecotrs rotting out, and possibly the mass airflow sensor. Let us know.

 

Thank you for your response. I believe that the fuel system is ok, for now, but one thing that I forgot to mention that relates to your response is a slight poping coming from the front of the engine. This began after I cleaned the MAS with seafoam spray. I understand it is supposed to be sensor safe but I may have damaged it or it wasn't working properly when I cleaned it. [I have since bought sensor cleaner.] I have ordered a new MAS and will update next week when I get back in town but I have one more question- Is it normal for the 2nd wire goinging into the coil pack, that pulses the #2&#6 cylinders, to have a constant ground when the engine and ignition is off and pluged in to the coil? I checked it unpluged and no ground, and I checked the wire with ohm meter for ground and found it ok. That was the origonal reason for replacing the pcm was that the 2nd wire was grounded while unpluged from coil and not pulsing. Thanks to all who read.

 

Well, if I get what you're telling me correctly (and I may be wrong), there's a blue/green or red with something wire that goes back to the PCM for the ground. If you checked the continuity and it's ok with the PCM disconnected, I would check to make sure that the spark is occuring at the end of the plug wire when running (watch out you don't get shocked). That's the easiest way to tell what's going on; the wires could be getting a ground through the PCM when off, and the only way to tell is to disconnect the PCM and battery to make sure there is no power in the system. If you have spark good. But, it was a common problem for these engines to short out at the plug wire connector in the coil pack, leaving one clyinder misfiring, then over time to take out the PCM driver. I've seen this before, so watch out. It's really easy to misdiagnose this, as it's sometimes hard to believe that the dual-fire approach would fire correctly on one side of the coil pack, but not the other. It's hard to believe, but I've seen it more then once on this powertrain.

 

Here is the updated history of my problem. After changing the pcm with a used one the enging fired. OBD sent P1151.I replaced the MAF sensor and that is now gone. Engine still runs rough. I replaced the coil with OEM. Engine starts well and idles well but not much power. I reset codes and now have new codes- P0171 sys too lean bank 1 and P0174 sys too lean bank 2, P0302 misfire cylinder 2 and P0306 misfire cylinder 6. I have checked for vacume with carb cleaner and didn't find anything but that dosn't mean there isn't one. Where do I look now. Thank you for your response. :]

 

Well, this is going to be a pain. But, at this point, with miles on the car, I'd probably start with a base compression test to make sure the engine CAN run well. However, the misfires are both in companion clyinders, which fire at the same time (2 and 6). So, go back to the wiring problem, and make triple darned sure that the wire that goes from the coil to the pcm has no opens, and no shorts to power or ground.
I know I'm probably covering some 'already been looked at stuff'; but, make sure the wires and plugs are OK too.
I wouldn't go too far with the ancilliary codes of P0171, P0174 until the misfire is fixed, as the misfires will set these codes. However, the misfires could be caused by a huge vacuum leak. These had a PCV tube that run from under the throttle body to the PCV valve in the rt. valve cover, so check underneath the throttle body to make sure the rubber elbow isn't totally rotted out (which was really, really common). Check the PCV connection also.
I'm also assuming the misfire is at idle; if it's not, then most likely the EGR ports are clogged up in those clyinders (which would show itself as a miss on accel.) If the ports are clogged, a really easy way to check for this is to disconnect and plug the vac. line going into the EGR valve and road test. If the miss is gone, you know that the ports are clogged (though it was usually clys. 3 and 6 that this happened in, I've seen them all over). Please let us know!

 

WOW what a battle! After a lot of reading and thinking I started doing the simple things. I checked spark at the coil and at the plug and all had a brilliant blue spark. I double checked the wire at the coil to the PCM. All ok. No vacuume leaks. Checked and cleaned the EGR valve. Works properly. I then remembered that I had once had to clean the tubes going to the DPFE and removed the pipe from exhaust to EGR valve. The tubes were almost entirely blocked. After a lot of carb cleaner and wire, the blockage was cleared. I still had a misfire on cyl. 2. Although I had recently changed all spark plugs, I removed #2 and replaced it with a plug that was good. OMG! The simple things make all the difference. As of now, I know it is still a bit early to celebrate, there are no codes and no pending codes and the van is running like a van with 201k miles. I continue to be impressed with the quality of product that Ford produces.(I own nothing but Ford vehicles.) One sure thing I take from this experience is to use only Ford parts when they apply to the engine operation. I thank you for your advice and support in this challange and will be a regular supporter of this forum.