99 ford E 150, 210,00 miles throwing codes.........bank 1 & bank 2 lean, misfire cyl 3.........I've replaced almost everything. Any suggestions.......

 

I might be wrong, but I seem to remember a vacuum leak is a common cause for both bank 1 and bank 2 lean codes occuring at the same time.

Misfire on #3?
Sounds like it might not be related. Have you replaced plugs and wires?
Also, the module where the plug wires attach can go bad and cause misfire codes.

 

Yeppers, the leak was at the rubber elbow front of engine kinda under the plenum at the tube. Runs much better, except code for cyl 3, I will troubleshoot today. Thank You, Thank You !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I am having the same problem with my 2003 F-150 4.2 V6. I found a service bulleting that makes sense. If it only happens in cold weather is is caused by the plastic intake manifold warping and causing a vaccuum leak but first check all your vaccuum hoses to make sure they are not cracked. Also make sure you use the correct Motorcraft EGR valve for the engine because they are calibrated for the computer.
The simptoms on my truck are a non steady idle that fluctuates in RPM but it only happens in cold weather. Resetting the trouble light makes it go away for a couple of weeks and comes back in the next cold spell. I live in Florida.
I replaced the air temperature probe and the MAF but it was just a waste of money

 

I spoke too sooooooooooooooon..............now I am getting a mifire code cyl 3 & 5 ??????????

 

Well the lean code appears to have been solved with the vacuum leak getting corrected.
So now it is just misfire, correct?

I'd be suspicious of the coil pack, or maybe plugs/wires if they have not been changed.
I can not remember for certain, but I think the cam position sensor has been know to cause this problemas well. Start with the obvious/most likely and go on from there.

Try using the "search" function and see if you find somethign helpful.
Lots of stuff built up here over the years.

 

Replaced the plugs, wires and coil ................I disconnected the battery to reset, CEL is off for now, but I still feel a slight miss.......I know the light will come back on....it always does

 

This is what I did this weekend..............3 cyl compression test......@150 not bad I think. Put original coil back in, changed #3 plug.....didn't look bad at all and switched the wire from 2 to 3 to see if the wire was bad. Now at around 30mph you can feel it start bucking just like theres a miss, CEL not on yet but I am waiting.
Maybe a fuel injector...........gesh I dont know ?????????

 

Try checking the idle air control clips. These clips are hard to find. Use an inspection mirror and look in back behind the intake, there are 4 small white round plastic clips that connect the iac rods from the iac to the intake, I have found them broken many times and they will kick out a missfire code.

 

In all my experiences working on the 4.2 motor it has a track record for clogging up the egr runners in the lower intake. I've seen on more than 3 occasions were the ports were clogged on all cylinders but 1 or 2. So when the egr was commanded to the engine instead of going to all 6 cylinders like it should it only went to the one(s) that were not clogged up yet and that makes a misfire that can be difficult to track if you haven't seen this problem before.

This could still be a coil pack issue (seen this as a problem as well) but with 210K on the clock I'd be suspecting the egr ports are clogged. You can take the upper intake off and on the lower intake you'll see circular ports that are in the intake runners (drawing this all from memory so I might be off on the location some) but chances are when you find them they'll all be stopped up except for a couple. I've taken a small drill bit and just used that to clean the ports and then put the upper intake back on using the new/revised intake gaskets as well.

Just something to ponder on if your still running into this problem in the next few days.

 

^---What he said. Apply vacuum to the EGR valve with the engine idling and I bet you a 6-pack it will start skipping. I would blow out all the ports with compressed air(watch out for the soot!) instead of just poking out the carbon. FYI, the clips TK are referring to are for the IMRC and won't cause a misfire.