Hello whoever's willing to listen. I appreciate your interest. I bought an 02 E250 for my work as a flooring contractor. It ran rough so I changed all the plugs and the coils on the two cylinders the trouble codes indicated, 4 and 7. This was in addition to changing the air, fuel, oil and transmission filters and the PCV valve as well as cleaning the throttle body and MAF sensor. This did not solve the problem. I checked all the connectors for the coils and injectors with a noid light and they all worked. It turned out to be the injectors on cylinders 4 and 7. I replaced them and all was well...for a few days. Then I started getting a misfire on cylinder 2. It turned out that the coil had broken off from the hold down bolt and was damaged from slapping around. I checked the coils I had removed previously with a multimeter and got the correct resistance. Swapped that in and it ran fine. The next day there was a misfire on the same cylinder. That turned out to be a damaged connector coming loose. I wired in a new one and it ran fine again. A few days later I noticed a lack of power and had some codes pop up. P0171 and P0174. I bought a scan tool with live data to investigate. The ltft was very high on both banks. Following the recommendation of a website I checked physically for vacuum leaks and torn hoses, especially where the PCV tube goes in to the back of the intake. Nothing. I tested the o2 sensors by locating a vacuum line and spraying throttle cleaner into it. The pre-cat o2 sensors jumped to 0.9v and took a second to clear which, according to what I was reading, means that they work. I tried spraying cleaner around the intake and vacuum connections and got no response from rpm or o2 voltage. Today it worked pretty well at first but then it started dying going up hills on the highway. Then it started misfiring on various cylinders. P0300, P0304, P0307 and P0308. I cleared the codes and some of those came back, some did not. I managed to limp home at 35 on the back roads while praying that I could make it up the slightest slope. Never stopped or stalled out though. It would work if I slowly rolled on the throttle, barely cracking it. If I gave it too much it jerked and wouldn't increase rpm. I feel if I had stepped on it would have stalled. I did have a code about low coolant temperature a day with the scanner found that the ECT reads in the high 160's to low 170's, which seems very low. I plan on checking fuel pressure as well as making sure that the misfires aren't a separate issue. As two of the affected cylinders have new coils, injectors and plugs I don't think that's likely but I'll check anyway. I also have read that clogged cats or an exhaust leak could cause these symptoms. Does anyone have an idea how I could go about testing those items? Any thoughts on the likely culprit that I should test first? Anything that I'm missing? PCM reflash? A fuel module under the van that I've heard tell of? If you need any data that my tool can provide it's yours for the asking. I appreciate any help, ideas or information that you may have and I'd be very grateful if, after reading this overly long post, you could provide me with some insight before my hindsight starts telling me I shouldn't have bought it, lol. Thanks for taking the time to read this and thanks in advance to those who contribute.

 

Definitely check the fuel pressure next.
Not sure what the pressure should be for a 2002, our 2003 Exped reads 52 psi. Our 2002 V10 Excursion is 34 psi. Should at least be 30 psi. The fuel pump relay may be going bad. Burnt relay contacts could be limiting the voltage/current getting to the pump. You can measure the volts at the inertia switch, from there it's just a wire to the pump.
Also, what is the manifold vacuum at idle? I think mine is 19.
I had clogged cats from a long run of misfiring on our Exped (long story), but yours doesn't seem the same symptoms. The engine would rev fine when not in gear. It would get up to 65 mph if accelerated real slow, would not accelerate fast at all and had no power going up hills. At first it would only do 65 up a steep hill near us when I knew it would do 75, no problem. Then it would only do 60, then 55. I had corrected the misfiring, but the damage had been done. Ran fine, otherwise. I had found a vacuum test to run which confirmed a clogged exhaust, but can't remember the specifics. I see there is now a pressure gauge available that screws into a standard O2 port to directly measure exhaust back pressure.

 

Thanks for the suggestions. I checked the future pressure and it gets up to 35 psi with the key on, engine off. It seems to bleed down from that pretty soon after hitting it but the bled down itself is slow, stopping at around 20. While idling it gets up to 55 psi with the needle twitching the whole time. I don't see any fuel leaks and two of the cylinders that have misfires have new injectors so I doubt they both leak out of the box. Plenty of pressure at idle, maybe too much. I'm thinking fuel pressure regulator. I'm about to review how to test that and I'll let you know the results.

 

I forgot to mention that it bleeds down after the engine is cut off, even with the key only going back to start. No change in psi from opening the throttle or from removing the vacuum line from the fuel pressure regulator.

 

After idling for five minutes or so pressure holds around 30psi with the needle quivering rapidly. Hitting the gas makes it jump to 40psi. Then mid 20's before returning to around 30. Still no response from pulling the FPR vacuum line. After shutting off the engine it bleeds down to 10psi within a minute and holds there as long as I've been checking. Clearly something is up with the fuel system. I think I'm going to replace the FPR and see what happens.

 

With the purchase of a set of snap ring pliers I was able to remove and replace the FPR. It's idling better and the fuel pressure no longer bleeds down. pressure at the rail while running got up to 70psi but I haven't given it time to warm up. Live data on the scan tool shows the long term fuel trim is right for the first time. Hopefully that's it. Time for a good long test drive including the interstate to see if all is well or is the misfires were a separate issue. They better not be, lol. I spent enough time chasing those before this cropped up. I'll report back in a bit.

 

Not the problem. I won't take the FPR back because it did seem to correct some pressure issues but I'm getting p0171, p0174, p0304, p0307 and p0308. It started out fine but within ten minutes it was dying uphill and I limped home slowly. Maybe it is the fuel pump. Could it work fine cold and then quickly degrade under load? I don't see why the cats would clog up as it warmed up and they don't seem excessively hot. I've checked everything that I can think of. If anyone has any advice I'd greatly appreciate it. I'll be searching the forums, spraying cleaner at possible leaks and trying the fuel pressure under load in the meantime.

 

Would a fuel injector stuck open cause any of your problems?
I recently checked the fuel pressure on our 2003 5.4L Exped 152K and it was 52 psi at idle. After sitting for a day the pressure dropped to 40 psi. After another day it dropped to 30 psi and after the 3rd day it was 20 psi. I was working on the coolant lines rerouting things to get better access to the COPs and waiting for the fuel pressure to drop so I could take off the gauge. It didn't get below 10 psi so I just took it off with paper towels around the fitting.
Also, I think once the cats are clogged, they are clogged, probably because the honeycomb broke into pieces. I've had 2 that broke up for sure. I didn't open the ones from our Exped to see.

 

Sorry it took so long to get back to this but I've been busy. I eventually took it to a shop. They tried replacing the cats with no effect. Once they got in to it they found damaged chain guides, a jumped timing chain and bent valves. Repairing that sounded extremely expensive for a 14 year old work truck so it has been sold. I always heard that an OHC engine destroys itself if the timing jumps so I never thought of it. Just goes to show that you should try to find specific knowledge rather than relying on the common variety. Thanks to all for your suggestions. This might be heresy on this site but I'm considering a Chevy Express for my next van. Perhaps a pre mod motor Ford. From everything I hear the 5.4 is a good engine out of the box but can't handle mistreatment. Unfortunately in my price range mistreatment is all too common. I've never owned a Dodge other than a Neon. So any opinions on the best brand of low budget used V8 cargo vans?

 

Not just OHC engines. I had a 351W in a '69 Mach 1 hop the timing chain and it bent all the exhaust valves. Ford used aluminum timing gears with nylon coated teeth to keep it quiet. After replacing the gear with a cast iron gear I never heard any timing gear whine. Ford's bean counters seem more concerned about saving a few bucks than having a reputation for making good products - like not using plastic in timing components or installing spark plug inserts in aluminum heads or SS exhaust manifold studs or ... These upgrades could be done very inexpensively on the assembly line compared to what people have to deal with later on.