I have a 1994 F350 Econoline R.V. with 460 motor, 69k miles. I just bought van and trying to sort out some issues. It has a miss that is inconsistent. I put in new plugs, plug wires, (wires and firing order are correct) distributor cap and rotor. The plugs I pulled out were clean, no oil showing and gap were good. It seems to run a bit smoother but still misses and backfired a couple times. After running engine for about half an hour, it hasn't backfired again, but once, it almost died but recovered and remained running. I have looked for vacuum leaks and found none. I will change fuel filter under cab, but it has push lock connectors on fuel line, so I have to buy the tools to disconnect them I'm also wondering if the miss is related to the smog system, and boy, this motor has a lot of smog stuff! Any help is greatly appreciated.

 

Probably ought to check the codes and the fuel pressure
I would take a fuel sample too, and do a fuel volume test for GP's
Probably ought to check the capacitors in your processor
The coil center terminal, (high tension terminal) did you check that? They corrode sometimes
If the TFI and stator are original, I'd replace them both as well

 

Thank you for the input! This RV has been sitting a lot over its life (31 years old and 69K miles) but seems to have been well cared for. I will check the coil terminus connection for corrosion. I'm not sure what or where the TFI and stator are located, if you would explain that would be much appreciated. Update; since it has been sitting awhile, I put a can of Sea Foam into tank, and it is running somewhat smoother but is still missing some. I have a new fuel filter to change out (never saw a quick disconnect on a fuel line to filter!). I have noticed there is a lot of noise that seems to be coming from the smog system, you can hear it as a roar that changes almost like a valve opening cycling on and off from tail pipe. Also, the cat has been removed and the small (1" diameter) pipe has been welded shut. Once again, thank you!

 

94 E series, your TFI module should be by the drivers side hood hinge
Stator is inside the distributor
Thermactor (air pump) will "fart" air out the bypass valve when cold and no air is needed at the converter or heads
The TAB and TAD solenoids control the thermactor air
Sounds like that is working correctly if it farts air once in a while

 

Thank you for your reply. I will check the TFI and stator tomorrow. I checked the fuel and installed new fuel filter, also added fresh fuel to tank. So far, haven't found anything else not working properly, but wonder if miss might be from fuel injectors, and if so, how would I test them?

 

I monitor the fuel pressure while I fire each injector manually with a trunk switch
That is what our old SBDS machine did at the dealer back in the day
It's quite a bit of work to do that testing (fab up a harness with an injector plug and some test leads and a switch)
Round about then in the testing I would be checking the caps in the processor and looking at the injector drivers
Noid test light installed for testing the processor signal

 

Update; on engine miss. Still trying to sort this engine miss out. The one thing that has helped to improve engine running smoother besides tune up stuff is adding Sea Foam to gas tank and to motor oil. I believe that is due to vehicle sitting a lot before I got it. I emptied the gas tank, changed fuel filter, added Sea Foam to fresh gas, and am on second tank of gas. Overall, engine is running smoother yet, still misses intermittently and at times stumbles like if you turned key off and quickly back on as to almost die but never does. I have checked coil, found no vacuum leaks as of yet. I have an OBD-1 code reader and after running all tests, only two codes showed up, 173 - HEGO-HO2S, right side rich and 538 - insufficient RPM change during KOER Dyn response or, invalid cylinder balance due to throttle movement during test. Still looking for the culprit. One thing I've noted is when engine is first started and for about 10 seconds it runs smooth as can be, then roughness starts. Trouble here in Anchorage is, none of the repair shops want to work on a 31-year-old RV. While I can work on some systems on a motor, I don't have all the skills. Thank you all for any suggestions..

 

After a lot of diagnosis on this E-350, I pulled the PCM, opened it and found a burnt capacitor. Using the OBD-1 reader, I found the timing was off and the only option was to repair or replace the PCM. I sent it out for repairs and am anxiously waiting for it to return. This PCM issue seems to be a weak link in an otherwise great E-350 van and, replacements are very hard to find and not cheap. I am looking to find a backup PCM just in case! I am also aware that until I reinstall mine when repaired, There might still be other issues to contend with. Whew! If anyone has any info on where I might find a replacement please let me know. I was wondering if any aftermarket suppliers have a replacement model, similar to a tuner? Thank you for the help.

 

I found a Cardone reman processor for mine on Ebay

 

Just a few thoughts here:
If you do an Ohm check on the TPS if any hickups in the sweep from closed to fully open throttle plates could cause issues.

Another thought here is your Air-flow sensor. My Subaru WRX has similar issues as you are having and my mechanic said the Airflow Sensor was the Culprit. I had loaned the car to my daughter after I attempted cleaning the sensor, so could have been my fauilt, who knows.

I drive on occasion, my '78 Ford E250 Chateau wagon with 460 and love the engine.
My only complain is power steering pump Belt-Squeal with the narrow "V" belt.
My crank pulleys are slightly out of round, which probably compromises the belt tension. Therefore, I'm considering pulling the pulleys, laying them on my anvil and gently tapping the area around the bolt holes, then adding grade 8 flat washers to help hold the pulleys to the balancer for less deflection. _ _ gotta love the 460

 

Update on rough running 1994 E350 with 460 motor. I finally got around to installing my rebuilt PCM from my 1994 E-350 motor home. I recently bought this motor home, and it had a few issues to figure out, but overall a great vehicle with low mileage (70,000 miles) The biggest issue was rough running engine. I spent many hours troubleshooting this and after checking for issues with anything and everything that could cause rough running, the OBD-1 code reader indicated a faulty PCM. This fault was found while testing for PCM to alter timing while in test mode. Long story short, only option was to replace or rebuild PCM, which I found no new units available so sent mine to be repaired if at all possible. Was hoping rebuilt PCM would fix all issues but not garranteed. Well, after install of PCM, the engine runs perfectly smooth with no issues! Have to say , that was a big relief as, there is always a chance that while troubleshooting I might cause another issue. So now, I am looking to find a way to get better fuel mileage(9 to 10 mpg on a good day). I'm looking for a performance chip system to help get better mpg's. Other than that, want to say thank you to all those that gave input on this forum, as Your input helped me down the path to where I'm at now, which is able to use RV and enjoy. Thank you all!

 

Thanks for letting us know what fixed it!

9-10MPG is pretty good for that, unless you're talking a factory-body standard van where you miiiiight get maybe 11. I'd leave it be and just catch up on all the maintenance.