800 miles from home, no garage, 25-35*F ambient. From earlier on this trip, cruise struggles to keep speed uphill. Blip off and on the overdrive and it keeps going. Later on the trip there's a misfire in overdrive as the speed drops but blipping the overdrive button still keeps it going. Get to yesterday and I can feel the misfire at the higher rpm range in third gear. If this gets worse, I won't be able to keep a safe speed on the freeway. Feels to me like an ignition problem though the plugs, wires, rotor and cap are about 8K miles old. I suppose it could be a fuel problem but the misfires are quick blips rather than longer stumbles.

Next symptom. The weak cranking on warm restart is gone on its own but now it won't fire on the first cranking and catches quickly on the second. The first start of the day is quick. To restart, lean on the key for a 5 count, back to off, hit the key again and it starts.

To those who know the 5.8 well, does this sound like tune up parts or possibly a tired coil?

Sixto
93 E150 Chateau 5.8 193K miles

 

Cap and rotor look good - no burn traces and only mild pitting on the metal surfaces. 2 of the starboard plug wires were against the rusty crusty riser that feeds the cabin heaters. 1 was resting on a 1/2" pipe that ducks under the manifold. I rerouted the wires and will see if that helps.

Sixto
93 E150 Chateau 5.8 193K miles

 

sounds funny but drive at night with the cover off , Look and listen for sparks.

 

Quick diagnosis: plugged left cat.

Correct diagnosis, maybe maybe not. I don't know about the 93 emission control system, but if you have a downstream and upstream o2 sensor, pull the downstream sensors on both sides and go for a loud test drive up a big hill. It's easy (free) to do and will tell you if your cat is plugged. If the engine runs alright at lower RPM and only struggles under heavy load and high RPM then it's a strong candidate.

 

I'll take a closer look but I think this Boise van has only one cat post collector.

FWIW rerouting the starboard side plug wires around the cabin heat riser seems to have done the trick. A couple of trips to 4000' with half the seats occupied and no misfiring. I'll try the underhood borealis when I find a water spritzer.

Sixto
93 E150 Chateau 5.8 193K miles

 

My first thought after reading your post was the same as delgriffith, I really think you have a plugged cat.

Don't you mean the upstream sensors? By pulling those you're giving the exhaust gasses a way out around a clogged converter. If the converter is clogged the van will run much better with removed oxygen sensors. Downstream sensors after the cat wouldn't affect this at all.

 

 

I confirm one cat, one upstream sensor, no downstream sensor. I'm tempted to just replace the cat but I don't have time to do it before we head home. Shoot, then I'll be forced to pay X-times for a certified California cat. Ugh!

What makes you say left cat vs right cat?

Sixto
93 E150 Chateau 5.8 193K miles

 

Since you cured it, forget about the cats and put on new plug wires

 

I won't know that it's cured until we're home in the next couple of days.

But really, in vans so equipped, what's different about the left cat?

Sixto
93 E150 Chateau 5.8 193K miles

 

I've never heard of a plugged cat causing a "miss" or a "misfire".
The engine just won't run worth a damn due to backpressure.
They are barking up the wrong tree.

 

Possibly. But over the years I've seen a lot of folks complaining of a misfire under load in various forums that turned out to be a plugged converter. Of course not everyone understands what a misfire is either.

 

I suspect this is all too true.

 

I was one of those folks.
Catalytic converter abortion = van runs great!

 

800 uneventful miles followed by 40 miles of intermittent CEL on the ride home. No misfiring or hiccuping over the Siskiyous or Shasta. There were a couple of rises we had to slow to 45 for semi passing semi from which pedal to the floor in 3rd yielded no acceleration. Then we crested and the engine came to life. I watched the temp gauge and it didn't budge more than a half letter's width. Would a clogged exhaust cause the engine to run hot? Anyway, she's home and waiting for a bath and a code check which won't happen until the weekend.

Sixto
93 E150 Chateau 5.8 194K miles