93 351 running rough
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93 351 running rough
It runs like one or two cylinders are misfireing. No extra noises in the engine. I have pulled plug wires one at a time, and only two made a small difference. A tune up is very difficult, and I dont think its my problem. Could it be pollution control ? an injector ? How can I trouble shoot ?
Last edited by Wangert; Nov 21, 2005 at 11:44 AM. Reason: add more info
Senior User
Joined: Feb 2005
Posts: 333
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From: Toledo, Ohio
These 5.0 and 5.8 liter engines are prone to crossfiring, so I've been told by a mechanic ( wires next to each other, firing to the wrong cylinder). They are also sensitive to old wires, cap, rotor. I've had the best luck using Motorcraft parts. How many miles on your engine? When was the last tune-up? Is your exhaust black? (possibly a sign of a bad fuel press. regulator) Good luck, John
Cargo Master
Joined: Dec 2003
Posts: 2,182
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From: Saint Augustine, FL
My first thought would be wires, cap and rotor. Kynnhoj is right about the 5.0 and 5.8 being sensitive to wires. The first time I had wires put on mine it started missfiring badly after about 1000 miles. Re-routing the wires as per Ford's documentation solved the problem. The vans in general are a little harder on the wires because the tight confines of the engine compartment reduce airflow and retain heat more. This kills the wires faster.
On these engines the most common cause of a missfire is bad plug wires so I would go there first if you haven't replaced them in a while. But it only makes sense to do the cap, rotor, wires and plugs at the same time. And stay away from platinum spark plugs. They will typically start missfiring after a few hundred miles. Standard motorcraft plugs work best. I too like the motorcraft ignition parts but "Standard" makes them for motorcraft and you can typically find standard at good autoparts stores for less than motorcraft.
Steve
'95 Clubwagon XLT
On these engines the most common cause of a missfire is bad plug wires so I would go there first if you haven't replaced them in a while. But it only makes sense to do the cap, rotor, wires and plugs at the same time. And stay away from platinum spark plugs. They will typically start missfiring after a few hundred miles. Standard motorcraft plugs work best. I too like the motorcraft ignition parts but "Standard" makes them for motorcraft and you can typically find standard at good autoparts stores for less than motorcraft.
Steve
'95 Clubwagon XLT
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