pauls

Hey guys,

I recently brought my truck to a garage and had a new water pump put in. The truck ran perfectly fine prior but was leaking coolant from the front of the engine. After the job was done, I picked up the truck and drove it home only to find the truck shuddering and losing power. Then the check engine light came on. I kept driving home and it actually cleared up and then came back. Once home, I hooked up my reader and got a P0303 - Cyl 3 misfire. Called the shop the next day and brought it back for them to check out. Guy says it was running rough when they pulled it in the bay (no way) but its probably a coil pack. They checked the plug and said it looked fine, replaced the coil pack on passenger side and said it was fixed. Well, 2 days later, cylinder 3 misfire is back. I just did all new platinum motorcraft plugs and motorcraft wires about 8 months ago and have been driving without issue since then. Any ideas?

techrep

iTrader: (1)

wires ? what motor do you have that has plug wires...

pauls

I have a 98 XLT Supercab with the 4.6L. It has 2 coil packs with 4 terminals on each which the plug wires connect to. So late last night i swapped the plugs from cylinder three and cylinder two hoping the misfire would follow the plug to cylinder 2. Visual inspection of plugs looked good. Drove it for about 30 min nonstop and no misfire or check engine light. Im at a loss. Thing is, im trying to sell it and do not want to give it to someone and the light comes back on.

pauls

Just took it out for another 30 min or so... fine again.

twoskinsoneman

I'm sure coolant got down into the plug hole. Pull the boot. Blow it out with compressed air.

pauls

I think u were right. I pulled the plugs from 2 and 3 and swapped them to see if the misfire followed. the boot had some gunk in it and the top of the plug was filthy. I cleaned it up and re-installed it. Misfire gone for 2 plus weeks now. Thanks to all.