P0303 #3 cylinder misfire solved

[KaHOnas]

It was a bad spark plug.

Duh.

But I've never had one go out like this. The center insulator cracked and it appears that the entire center electrode extended out about 2mm. I'm surprised the darn thing was firing at all.

I should have followed Occam's Razor. Anyway, the ol' Danger Ranger is running wonderfully again. 26 years and 225k miles young.

Thanks all for your help.

David
'98 XLT 4WD 5spd

 

[franklin2]

Are you having a hard time finding those type of plugs? I really liked those things on certain cars and trucks I have used them on, but I went to buy some new ones and none of the stores carry them anymore. I had to buy them off ebay.

 

[KaHOnas]

Are you having a hard time finding those type of plugs? I really liked those things on certain cars and trucks I have used them on, but I went to buy some new ones and none of the stores carry them anymore. I had to buy them off ebay.

I suspect that they may be out of production (the Bosch Platinum+4s). Rock Auto doesn't even show them as an option and they seem to have just about everything.

Edit: they're only shown available for the Ranger 2.5 on the Bosch website. +4s are still in production but not for the Ranger 4.0.

I replaced these old +4s with single electrode NGK platinums.