Ok, so I have had this misfire condition since i bought my truck in dec. It will only missfire when the thermastat has not yet opened. once it has opened its fine. I've replaced the crank senor, cap,rotor,plugs,wires,coil. still got the misfire. When i accelerate hard with the engine below temp the CEL will flash at me and will have a misfire condition across all cyl. except #3??? need more suggestions.

 

Cat getting clogged and /or bad o2 sensor maybe.

 

There is a good chance I'm out to lunch on this, but:

before your engine reaches operating temperature, you're in open loop and your PCM is working everything using the stored tables.. and it's dumping a lot more fuel than it needs to be to get things rolling..

I'm thinking it is running really rich, and THAT is the cause of the misfire..

do you have a programmer? are you running other than stock injectors? what plugs are you running? They wouldn't be iridium would they?

 

Thanks for the replies guys. This truck is really getting on my nerves. We can rule out the cat since it has disappeared from the truck. lol. Some more info for thought. The cap and rotor and crank sensor are from advanced auto and are BWD brand. I believe that is Borg Warner stuff?? I have tried 3 different types of sparkplugs in the truck as well. everything that I have changed does not seem to make any difference in the outcome. always has the miss till the thermostat opens up..

 

Bwd is division of Standard motor products, add in the 2000's
http://www.smpcorp.com/ABOUT%20US-History/Content.aspx.
I have used the Blue streak products for years with good success.
I would not trust any sensors other then OEM.
Had bad experience with Napa crank sensor, OEM crank sensor eliminated issue.

Dave

 

sounds like a faulty pcm

 

So after a long period of time i figured out the missfire issue with my truck. After replacing coil,plugs wires, plugs, crank sensor (2 times) ! from advanced and one from the dealer. I highly reccomend the dealer crank sensor. I found the 2 wires going to the coil had cuts in the plastic coating on them. the wires them selves were corroded and nasty looking. I replaced the wires and plug with a junk yard find. soldered and heat shrank the connection. that was about 5 months ago. The truck hasnt missed or shut off since. Just thought i would throw that out there for everyone.

 

Well, sufficient testing time at any rate.

Thanks for the solution.