99 ford ranger misfire

So my truck started missing about a year ago when it was damp out or when the engine was cold. I replaced the plugs and wires and that didn’t really seem to solve the problem. Now for the last week it’s missing all the time while accelerating so tonight I replaced the coil pack and that didn’t do anything either. It’s reading a a misfire on cylinder 3 via my friends diagnostic tool. Could an o2 sensor be causing this? I replaced one on the drivers side manifold last year but I just found out it may have more than one sensor. Any ido masterminds out there with any ideas? I would like this truck to last me to at least next summer. By the way it is a 4.0 L with a 5 speed manual, and four wheel drive. Thanks for any help.

If you got spark in that cylinder…I would take a compression check on that cylinder. If that was fine since you replaced all the ignition side of it on that cylinder I be quessing an injector went bad. O2 sensor should create missfires on all cylinders on that bank….

So If I find out that the compression is bad on that cylinder the engine is probably on its way out?

Missing or knocking? Mass Airflow Censor???

It’s not knocking.

depends on whats causing it… valves, head gasket, rings even flat lobe on cam shaft. But check compression first, check another cylinder thats running right to get an idea of what compression its supposed to have. If ya got spark and compression it needs gas…to fire.

I had a 2000 Ranger, same engine, auto tran. The symptoms you describe sound exactly the same. Turned out to be a cracked head. Only one way to check that out. Good Luck.

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I had a 2000 Ranger, same engine, auto tran. The symptoms you describe sound exactly the same. Turned out to be a cracked head. Only one way to check that out. Good Luck.

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they were notorious for that issue.2.9 ltr and the 4.0 engines, if that is the case DONT even mess with used heads go NEW after market high quality rebuilts.

I have used these guys for several years >> rebuilt heads

FIRST I would start with a tune-up , ie.. plugs and wires ect and see if it went away

Neighbor had a 2000 ranger.. you guessed it, cracked head.

Well it’s going in the shop friday morning for a diagnostic run through so I guess i’ll find out then if i’m getting a newer truck.

same problem here traded it in! what they don’t know don’t hurt them haha