Alright guys I'm at a loss. I keep having an odd intermittent miss in my 99 ranger 3.0 and I've replaced the usual suspects. 02 sensors, fuel injectors, fuel pump, plugs, wires, coil all of that to no evail. Sometimes the truck runs better than new. Other times it has a bad misfire. The codes seem to be consistent with 5 and 6. But when doing a compression test all the cylinders check out with an average of 150-170. Im at a loss, any advice?

 

Welcome to the forum!
Need some clarity. When it misfires is it just an occasional once and done, or does it last for seconds or even minutes? Is it while parked and idling or when going down the road?How does it start up in the morning or after sitting for a long period? Is this truck new to you or have you had it a while? What's the weather like when it happens? I know, strange question but weather is relevant in everything. Any trouble codes? List ALL that appear, the ones that don't appear are just as important so to say.

 

It will miss at any temp, ive had the truck for about 18 years. It seems to miss under any load. The truck sometimes will miss for a split second and be fine, other times it will last for a few minutes. And the only codes I've gotten are p0305, p0306, and p0174. Basically misfire on 5 and 6 and too lean bank 2. However the too lean bank 2 has gone away as of recent.

 

Try different gas.

 

Thats something I've thought about as well im almost empty so ill go get some good premium from a gas station with regular traffic using the pumps.

 

In diagnosing, you could switch the #5 wire to #1 spot, and #6 wire to #2 spot on the coil and see if the misfire follows.

 

I did that with my injectors to make sure it didn't follow, but I haven't done it with ignition. I'll give it a shot though.

 

Welp fuel didn't help and it's missing worse than ever. Any ideas?

 

Is it still missing on the same cylinders after you switched plug wires around as described above?

 

So I can't get the truck to throw a code but the o2 sensor read outs show its still trimming alot of fuel into bank 2. I suspect cylinder 6 and 5 at times. I'm really frustrated with this issues. I suspect cam sync or crank pos sensor, or possible a vacuum leak. What say yall.

 

Well it was an evap issue. I ended up shooting from the hip and replaced the DPFE sensor located on the intake plenum. This didn't fix the problem but gave gave me a new place to look. A check engine light came on saying there was a massive EVAP leak. Fast foward a few days I pulled the bed and the fuel pump assembly was loose! Cleaned up the seals and got it all aligned and tight and no misfire!