Hey guys, I'm getting a few OBD2 codes and I'm trying to figure out where to start. I'm getting a P1506, P0301, and a P0304. I know the P0301/4 are misfires on 1 and 4 and the truck runs like its misfiring, no power at all. Oddly the idle seems a bit high, around 1500 rpms. Any ideas where to look first? Thanks in advance for your help. 2000 Ranger 3.0.

 

Good idea to pull & post the trouble codes, as they can offer up good trouble shooting clues.

You may have more than one problem.

P1506 = Idle Air Control, overspeed error. So the computer agrees with you that idle speed is too high.

A number of things can cause idle problems, like unmeterd vacuum leaks, stuck throttle cables, dirty sticking open throttle plate, dirty stuck open, or worn PCV valve, or leaking rubber hose or fitting to it, acting out IAC, even the TPS sensor ect, ect.

SO, after warming the engine up, you might begin with trying disconnecting the IAC electrical connector & see how the engine responds. If there aren't any other problems, it should idle slower, or maybe stall, & this would suggest it's ok. Edit: If you don't have other problems, like a vacuum leak somewhere else & if the idle speed is unchanged you may have a faulty, or dirty, sticking open IAC. So maybe remove & clean it with a plastic safe spray cleaner & see how it goes. Cleaning may not last, it didn't for me, but was a good trouble shooting step.

If that proves naught, try wiggling the TPS electrical connector & see what happens. There is a TSB for it causing high idle problems because of corrosion in it's electrical connection on vehicles of our vintage. The TSB calls for splicing in/replacing the TPS electrical connector.

If the idle is still high, look to other problems I listed.

On the misfire, maybe raise the hood at night & look for arcs & sparks & or do a wet down test with a spray bottle of water of each secondary ignition component, one at a time, beginning with the two misfiring cyls & look for arcs & sparks, or a change in idle.

You didn't mention how many miles on the engine, or if it's ever had a plug & wire change, so if it has over 30K miles on the OEM plugs, their gap is likely Way over spec, at least mine were at 36K. Even after I had removed them when the vehicle was new & set the plug gap to the Low side of spec, they were .008 over Max gap spec in only 36K miles, so no way were they gonna go 100K & still be anywhere near in spec for gap!!!!

Dirty, cracked, chipped, internal or external plug insulators, loose, damaged, plug wires or connections, or cracked coilpack belong on your suspect list too. The coilpack of that era is known to crack underneath out of sight & arc to ground & cause mischief. So if everyhing else checks out, loosen & insulate it with some plastic & see if the miss gets better, or stops.

If all that checks out ok, maybe put the cam sensor on the suspect list, as it's a common problem part on the 3.0L Vulcan & can cause a misfire problem.

You really need to get the misfire problem fixed pronto, as driving it with a misfire can seriously over heat & destroy the cat converter in short order.
A bunch of thoughts for consideration to get you started, with more clues maybe we can be more specific, let us know how it goes

 

Sorry for not getting back here sooner. Thanks for the suggestions pawpaw. I will give them a go and report back.