2001 B1500 V6 Misfiring at Idle
 

Hello,
Looking for some help as I've been circling around this one for a while.

This summer I started getting misfire codes. Usually cylinder 3, sometimes cylinder 4. Sometimes a general misfire code. Initially I would change something and clear the code and it wouldn't return for weeks.. Now it comes back consistently.
As far as I can tell the misfires are only at idle. Idle is very rough and the engine doesn't drop when I disconnect the wires from cylinder 3 or 4. If the throttle is open then it does drop. Idle has gotten worse over time, sometimes stalling out now or slow to accelerate. Highway driving has been fine.

This started after I had replaced the plugs and wire-set so I initially thought it was ignition, but I've been up and down on the ignition system since then and am confident it is not. It seems like a vacuum issue as it only appears present at idle. I've gone over the hoses several times and tried spraying with carb cleaner and I haven't had any luck finding anything.

Looking for some tips of what to chase next or how.

Parts replaced recently:
Spark Plugs (correct gap)
Wire-set
Distributor Cap
Ignition Coil
Crankshaft Position sensor
Throttle Position Sensor
Valve Cover Gasket (leaky, scraped out lots of carbon)
PCV Valve
Throttle Body Injector Gasket (was cracked)
The PCM recently died and was replaced

Diagnosing:
Good Compression Test
Good Fuel Pressure
Moved plugs and wires and misfire did not move
IAC Valve seems to be working
Check valve to HVAC functioning
All Fuel Injectors are pulsing

I had this same issue for years; it drove me crazy. It ended up being the crank sensor, even though I replaced it several times, only to end up with the same misfire codes. The best option is an OEM one from the dealer, the second-best option is to try a different brand from a different auto parts store.

Thanks, I'll give that a try. Do you know of a way to look up mopar parts numbers for vehicles?

Rock Auto will generally have em in the "info" links with various parts. Either that, or any of the numerous mopar parts sites.

I usually go to a website like the one below and enter my VIN and the part numbers come up.

Genuine OEM Mopar Parts and Accessories Online - Mopar Parts Giant

Ok. I received the Mopar crankshaft position sensor and installed it. I am still missing at idle and getting codes for misfire on cylinder 4.

Does anyone have any other suggestions? Much appreciated.

What spark plugs did you install?

The OEM Champion copper plugs 436. Checked the gaps.
I had initially, foolishly, installed some Autolite Iridium plugs a couple weeks before the issue started. But the problem didn't stop when I replaced them with OEM.

replace the MAF

Does not have a MAF.
Does have a MAP. Which seems like a good next step. Is OEM important for MAP sensor?