ranger_rick
New Member
2001 3.0 V6 2wd manual transmission 137k mi, owned for the last 11 years, virtually zero issues. Been chasing a misfire for over a thousand miles now. Code P0301, cylinder 1 misfire. A couple times I have also gotten a code for cylinder 3, but not consistently or frequently. It would buck or surge under heavy load, mid rpm range, and you could hear it and feel it at idle. First I did spark plugs and fuel filter. They didn’t look terrible but the new ones seemed to help briefly. Fuel filter made no difference. Misfire quickly got worse though. Compression tested, got 120 psi across all six cylinders. I then fixed a long crank-to-start with a new fuel pump/sender assembly and that seemed to fix some of the high load missing as well. I swapped plug wires with a good cylinder, no change. I swapped plug wire 1 and 5 on the coil (waste spark system means this would not change firing order, these two fire together every time), no change. Checked fuel injector clicking with a redneck stethoscope (long screwdriver), cylinders 1, 2, and 3 (passenger side/bank 1) all clicked consistently. Replaced bank 1 fuel injectors, hoping one was clogged, no change. Replaced the other three to match. Got a code once for “bank 1 rich,” which I’m guessing was because I ran it with fresh injectors on that side before changing the driver side bank. That code hasn’t come back since (200 mi or so). I happened to notice when pulling spark plug wire off cylinder 1, it wouldn’t arc consistently. Pulling it off cylinder 2, it arced consistently, so I changed the coil. Seemed to fix the issue! No miss at idle, and nothing immediately noticeable under load. Did a clutch job as the slave cylinder went out right before this, and on the 40 mile drive home from the shop, I noticed it missing under load again. P0301. Verified the new coil sparks consistently on cylinder 1. Still missing, mostly under load but occasionally at idle. Sometimes, under load, it’s really noticeable, sometimes just barely, sometimes not at all. Stabbing the throttle at low engine speed is the best way to get it to miss. It is certainly better than it was before changing the injectors, fuel pump, and coil. I then changed only the cylinder 1 plug wire. No change. Checked cylinder 1 plug, looked fine. I ran half a can of sea foam through the brake booster vacuum line, waited 10 minutes, drove it hard for 10 minutes. No change. No lean codes, no cat codes, nothing other than cylinder 1 misfire. If you pull the cylinder 1 spark plug wire while running, it does run a little worse too, so it’s not just a completely dead cylinder. Is there something I’ve forgotten to check? What am I missing here? Gas mileage has not suffered at all during all this either, fwiw. Pulling my hair out at this point and don’t want to throw any more money at it.
