Misfire blues

Hello all!

tl;dr: I'm getting misfire codes on cylinder 1 and 2 in my 2001, with 265,000 miles, that I can't figure out. What do?

This past weekend (Aug 22), I was at a job site that periodically required moving the car 4 or 5 city blocks. About halfway through, I started to get a bad shake/bad idle when I started the car. Interestingly, the bad idle would go away (in Park) if I stomped on the throttle to raise the speed to 1,400-2,200 rpm - it was still a little rough, but not as bad as it was at 900 rpm. At the end of the job, I limped the car home on the city streets; from, say, 15 to 35 mph, accelerating with the ICE was rough. If it was a level or downhill street, using the electric motor to maintain speed was just fine. I got the flashing Check Engine light if I was using the ICE; it would sometimes turn into the solid Check Engine light if I was just using the electric motor, but if I had to use the ICE, it would start flashing again.

At home, I pulled the codes with Techstream, and got P0300 and P0301. I sort of arbitrarily decided that this must be a bad coil/ignitor on cylinder 1, so I bought one and installed it. This seemed to smooth out the problem, except for once - I started the car and had really rough idle, so I shut it off, restarted, and it then was fine.

The car worked OK for most of Monday, and then the rough idle and P0301 recurred. I decided to swap #1 spark plug (about 30,000 miles on it) for one I had on hand (over 100,000 miles on it). That sort of calmed the problem, but sometimes I still had the rough idle. Then, I decided to swap the brand new ignitor/coil, that was on #1, to #2. That still resulted in rough idle, and a pending code for P0302. Techstream's live data for the engine showed "misfire count" on #1 and #2 cylinders going up, and nothing for #3 and #4.

I thought, possibly incorrectly, that I had been sold a bum coil/ignitor. I went to a different parts shop and bought another ignitor, installed it at #1, and kept the original 2001 Denso ignitors at #2-#4. I started the car a couple of times and got smooth, beautiful idle... and then I started it a third time and got rough idle.

I decided to actually start following the procedures in the shop manual. I inspected the vacuum hoses I could see on the engine. The PCV hose to the front (FRONT) of the throttle body previously had issues, but the electrical tape (yes really) I applied to it seemed to be holding. The PCV hose to the rear of the throttle body seemed to be OK, but it was lacking the Corbin-type clamp that the service manual suggests it has. (If it's really gone, it's been gone for a while, because there isn't a groove in the hose rubber where it would have gone. Contrast this to the front PCV hose, which also apparently calls for a Corbin-type clamp, which was present and creating a groove in the rubber.) The other vacuum hoses seemed to be OK.

Since it was easy, I measured the resistance of all four injectors (original 2001). They were all at 15.3 or 15.4 ohms, which is greater than the spec of 13.4-14.2 ohms at 68 F. Notably, #1 and #2 were not different than #3 and #4. However, the temperature of each injector, as measured by a non-contact infrared thermometer about 1" away from each injector connector, was about 90 F, so maybe that explains the increased resistance.

I *did* notice a bit of oil??? on the male (injector) and female (harness) side of the injectors, on #1, #2, and #4. #1 I can almost understand, because it's about 2.5" directly below the oil fill cap on the engine, so any spills when adding oil might end up there. #2 and #4 I can't explain. I shot some brake clean into the male (injector) side connectors, and then used a combination of Q-tips (cotton buds), paper towels, and compressed air to clean them out. I used a combination of paper towels and compressed air on the female (wiring harness) side connectors, and then reconnected them to the injectors.

I decided to replace all four spark plugs (installed at about 235,000 miles) with the previous set of spark plugs. I checked the gap on the old plugs as I installed them and they were all in spec, at 0.039-0.040". I also restored the original 2001 set of four Denso coil/ignitors at that time.

Result: smooth idle when starting, shutting off, and restarting. Smooth operation when test driving for about 15 miles. Shut off the car after 15 miles, started it again, and really rough idle again.

My next stop, tomorrow, is doing the voltage test at the ECM (to make sure the injectors aren't pulling down the voltage too much) and probably the crankshaft and camshaft position sensor resistances at the ECM (to make sure they are in spec). I may be able to test the crankshaft sensor at the source, too - it's next to the oil pan - but I'm not sure how easy it is to test the camshaft sensor, as it appears to be on the back of the head.

Any other ideas?

Thanks!