Looking at options to replace the (very old) coil packs on my Y33. Car has 208k miles. Recommend Denso 6734012 or Hitachi IGC0013?
Having a *bit* of a rough idle in gear when the engine is hot. It gets more rough the more it heat soaks.
Service manual says to test coils for resistance, "Not 0ohms" is an acceptable coil pack. Any other way?
When testing fuel injectors the spec is 10-14ohms.
Still chasing this problem P0171 lean when idling (+30% LTFT). but it pulls off good at WOT. Maybe a sneaky vac leak in the purge valve or brake booster? Just drove the car across country and it ran great.

I’d say vacuum leak. Have you changed intake manifold gasket yet? I had a rough idle for awhile that was attributed to that. When my coils went bad, it was moreso in the form of sluggish acceleration, mis/back firing. Never gave the usual misfire code or blinking check engine light though. Still seems to do it every once in awhile…though very rare. But once had a similar issue in my Maxima that didn’t take any other coil in one cylinder except hitachi. Finally fixed the misfire. All the other coils are just entry level brands.

So in my cases probably down to a wiring fault in the harness

Thanks for advice 98_Q45. I bought a smoke machine last summer and found a small vacuum leak at the intake plenum gasket. Replaced plenum gasket, PCV valves, spark plugs, cleaned TB/MAF/EGR valve. No more visible leaks from smoke testing but no change in running condition. Both banks run lean at idle. But it doesn't misfire until it warms up.
So far have had trouble checking for the hidden vac leaks. Want to pinch off hose to brake booster and purge valve independently to check source of unmetered air. Also do a cylinder drop test if I can get it warm enough to misfire.