Owners manual does not indicate a dedicated heater circuit and my research thus far suggests they are controlled by the ASD relay. So if ignition coils work, ASD works and I eliminate that possibility. At 192k km I figure it’s gime
to replace the OEM o2 sensors anyway. Bought NTKs all 4 from Seller on Amazon, pair 190 and expecting credit of 30 per the negotiating I did. So $40 each not bad.... I guess.... Will I need the special tool to remove old ones or can vice grips work just the same?

Rented a fuel pressure tester today. The needle oscillated rapidly around 55 psi +/- 3. Turned engine off and removed key. Pressure after 10min is still 54psi. So does this mean my issue won’t be related to fuel pump, or pressure regulator, or fuel filter?

 

Fuel pressure likely isn't the problem.

I just used a pipe wrench to take out the old O2 sensors. I really didn't care if I trashed the hex on 'em.

 

Oh yeah I got a 7/8" wrench on the downstream bank 1 sensor no problem. Upstream 1 looks like I should be able to get it. Downstream 2 also looks accessible. For Upstream 2 should I remove passenger tire and attempt to remove from that entry point? It looks to me like that would be the only way.

 

I ended up buying a 7/8” oxygen sensor crowfoot socket that did the trick.

But replacing all 4 oxygen sensors has gotten me no closer to fixing the real issue.

Over the past couple weeks I’ve noticed cylinders 4 and 1 record the highest misfire count at the end of my trips. After a 30 min drive I’ll have ~45 misfires cylinder 4, ~35 misfires cylinder 1, <10 misfires in all others. So today I decided I would pull the spark plug and COP from 4 and 1 and swap them with 6 and 3, respectively. I started vehicle and checked misfire count - still showing cylinder 4 and 1 as the problem!!

The next area to investigate would be the injectors. Would you agree? Are special tools needed to remove fuel rail? To remove injectors from rail?

Am I right in thinking something’s gotta be going on with cylinders 4 and 1? What else could it be? If cylinders held compression then I can rule out a leaky head gasket, right?

 

I don't *think* so, but, I haven't worked on one either. I think you are going down the right path though.

If it turns out to actually be an injector problem, replace ALL of them.