OK I am going to close this one out
Maybe a bit premature, but I hope not. Time will tell.
Steve, maybe this thread should be in a STICKY with title "24V misfire troubleshooting -- GENERAL" -- can you do this?
If you have rough running at idle, its 99% sure its not a AFM issue -- AFM is out of the picture at idle. Could be a wonky Idle Air Controller tho. If Idle is OK but at speed you have misfire its prbably good to go thru this guide to rule out any of this stuff
Lessons Learned
1. First thing is check injectors- -- put long handled screwdriver onto each injector and other end to your ear, You should easily hear CLICK CLICK CLICK on working injectors. All 6 have to be clicking!. Then , check for leaking air coming in where it shouldn't-- use brake cleaner and spray all around a warm (not hot) engine, the intake runners top and bottom, the air hose, throttle body, idle air controller, vapor separator, etc -- if you hear the engine beat change when you spray this volatile around those areas-- you have a tramp air leak that needs to get fixed.
2. If you know injectors are good, and one cylinder is missing,LISTEN for SNAP SNAP of coil arcing (bad).Bad coil usually gives a SNAP SNAP when it arcs, SNAP should be right on top of the misfire Pull front coils and plugs, check for oil in the plug well, and verify plug gap 0.025". Put back in and start car in the dark- watch for flashes around the coil -- if you find one, replace that coil. Once fronts are known good, if still SNAPPING, swap them into the rears and check verify rear plug gaps). A coil can also be bad without any SNAPPING-- its just fried! I verify coil resistance across 2 outside coil lugs as <1 ohm or so, inner one OPEN to both of the outside ones!!(its the secondary coil) ; or, you can pull a plug, ground the end of it, , pull the fuel pump relay, and have someone crank the car with the plug exposed -- you should see the spark plug sparking!
3. No snaps and still missing? VERIFY TIMING IS CORRECT (search the BB on 24 v timing)
3 and 1/2 = Timing good ? - Now swap the ignition modules connectors to see if the bad cylinder moves positions -- rear most module is for rear bank, front module for front bank. If the missing cylinder moves-- get a replacement ignition module (Located on the side / under the air box right above the ABS pump)
4. Check your fuel pressure and fuel flow. Easy to do -- for pressure, Tee in a gauge on the pass side fuel rail and start the engine -- we want about 42-46 psi. Turn engine off, and see if fuel pressure holds. If it does, proceed to step 5. If not, and it bleeds of quickly (ie < 2 minutes to below 35) then TANK DIVE to replace in-tank fuel lines that are split/leaking.
5. Jumper the secondary of the fuel pump relay to make the fuel pump run. Have it pump into a container -- if you get a full beer bottle in about 10-15 seconds you are in good shape. If not, find the blockage and fix it.
6. Still running rough? Check all 4 ground -- 2 each on intake plenum passenger side, one from throttle body to rear valve cover, and one from harness to valve cover right underneath the big round connector-- make sure that 13mm cap nut has a bunch of washers under it and the cable ground!
7. Remove rear plenum and then start checking continuity from each spark coil connector back to the big round connector. See if there is an open. Also, check each for isolation from ground and each other wire. Refer to the service manual electrical diagrams for wire colors and connectors. Then check continuity from the big round connector back to the ignition modules, check isolation too from ground and each other wire.
7, Still running rough? Time to remove the upper wiring harness from the car and examine it closely, looking for insulation breaks, etc. My break was right where the harness rubs on the water line clamp area/cam angle sensor connector mounting bracket just aft of the big round connector. Could not see it from the top, had to remove the upper harness (carries signals from big round connector to coils and injectors) and turn upside down to find the insulation breach.
8. Still running rough? Post on the 164 forum and we'll give it a good think and get back to you!