Still on 4 cylinders, some background.

[AUDIJIM at aol.com]

Since many of you are saying the same things, I'll let you know what I've 
done so far.

New #4 coil and boot.
5 new spark plugs.
2 new POS.
I have swapped #4 fuel injector with #5, no help.
I replaced 5 fuel injector inserts.
I replaced all of the fuel injector O-rings.
I checked fuel injector signal at connector, good and is the same as the 
other 4 cylinders.
I checked compression on cold engine, #4 was the best compression of the 5 
cylinders.
I physically traced the wiring from the ignition and fuel injector to the 
ECU, every thing checked out good.
I swapped a known good ECU with no help.
I removed the fuel injector rail and inserted the injectors and tested for 
fuel quantity and spay pattern, all injectors flowed the same w/ good pattern.
I removed the coil packs and boots, inserted spark plugs and grounded to 
engine, all 5 plugs sparked consistently to each other.
Spark plug condition (color and/or fuel saturation) is consistent between the 
5 cylinders.
No codes ever, unless I pull a connector from any of the fuel injectors.

Before I pull the engine, I'm going to try one last thing that two people 
mentioned/suggested, lifters. An oil change with a different viscosity may have 
influenced a bad lifter to get worse, or possibly effected the piston rings on 
#4 cylinder. I'm leaning towards the lifters right now. I come from the world 
of 10 valve turbo, and I can always hear a bad lifter on a 10v. Why can I not 
hear any lifter noise on a 20v? With this being an unknown, I will replace the 
lifters, valve cover gasket and do the whole timing belt water pump routine. 
After that, I have two more options. Replace the engine, and/or replace the 
engine and engine wiring harness. This might also account for why the engine 
feels like it smoothes out over 3000 RPM. Sometimes when it is warm and running 
smooth, if I blip the throttle, it will run rough again and clear up right 
away, but that was before the oil change. Now it runs rough a lot longer than it 
used to.

Jim
///S4cyinder