Need help reading these numbers / rough idle

[stutaeng]

Yes MPFI upgrade. I couldn’t remember what it was called. After It ran phenomenal. I had no idea it would help so much. Usually runs awesome. I put new plugs in yesterday. I just checked the plug. It’s at .06 which is what I gapped it at yesterday. I just checked the plug and it has spark. I don’t have any help so I set my phone up on record and turned over the ignition and went back and watched the video. It’s got two arc’s on it. I think the one that shouldn’t be there just grounded out through my gloves. I will go and rent a fuel pressure gauge tomorrow and return it when done.
so this is all on passenger side which is bank two. When I removed the plugs on bank two yesterday they were all worse off than one bank one.

I think there's your hint there. Bank 2 is running very rich at idle and you seem to indicate the plugs on that bank are fouled, right? With fuel? Sometimes dumping too much fuel on a given cylinder can cause misfire. I suppose too much fuel overwhelms the spark and air ratio? I don't know.

BTW, a flashing CEL light usually indicates indicates a misfire (misfire bad enough such that your catalytic converter can be damaged).

Coinsidently, at 3,000 RPM (when you actually NEED more fuel), the fuel trims seem to improve. That's what I'm hypothesizing; you'll need to prove that somehow....

How long ago were the injectors replaced? Maybe an o ring is leaking internally?

 

[Schurkey]

On a vortec you set the timing by holding the rpm steady at 1200 and twisting the distributor until the CMP pid reads 0 degrees +/- 1.

On a Vortec, the timing is NOT ADJUSTABLE. You can dick with the distributor all day long, and twice on weekends, YOU WILL NOT CHANGE THE TIMING unless you turn the distributor so far that the spark jumps to the wrong plug wire (+ or - 90 degrees.)

Turning the distributor changes the cam sensor/crank sensor synch; and aligns the rotor tip to the proper distributor cap terminal.

Unplug cylinder 2 spark plug wire while the engine is running and see if there is any change.

Doing that will drive the ignition voltage sky-high, making life very difficult for all of the insulation--cap, rotor, plug wires, ignition coil windings, etc.

It would be enormously better to GROUND the spark rather than create an open in the circuit.

Have you inspected for fowled spark plugs?

Fowl? Like chicken, turkey, ducks, etc?

 

[honkon]

OP can you monitor the upstream o2 sensors at 3000rpm? That spark plug looks wet, with gas? Did you count how many plugs were wet on bank 2?
At this point i would think you have a leak on that bank of the fuel system. Injector plumbing/control failure possibly, not personally familiar with the mpfi system.
@Schurkey The semantics aren’t helping him
"Set the timing" is incorrect terminology for a vortec but a misadjusted distributor cap can cause crossfiring and engine stalling, DTC.
Have you all the answers then explain why half of his engine is running rich at idle but purportedly stoichiometric at 3000rpm.

 

[Schurkey]

At this point i would think you have a leak on that bank of the fuel system. Injector plumbing/control failure possibly, not personally familiar with the mpfi system.

Reasonable possibility.

Not the first thing I'd go after, but that might be where it ends up.

@Schurkey The semantics aren’t helping him
"Set the timing" is incorrect terminology for a vortec but a misadjusted distributor cap can cause crossfiring and engine stalling, DTC.
Have you all the answers then explain why half of his engine is running rich at idle but purportedly stoichiometric at 3000rpm.

Certainly, the WRONG semantics aren't helping.

I've said very plainly that twisting the distributor body can get the crank sensor/cam sensor signals synchronized. The computer thinks this is important. It also makes the spark path in the distributor from rotor tip to cap terminal as optimum as it's going to get.

None of that affects the timing; and it's not a "misadjusted distributor cap", either. The issue is with the distributor BODY, and the cam sensor that's bolted to it. The cap is just along for the ride.




How do we know that "half of his engine is running rich at idle"? The computer may be reducing the fuel trim, but that doesn't mean it's not running stoich. The first code he ever mentioned was P0174--Bank 2 too lean. The spark-plug photos he's posted show some really-terrible looking firing tips. So misfire leading to false lean-code along with suddenly running like crap, seems entirely reasonable.

Things I'd like to see from the original poster:
In-focus, nicely-cropped photo of the new spark plug firing ends, laid-out IN ORDER.
Cranking compression test results of all eight.
Some sense of O2 cross-counts for Bank 1 Sensor 1, and Bank 2 Sensor 1, at idle and at 3K rpm
The distributor turned to actually synch the cam and crank sensor signals within factory spec at ~1100 rpm (+ or - 2 degrees.)
All codes cleared
CURRENT fuel pressure results, not from months ago.
Verification that there's no oil coming up the PCV system into the intake manifold.