Vets-Vet

Wouldn't this have to be injector voltage ??
After head gaskets I am troubleshooting a slight inconsistent (not always there) rough idle, especially when warm. I double checked my routine before lashing valves. Clear flood mode produces a steady and even cranking.
A previous injector balance test was exceptionally even. Yesterday I installed a new Wlabro pump and FPR so this plug read is absent that maintenance. O2 sensor replaced as well.
The injectors are fairly recent rehabs with most between 14 and 15 ohms, one at 17. Fuel rail has been cleaned and blown out twice. Recently switched back to OEM memcal. Temps in trafffic are up a small amount. Gap was .043. I ditched the AC delco's and have installed NGK's. What are your thoughts ??
Admittedly I have not had it out since the pump and FPR change, the new screws purchased for the FPR were way way to soft. Behind me sits the Mcmaster carr 18-8 SS M3.5-.6 x 12mm that I will install this afternoon.

UPDATE new fuel pressure regulator screws worked perfect Mcmaster Carr 18-8 Stainless Steel Pan Head Torx Screws, M3.5-0.60 X 12mm P/N 90362A162

This image is of the plugs pulled today. Please disregaurd the electrode tips of 2 4 6 8 as they touched while being removed.
.

ULTM8Z

Are you suspecting the driver side is a little richer than the passenger side?

Vets-Vet

Yes, but maybe the drivers side is the correct side. 2 4 6 8 look way to clean. However, it is obvious no matter what the read the left and right banks are consistently and markedly different. The question is how bad, that I can't answer. I have just sat down from installing new screws in the FPR and have not had time to look for what color they should be. My one brain cell thought slightly dirty was perfect but the internet is all over the place.

ULTM8Z

You're probably seeing the split-BLM phenomenon at low engine speeds.

I was getting something similar on my Miniram until I figured it what was happening and then constructed something to mitigate it (after finding out that the LT1 manifolds had idle air passages built into them).

https://www.thirdgen.org/forums/diy-...ram-split.html

Though in the link above, I ditched that air baffle thing in the front a long time ago. Turned out that running a long enough hose out to where their main air filter location was enough to quiet it down to being inaudible.

The ones on your driver side are essentially what my plugs look like now on all 8 cylinders after doing the above modification and then the 10% bigger injectors on cylinders 1-4.

For reference that correlates to me cruising around at ~14.5:1 on my passenger side WB AFR, and damn close to 128 BLM's everywhere as reported on the driver side NB, with the O2 rich/lean thresholds trimmed about 50-100 mV richer than factory AUJP (the richer trims happen at higher MAP values).

I get about 13.5:1 at moderate part-throttle (non-Power Enrich) due to the richer R/L thresholds. Probably not the best for fuel economy, but given what this car is, I'm erring on the side of performance.

ULTM8Z

Technically, no in the sense that BLM's are only applicable to the side with the NB O2 sensor. Although it's the batch fire that largely contributes to the problem. When you're able to tune on a per-cylinder basis, you can tune that issue out.

But rightly or wrongly I use that term "split BLM" as short hand for a difference in air/fuel distribution between the left and right cylinder banks (most common with short runner, large plenum intakes).

Because I put an O2 bung in the passenger side header, I was able to see BLM's on both sides by swapping the sensor back and forth.

Vets-Vet

Thanks for the help,
""It also looks like the plugs haven't had opportunity to "color", they look relatively fresh"" That is spot on, less than 200 miles and lots of idling while testing etc. Cats look old and rusted and the sound from them fits their appearance. Slight plastic smell I have not been able to find coming from right side, that concerned me. A little disappointed in pump pressure with new pump and FPR. I thought if running lean more flow would help. I have the 500 bucks for tires but it looks like downpipes and cats first.

I have a single row spectra and a high flow motorad 160 behind me and that will be my next project. That might be a test though as the HD radiator I believe may have been oversized. The car has a fairly new gates waterpump. Since I went into the engine the first time (before head gaskets) it has seemed to run warmer than usual but that may be the difference between old leaky OEM injectors and Bosch D III's . Still have to tune for the Bosch injectors but that will be a large learning curve and more stuff to buy.

Are the simple adjustable bolt style FPR caps as good as any ???

Thanks for the replies.
Donny