When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
One detail caught my eye. The B2S1 reading was slightly higher (richer, .65 vs .44) at the beginning of the clip, before the O2s begin modulating. More of a head scratcher, but maybe a clue. Was the rough idle during the whole clip? Seemed to smooth out with higher rpms in the middle.
Here's a thought: wide spark plug gaps cause added stress to ignition components. Maybe try the "run engine in dark" trick to see if any sparks are leaking out.
Here's a thought: wide spark plug gaps cause added stress to ignition components. Maybe try the "run engine in dark" trick to see if any sparks are leaking out.
Just went out and did this (pitch black out tonight) and I can *barely* see light around each spark plug. And I mean truly a whisper.
Also got a P0304 in that short time.
EDIT: Upon further research looks like that faint blue glow I’m seeing at the base of all the plugs could be a corona discharge. Harmless if so. Not sure if new wires might help, but because these are generics that came with a pack relocation kit years ago, ordered the relocation kit from @Extinct so I can use standard length wires and replace them.
Last edited by Brandon318; Oct 26, 2025 at 09:32 AM.
Good test. Corona means "crown", something the King wears, good British institution. Maybe next monitor fuel trims to compare: cold idle vs warm idle vs highway driving. Vacuum leaks show up as more positive trims at idle compared to highway (due to compensation of A/F ratio, more air leaks in at idle because the vacuum is greater vs throttle open). Mostly impacts short term trims. Maybe smoke test? Hard for me to see a small vacuum leak causing misfires, though. Are the MAF readings normal?
Good test. Corona means "crown", something the King wears, good British institution. Maybe next monitor fuel trims to compare: cold idle vs warm idle vs highway driving. Vacuum leaks show up as more positive trims at idle compared to highway (due to compensation of A/F ratio, more air leaks in at idle because the vacuum is greater vs throttle open). Mostly impacts short term trims. Maybe smoke test? Hard for me to see a small vacuum leak causing misfires, though. Are the MAF readings normal?
I’ve never monitored fuel trims before but has been on the list of things to learn for a while now. Is this something the Nanocom can do? I have that and a Bluetooth OBD reader. I’ll start researching this and report back. Appreciate the help!
It's hard to tell much looking at the 02 voltages on an ultragauge, you really need a device that will chart the analog output. The free torque does it along with some others. Once it is charted you can tell more about the fueling.
Problem solved. Wasn't a leaking injector, still glad I took them all out though to give them a good clean.
Culprit was discovered after installing the spark plug wire relocation kit from Extinct, which replaced a different style relocation kit. The way the #4 wire was routed for that system caused it to rub against the manifold bolts, eventually wearing away the shielding.
