Who has an eye for spark plugs?

[Vtec?lol]

Just yesterday my car was running superb

Today... Not so much.

I did a quick diagnosis by tampering with fuel, air, and spark.
Spark having the largest effect on the motor, I pulled the plugs to see what's up.




Two plugs seem strange. No wonder it sounds like a v6

They have this film on the two that's sort of like that film you get on your BBQ pits lid. Any idea?

I know shiny foul=rich
Carbon=lean (might have these backwards)
Crusty=oil

[jeffnhiscars]

My eye tells me they are AC Delcos

[Vtec?lol]

My eye tells me they are AC Delcos

Hot damn you got. Good eye fella!

Yeah, these were the plugs I found in the trunk so used em.

[enigmaticdream]

How many miles on the plugs?

[F34R]

How many miles on the plugs?

1+ and replace with Bosch or NKG.

[Vtec?lol]

About 10 miles lol.
Just bought some Bosch'
Lets see how it goes. I would like to know what would cause this?
Also bought a new fuel filter to Change the 20yr old one.

[AndrewBird]

How is it running? What exactly did you tamper with to "diagnose" it?

Why are there 8 plugs? Which ones were in the engine?

[travish325]

hi

Hello.

[jeffnhiscars]

Id number them then reinstall them in different places. That will tell you if its the plugs or the cylinder.

[kway]

The darker ones look either oil fouled, or just shitty because they weren't firing. Is this an m62? Maybe relocate the coils from those cylinders and see if the look of the plugs migrates with them.

I agree with the others, swap them for NGKs also.

[jlevie]

You have two cylinders that look to have reasonable AFR. The rest are running lean.

[Vtec?lol]

How is it running? What exactly did you tamper with to "diagnose" it?

Why are there 8 plugs? Which ones were in the engine?

They are from my m60 v8.
First I checked the fuel pressure and regulator. No change in the way it was running. I then unplugged the MAF, no change in the way it was running so I figured the MAF was bad. I then started unplugging coils one at a time to see if some weren't firing.
The fouled plugs were the one furthest to the radiator on the passenger side head and the opposite on the drivers side head.
Pulling those coils made NO difference in the way it ran so I knew they weren't sparking.

It ran very hesitant and backfired a lot. It idled steady but sounded exactly like a v6 when on the gas.

Id number them then reinstall them in different places. That will tell you if its the plugs or the cylinder.

Good idea.

The darker ones look either oil fouled, or just shitty because they weren't firing. Is this an m62? Maybe relocate the coils from those cylinders and see if the look of the plugs migrates with them.

I agree with the others, swap them for NGKs also.

Another good idea. I did this as well as mark the plugs so I can tell if its weak coils or bad cylinders.


It runs smooth now but hesitates still on full throttle.