Oil on the electrode side of the spark plugs!

[nick325xit 5spd]

Pull the #5 plug and see if it's been fouled already. If you're immediately fouling the plugs, you're in a bad place with that engine. You might be at the hail mary top end soak stage.

[jac]

So I think it is likely the coil. I must have screwed up which coil was which when I did the coil swap initially because the issue moved cylinders this time.

I have ordered new coils. I'll let you know what happens when they get here.

[jac]

And.... It was indeed a bad coil.

Car purring nicely now and all errors cleared up.

Thanks all for your help!

[X5only]

Originally Posted by jac

And.... It was indeed a bad coil.

Car purring nicely now and all errors cleared up.

Thanks all for your help!

Now that's what I call meticulous troubleshooting - well done! And thanks for the update . My coils are still original. No troubles but I should probably change them now that the vehicle has hit 130k miles. What's your current mileage?

[Homerlovesbeer]

Good news, glad you fixed the issue.

[StephenVA]

Hopefully you up graded the plugs installed.
2.5/2.8/3.0
Iridium IX Part No. BKR6EIX, Stock No 6418, Plug gap .032”

spark plug connectors are BERU brand..if so they are per the spec noted below...1.8Kohm +/- 20%.

Coils should be .8 ohms between pin 1 and 15 (outer pins)...try a lower ohm setting on your multimeter and read them again, but these too seem to be in spec. limits.

Bad ignition coils will give you a SES light. The SES light / OBDII code will point right to the bad one.

Start with ensuring power to your ignition connector - pin 15 should have 12 volts...not fused so be careful while probing.

to test ignition coil primary resistance you can probe terminal 1 (-) and 15 (+)..and you should read approx 0.8 ohms.

to test spark plug connector resistance the Bosch should read 1Kohm +/-20%.
BERU brand should read 1.8K ohm resistance.

Ref. section 120 of Bentley's manual...pin one and 15 are the two outer pins of the three prong connector..4A is the middle pin

Replace the plug boots as they are just a short plug wire that lives in one hot area. You do have the old style square coils correct?

[jac]

Originally Posted by X5only

No troubles but I should probably change them now that the vehicle has hit 130k miles. What's your current mileage?

130K? That's brand new!

I have had mine since it first came off the lot... It now has 256k miles!

[jac]

@StephenVA: I installed NGK 3199 spark plugs and went ahead and replaced all the coils.

I verified all the other coils (besides the one on cylinder #5) were good, but I did replaced all the coils. Those were all original (old light brown square top type) or if not originals, quite old so I figured they'd go bad soon too. But I mostly just did not want to hear from my wife about how I am always working on the car.

[StephenVA]

^ good thinking!

[StephenVA]

The 3199 BKREQUP plugs are the multiprong plugs that were popular in 2000. Every manufacturer spoke about the ability of multiple ground straps (Prongs) would provide long life which they did compared to single ones. Technology moved on to fine wire plugs with center electrodes with precious metals that provide better idle stability/ignitability characteristics for lean conditions, better tip in acceleration, and better fuel economy.

Take a look at the Iridium IX - Part No. BKR6EIX, Stock No 6418, Plug gap .032”

https://ngksparkplugs.com/en/product...um-spark-plugs