Hello, So we've had this car 3 weeks ( sold our tried and true 95 850 t5 to "upgrade" for the wife) In the last few days the engine has developed a random, what ill call "klunk" or for the lack of a better explanation, feels like the motor gets "hit" I assumed a misfire of some sort. CEL never came on, but i ran the codes and got " misfire cyl#1 " Decided to start with the plugs, so i replaced them all with NGK bkr6e-11 ( i like the bkr7e for my 96 855r ) Went for a test drive, and the misfire is gone but now im feeling a slight engine vibration at mid to high rpms. Interesting side note, a few minutes in, the CEL does finally decide to come on and start flashing, then glows steady so I cleared the code. Back in the garage i pulled the plugs to check the gap, cause im a dummy and trusted the schucks counter girl who said they were pre gapped. The were at at least 40, so i took them down to 30. Test drive again, Still a slight vibration at the mid/high rpms.

So before i go any further:

Plugs.. Are the NGKs acceptable by popular opinion ?( i love them in my chipped 855R )

Whats the best gap for a bone stock motor?

If the code was tripped by a bad coil pack, would clearing it "reset" it for while? Do these coils go belly up all at once or over a period of time?

Thanks for any insight to this!

- Grae

 

I had a 1999 XC V70 have a similar problem because of a cracked coil housing in the stem of the coil pack??? do a visual on the rough cylinder... does it idle fluttery or smooth? Might try switching the coils and see if the problem transfers... could be a problematic injector too??? Additionally, I hate expensive plugs in high mileage motors... too many problem... I go with the same plugs as you... just the cheaper one and replace at 2 years. The gap is very important so call the autoparts or dealer for the gap... A lot of times the gap is on your engine sticker under the hood??? Also, sometimes the plugs ceramic breaks when installing new ones. If you have an idle flutter, disconnect a fuel injector while running, notice the change in vibration, plug it back in, and repeat for the rest of the injectors. The problem cylinder will have the least amount of change, so focus on that cylinder, coil, injector, plug, etc... (Using this process you will need to reset the OBDII codes when finished).
Good Luck! Russ