OK - it's stating the obvious...but-

In the course of some major maintenance (new engine and ignition harnesses, rebuilt injectors, cleaned throttle body, etc.) I pulled the plugs and installed my favorites, NGK BP6ES. The replaced plugs were Bosch Super - not the recent Made in India ones, but older German made. I believe they've done about 34k mi since new five years ago. The gaps looked a little large so I checked - they varied from .037 to .042. Volvo spec is .028-.032. I know I gapped them to .030 on installation. The erosion all occurred in the center electrode.

The car was starting and running "OK", but didn't feel sharp, and fuel economy was off by maybe 10-15%. There was also a repeated hesitation under heavy or light acceleration...a kind of jerkiness rather than smooth power delivery.

With all the other work, I would damn well hope the thing runs better, but the condition of the plugs was a surprise. I now plan to shorten spark plug run time before replacement, especially with the price of gas now.
--
Bob (81-244GL B21F, 83-244DL B23F, 94-944 B230FD; plus grocery-getter Dodge minivan, MGB, and numerous old motorcycles)

I do my plugs at about 30K. I'm surprised that you saw so much Gap increase though.
I'll have to check the gap on mine when I pull them.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me

With conventional plugs I pull them an regap every 5 thousand miles or so. It makes a difference that you can feel. I've had no problem running the Bosch plugs 50 or 60 thousand miles.

Bob,

Move yet ?

I just finished my "spring" tune up, plugs, rotor, dist cap, etc. Plus, new rotors, rear calipers, e-brakes, pads. I was a bit reluctant...I've been getting 29.5 - 31 MPG on long hauls. Worried that I may wake up the fuel hog gremlins. Not so...just back from two 'day' trips' (296 and 318) and got 29.5 on the first and 31.2 on the second.

Replaced NGK with Champions (hence the worry), and as the man who fell out of the Empire State building, was heard to say at each floor, on his way down..."so far so good !!"

The kicker is:...filled up before I left, and when I retured later in the day. Gas had gone up three cents !! Filled up when I returned the second day, and gas had gone up another three cents !!!

Al



--
84, 242GLTi, 167K, 4+OD, in rehab; 89, 245 DL, 242K, M 47, daily driver; 93, 245, auto, 167K ; and other toys.

Gas argh!!
Two weekends in a row my daughter had Volleyball tournaments in New Jersey.

I would leave Long Island with 1/2 a tank just so I could Fill up in Jersey. .30 Cents cheaper there. The gas prices made up for the very very long days.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me