98 S70 - check engine light/ spark plugs

martz010185 · Post by **martz010185** » 08 Jun 2009, 16:03

My 98 S70 non-turbo (194,000 miles) has been setting off the check engine light lately.

A few weeks ago I wrote on the forum about a stalling problem. I found the source of that problem: the fuel pump was going out. But through all that trouble, I never had a CEL.

The CEL came on a day after I did a tune-up (spark plugs, wires, distributor cap/rotor, filters). When I had my car at the shop for the fuel pump, my mechanic told me that the codes were for a cylinder 2 misfire, and that the plugs I installed weren't right for my car. They're the Bosch copper plugs you can get from FCP Groton. So I took those out, bought some Volvo OEM plugs, disconnected the battery which reset the CEL, and it still came back on after that. Oddly enough, for the past week, it's gone off for a while, but then has come back on again three times. Does anyone have any ideas about this?

Thank you!

Post by **FlyingVolvo** » 08 Jun 2009, 16:19

Were the plugs gapped correctly? They should be at 0.028 inches with the error to the low side (0.026 is about the minimum). While some people swear only by OEM plugs, those Bosch Coppers (gapped @ 0.028) are generally just fine.

Also, what ignition wires did you use? Anything but OEM will give you problems.

Post by **misha** » 08 Jun 2009, 17:02

martz010185 wrote:.....So I took those out, bought some Volvo OEM plugs, disconnected the battery which reset the CEL, and it still came back on after that. Oddly enough, for the past week, it's gone off for a while, but then has come back on again three times. Does anyone have any ideas about this?

For reseting check engine light in your car you need diagnostic tool.You can't just disconnect battery and reset the codes.It is true that after disconnecting battery check engine light will go off,but that's just for a while untill ecu completes drive cycles and turn on light again(if the codes aren't cleared).
The codes remain stored in ecu untill they are cleared with diagnostic tool.
There are some situations when check engine light will go away by itself if all is ok(when malfunction is solved)but codes are still there untill you reset them.

martz010185 · Post by **martz010185** » 10 Jun 2009, 08:32

The OEM spark plugs I installed are gapless, so gapping isn't an issue with this. I haven't had the codes reset since installing the new plugs, so maybe I'll have them reset and see if they come back on after that. Thank you!