1998 Volvo S70 bad misfiring

rising · Post by **rising** » 11 May 2014, 14:04

Okay so my 98 GLT got parked at a friends house while we went on vacation for a week. When I came back it was running crazy rough and throwing misfire codes really bad at idle. It smoothed out a lot at speed. But then gives a flashing cel when you accelerate even lightly.

New Volvo OEM plugs a few months ago. New distributor cap and rotor too. It kinda seems like maybe a vacuum leak? I'll check the codes again and see if I find anything else. But I was wondering if anyone had an idea?

Thanks

Post by **jblackburn** » 12 May 2014, 07:13

Does it run smoothly with the MAF sensor unplugged?

How full is the gas tank? If under 1/2, go fill up with some 93 octane.

Check the plugs even though they're new; see if one is fouled with oil - when sitting, the valve seals on some of these motors will leak down a ton of oil into the cylinders - mine makes a nice blue cloud if it sits for a week.

Post by **abscate** » 12 May 2014, 09:19

Turbos can blow a hose of the induction pathway which will give this exact symptom. Check all the clamps etc from air cleaner over to the intake manifold - pull hard on hoses.

Post by **cn90** » 12 May 2014, 09:20

Check everywhere for vacuum leak (broken hoses etc.).

rising · Post by **rising** » 12 May 2014, 21:03

No the maf unplugging doesn't so anything either. Tried that. Its a newer maf anyway.

Need to pull some plugs and check though you are right.

I'll check the intake hoses too.

I think I may have figured something out. The ignition coil is making some very loud clicking noise, sounds like maybe internal shorts... So I'm gonna go ahead an put an msd blaster on it since they are a third of the price of OEM coils. See if that helps...

I'll let you guys know what I find. Thanks!

Edit: just went outside to verify and I see bright blue light coming from inside the ignition coil. I'm gonna guess that's it...

Dirk1966 · Post by **Dirk1966** » 12 May 2014, 22:48

You didn't mention the ignition leads.
Did you check these also?
I had a leak on one of them and only found out when I pulled the caps of the spark plugs with the engine running. I noticed the sparks coming from the side of the cap that goes on the spark plug

Post by **cn90** » 13 May 2014, 10:51

Get a used ignition coil from junk yard for $10.
Make sure it is Bosch.

rising · Post by **rising** » 14 May 2014, 06:25

Installed msd coil with no improvement but at least I know the old one was bad. Would've gone for a junkyard one but I'm on a busy schedule and the nearest junkyard is nearly an hour away. And then who knows if I didn't just pick up another junk coil?

Haven't checked the leads yet. They looked to be in good condition when I changed my plugs if I recall correctly so I didn't do them then. Probably should have. But could that cause multiple random misfires codes?
What's the best option for new leads? Volvo OEM? MSD? Cool blue racing ones from eBay? Lol

Post by **abscate** » 14 May 2014, 08:21

Bougicord are the bees knees for those in the know here on MVS...sneers from us with coil packs aside....(and 250 USD repair bills to boot)

But could that cause multiple random misfires codes?

Classic bad wire symptom

Post by **erikv11** » 14 May 2014, 08:25

New Bougicord wires will always work well in your car. Always. There may be some others that are reliable, I don't know.

If your wires are original (or Bougicord in general) then every wire will have a date code on it, that can help you gauge condition.